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Jenis graf untuk pembedahan pintasan femoro‐popliteal

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Abstract

Background

Femoro‐popliteal bypass is implemented to save limbs that might otherwise require amputation, in patients with ischaemic rest pain or tissue loss; and to improve walking distance in patients with severe life‐limiting claudication. Contemporary practice involves grafts using autologous vein, polytetrafluoroethylene (PTFE) or Dacron as a bypass conduit. This is the second update of a Cochrane review first published in 1999 and last updated in 2010.

Objectives

To assess the effects of bypass graft type in the treatment of stenosis or occlusion of the femoro‐popliteal arterial segment, for above‐ and below‐knee femoro‐popliteal bypass grafts.

Search methods

For this update, the Cochrane Vascular Information Specialist searched the Vascular Specialised Register (13 March 2017) and CENTRAL (2017, Issue 2). Trial registries were also searched.

Selection criteria

We included randomised trials comparing at least two different types of femoro‐popliteal grafts for arterial reconstruction in patients with femoro‐popliteal ischaemia. Randomised controlled trials comparing bypass grafting to angioplasty or to other interventions were not included.

Data collection and analysis

Both review authors (GKA and CPT) independently screened studies, extracted data, assessed trials for risk of bias and graded the quality of the evidence using GRADE criteria.

Main results

We included nineteen randomised controlled trials, with a total of 3123 patients (2547 above‐knee, 576 below‐knee bypass surgery). In total, nine graft types were compared (autologous vein, polytetrafluoroethylene (PTFE) with and without vein cuff, human umbilical vein (HUV), polyurethane (PUR), Dacron and heparin bonded Dacron (HBD); FUSION BIOLINE and Dacron with external support). Studies differed in which graft types they compared and follow‐up ranged from six months to 10 years.

Above‐knee bypass

For above‐knee bypass, there was moderate‐quality evidence that autologous vein grafts improve primary patency compared to prosthetic grafts by 60 months (Peto odds ratio (OR) 0.47, 95% confidence interval (CI) 0.28 to 0.80; 3 studies, 269 limbs; P = 0.005). We found low‐quality evidence to suggest that this benefit translated to improved secondary patency by 60 months (Peto OR 0.41, 95% CI 0.22 to 0.74; 2 studies, 176 limbs; P = 0.003).

We found no clear difference between Dacron and PTFE graft types for primary patency by 60 months (Peto OR 1.67, 95% CI 0.96 to 2.90; 2 studies, 247 limbs; low‐quality evidence). We found low‐quality evidence that Dacron grafts improved secondary patency over PTFE by 24 months (Peto OR 1.54, 95% CI 1.04 to 2.28; 2 studies, 528 limbs; P = 0.03), an effect which continued to 60 months in the single trial reporting this timepoint (Peto OR 2.43, 95% CI 1.31 to 4.53; 167 limbs; P = 0.005).

Externally supported prosthetic grafts had inferior primary patency at 24 months when compared to unsupported prosthetic grafts (Peto OR 2.08, 95% CI 1.29 to 3.35; 2 studies, 270 limbs; P = 0.003). Secondary patency was similarly affected in the single trial reporting this outcome (Peto OR 2.25, 95% CI 1.24 to 4.07; 236 limbs; P = 0.008). No data were available for 60 months follow‐up.

HUV showed benefits in primary patency over PTFE at 24 months (Peto OR 4.80, 95% CI 1.76 to 13.06; 82 limbs; P = 0.002). This benefit was still seen at 60 months (Peto OR 3.75, 95% CI 1.46 to 9.62; 69 limbs; P = 0.006), but this was only compared in one trial. Results were similar for secondary patency at 24 months (Peto OR 4.01, 95% CI 1.44 to 11.17; 93 limbs) and at 60 months (Peto OR 3.87, 95% CI 1.65 to 9.05; 93 limbs).

We found HBD to be superior to PTFE for primary patency at 60 months for above‐knee bypass, but these results were based on a single trial (Peto OR 0.38, 95% CI 0.20 to 0.72; 146 limbs; very low‐quality evidence). There was no difference in primary patency between HBD and HUV for above‐knee bypass in the one small study which reported this outcome.

We found only one small trial studying PUR and it showed very poor primary and secondary patency rates which were inferior to Dacron at all time points.

Below‐knee bypass

For bypass below the knee, we found no graft type to be superior to any other in terms of primary patency, though one trial showed improved secondary patency of HUV over PTFE at all time points to 24 months (Peto OR 3.40, 95% CI 1.45 to 7.97; 88 limbs; P = 0.005).

One study compared PTFE alone to PTFE with vein cuff; very low‐quality evidence indicates no effect to either primary or secondary patency at 24 months (Peto OR 1.08, 95% CI 0.58 to 2.01; 182 limbs; 2 studies; P = 0.80 and Peto OR 1.22, 95% CI 0.67 to 2.23; 181 limbs; 2 studies; P = 0.51 respectively)

Limited data were available for limb survival, and those studies reporting on this outcome showed no clear difference between graft types for this outcome. Antiplatelet and anticoagulant protocols varied extensively between trials, and in some cases within trials.

The overall quality of the evidence ranged from very low to moderate. Issues which affected the quality of the evidence included differences in the design of the trials, and differences in the types of grafts they compared. These differences meant we were often only able to combine and analyse small numbers of participants and this resulted in uncertainty over the true effects of the graft type used.

Authors' conclusions

There was moderate‐quality evidence of improved long‐term (60 months) primary patency for autologous vein grafts when compared to prosthetic materials for above‐knee bypasses. In the long term (two to five years) there was low‐quality evidence that Dacron confers a small secondary patency benefit over PTFE for above‐knee bypass. Only very low‐quality data exist on below‐knee bypasses, so we are uncertain which graft type is best. Further randomised data are needed to ascertain whether this information translates into an improvement in limb survival.

PICOs

Population
Intervention
Comparison
Outcome

The PICO model is widely used and taught in evidence-based health care as a strategy for formulating questions and search strategies and for characterizing clinical studies or meta-analyses. PICO stands for four different potential components of a clinical question: Patient, Population or Problem; Intervention; Comparison; Outcome.

See more on using PICO in the Cochrane Handbook.

Ringkasan bahasa mudah

Pilihan bahan graf pintasan untuk pintasan arteri kaki

Latar belakang

Seseorang yang mengalami sakit arteri yang parah di dalam satu atau kedua‐dua kaki boleh mengalami kesakitan sewaktu berjalan (klaudikasi intermiten), sakit ketika rehat, atau kematian tisu di kaki. Apabila arteri paha utama lama tersumbat, pilihan terbaik adalah memasukkan pintasan untuk membawa darah dari arteri dengan aliran darah yang baik ke arteri yang terjejas di bawah sumbatan. Pintasan bertujuan untuk memperbaiki berjalan, atau untuk menyelamatkan anggota yang mungkin memerlukan amputasi. Jenis‐jenis bahan yang sedia ada untuk membuat pintasan termasuklah vena sendiri (vena autologous), vena umbilikal manusia, dan bahan prostetik politetrafluoroetilena (PTFE) atau Dacron, secara tunggal atau dengan agen pencair darah heparin yang terikat pada bahagian dalam graf. Graf pintasan hingga ke bawah lutut adalah tidak begitu berkesan di paten berbaki (terbuka) dengan aliran darah yang baik seperti yang di atas lutut. Tujuan ulasan ini adalah untuk menentukan jenis bahan yang paling berkesan untuk digunakan pada graf pintasan di atas lutut dan di bawah lutut.

Ciri‐ciri kajian dan keputusan utama

Kami mengenal pasti 19 kajian rawak terkawal yang melibatkan sejumlah 3123 orang. Dari mereka ini, 2547 diberi pintasan graf atas lutut dan 576 diberi pintasan graf di bawah lutut. Bukti dalam ulasan kami adalah terkini sehingga 13 Mac 2017. Dari analisis kami, kami mendapati bahawa graf yang dibuat dari vena seseorang mempunyai kadar paten primer (aliran darah) lebih baik daripada bahan prostetik PTFE atau Dacron untuk pintasan graf di atas lutut. Sementara itu, Dacron (dan mungkin juga vena umbilikal manusia) mencapai aliran darah yang lebih baik (patensi) daripada PTFE. Kami juga mendapati bahawa Dacron dengan cincin sokongan di sekitarnya (yang direka untuk mencegah pemampatan luaran) menunjukkan patensi yang lebih teruk daripada Dacron yang tidak disokong apabila diguna dalam graf di atas lutut.

Menambah kaf vena tidak memperbaiki patensi PTFE untuk graf hingga ke bawah lutut. Kajian‐kajian yang disertakan memberi sedikit hasil tentang berapa lama anggota terselamat selepas prosedur pintasan. Tidak banyak konsistensi antara kajian‐kajian (dan kadang‐kadang di dalam kajian) berkaitan dengan orang yang mengambil ubat tambahan seperti antiplatelet atau antikoagulan, dan ini mungkin mempengaruhi keputusan‐keputusan.

Kualiti bukti

Kualiti bukti keseluruhan adalah sangat rendah hingga sederhana. Isu‐isu yang mempengaruhi kualiti bukti termasuklah perbezaan dalam reka bentuk kajian, dan perbezaan jenis graf yang dibandingkan. Perbezaan‐perbezaan ini bermakna kami hanya dapat menggabungkan dan menganalisis bilangan peserta yang kecil dan ini mengakibatkan ketidakpastian kesan sebenar jenis graf yang diguna.

Authors' conclusions

Implications for practice

We found moderate‐quality evidence that autologous vein grafts improve long‐term (60 months) primary patency over prosthetic graft materials for femoro‐popliteal bypass above the knee. There was low‐quality evidence that Dacron grafts had improved long‐term (two to five years) secondary patency compared to polytetrafluoroethylene (PTFE) above the knee. External reinforcement of Dacron grafts had inferior primary patency above the knee. Human umbilical cord (HUV) and heparin bonded Dacron (HBD) may also have superior patency to PTFE, but the results are from only one trial in each case. There was no evidence to support any one synthetic material for bypasses below the knee. Further randomised data are needed to ascertain whether this information translates into an improvement in limb survival.

Implications for research

Randomised trials of synthetic materials versus autologous vein and other prosthetic materials are ongoing (NCT00205790; NCT00147979). While data on new graft types are invaluable, further randomised data are needed on 'established' materials used for femoro‐popliteal bypasses. This especially includes the use of vein cuffs with different prosthetic materials below the knee. Randomised trials of HBD versus Dacron would also be useful, as would randomised data comparing 'alternative' autologous vein (for example profunda femoris, arm vein and 'inadequate' saphenous vein) with prosthetic materials.

Future trials need to include data on limb survival, quality of life and costs, as well as patency rates, to ascertain whether the improvements in patency found in this analysis translate into improvements in these important outcomes. It would also be helpful if infection rates could be reported in future trials, though the low event rates seen in observational studies of graft infection would suggest that studies looking at this issue might need to be very large.

While vein cuffs or pre‐cuffed grafts are widely utilised below the knee, this practice is based on case‐series data. This would be a useful topic to study in future trials, since vein is not always available and the results of randomised studies of this technique are conflicting.

The effects of antiplatelets or anticoagulants on graft patency also need to be investigated further in the context of randomised controlled trials. This would facilitate graft‐type trial medication protocols and remove a major potential source of bias from future studies.

Summary of findings

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Summary of findings for the main comparison. Autologous vein compared to other graft types for above‐knee femoro‐popliteal bypass surgery

Autologous vein compared to other graft types for above‐knee femoro‐popliteal bypass surgery

Patient or population: people with peripheral vascular disease requiring above‐knee femoro‐popliteal bypass surgery
Setting: hospital
Intervention: autologous vein
Comparison: other graft types

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of limbs
(studies)

Quality of the evidence
(GRADE)

Comments

Risk with other graft types

Risk with autologous vein

Primary patency

(24 months)

Study population

OR 0.59
(0.37 to 0.94)

422
(4 RCTs)

⊕⊕⊝⊝
LOW 1 2

92 fewer autologous vein grafts per 1000 (10 to 152 grafts per 1000) lose primary patency by 24 months compared to other grafts studied

275 per 1000

183 per 1000
(123 to 263)

Primary patency

(60 months)

Study population

OR 0.47
(0.28 to 0.80)

269
(3 RCTs)

⊕⊕⊕⊝
MODERATE 3

172 fewer autologous vein grafts per 1000 (54 to 264 grafts per 1000) lose primary patency by 60 months compared to other grafts studied

451 per 1000

279 per 1000
(187 to 397)

Secondary patency

(60 months)

Study population

OR 0.41
(0.22 to 0.74)

176
(2 RCTs)

⊕⊕⊝⊝
LOW 1 2

213 fewer autologous vein grafts per 1000 (75 to 330 grafts per 1000) lose secondary patency by 60 months compared to other grafts studied

526 per 1000

313 per 1000
(196 to 451)

Limb salvage

No studies of these graft types reported on this outcome

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; OR: Odds ratio

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Downgraded due to serious risk of bias resulting from lack of blinding and poor randomisation techniques
2 Downgraded due to imprecision because results based on small trials with few participants and events
3 Downgraded due to risk of bias resulting from lack of blinding and poor randomisation techniques. We did not downgrade further for imprecision because the effect was large and highly consistent between studies

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Summary of findings 2. PTFE compared to Dacron for above‐knee femoro‐popliteal bypass surgery

PTFE compared to Dacron for above‐knee femoro‐popliteal bypass surgery

Patient or population: people with peripheral vascular disease requiring above‐knee femoro‐popliteal bypass surgery
Setting: hospital
Intervention: PTFE
Comparison: Dacron

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of limbs
(studies)

Quality of the evidence
(GRADE)

Comments

Risk with Dacron

Risk with PTFE

Primary patency

(24 months)

Study population

OR 1.23
(0.92 to 1.65)

764
(4 RCTs)

⊕⊕⊝⊝
LOW 1 2

Our confidence in the effect is limited and this may differ substantially from the estimate of the effect

404 per 1000

454 per 1000
(384 to 528)

Primary patency

(60 months)

Study population

OR 1.67
(0.96 to 2.90)

247
(2 RCTs)

⊕⊕⊝⊝
LOW 1 2

Our confidence in the effect is limited and this may differ substantially from the estimate of the effect

606 per 1000

720 per 1000
(597 to 817)

Secondary patency

(24 months)

Study population

OR 1.54
(1.04 to 2.28)

528
(2 RCTs)

⊕⊕⊝⊝
LOW 1 2

81 more PTFE grafts per 1000 (7 to 168 per 1000) suffer from failed secondary patency by 24 months compared to Dacron

212 per 1000

293 per 1000
(219 to 380)

Limb salvage

(24 months)

Study population

OR 0.82
(0.27 to 2.48)

322
(1 RCT)

⊕⊕⊝⊝
LOW 1 2

Our confidence in the effect is limited and this may differ substantially from the estimate of the effect

44 per 1000

37 per 1000
(12 to 103)

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; OR: Odds ratio;PTFE: polytetrafluoroethylene

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Downgraded because of serious risk of bias due to lack of blinding and poor randomisation techniques
2 Downgraded due to imprecision because of the low number of participants and events

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Summary of findings 3. Externally supported graft compared to unsupported graft for above‐knee femoro‐popliteal bypass surgery

Externally supported graft compared to unsupported graft for above‐knee femoro‐popliteal bypass surgery

Patient or population: people with peripheral vascular disease requiring above‐knee femoro‐popliteal bypass surgery
Setting: hospital
Intervention: externally supported graft
Comparison: unsupported graft

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of limbs
(studies)

Quality of the evidence
(GRADE)

Comments

Risk with unsupported graft

Risk with externally supported graft

Primary patency

(24 months)

Study population

OR 2.08
(1.29 to 3.35)

270
(2 RCTs)

⊕⊕⊝⊝
LOW 1 2

180 fewer unsupported prosthetic grafts per 1000 (61 to 293 grafts per 1000) lose primary patency by 24 months compared to externally supported prosthetic grafts

376 per 1000

556 per 1000
(437 to 669)

Primary patency

(60 months)

No studies comparing supported and unsupported Dacron reported on primary patency at 60 months

Secondary patency

(24 months)

Study population

OR 2.25
(1.24 to 4.07)

236
(1 RCT)

⊕⊕⊝⊝
LOW 1 2

143 fewer unsupported Dacron grafts per 1000 (32 to 281 grafts per 1,000) lose secondary patency by 24 months compared to externally supported Dacron grafts

165 per 1000

308 per 1000
(197 to 446)

Limb salvage

No studies of these graft types reported on this outcome

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; OR: Odds ratio;

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Downgraded because of serious risk of bias due to lack of blinding and poor randomisation techniques
2 Downgraded due to imprecision because of the low number of participants and events

Open in table viewer
Summary of findings 4. PTFE compared to PTFE with vein cuff for below‐knee femoro‐popliteal bypass surgery

PTFE compared to PTFE with vein cuff for below‐knee femoro‐popliteal bypass surgery

Patient or population: people with peripheral vascular disease requiring below‐knee femoro‐popliteal bypass surgery
Setting: hospital
Intervention: PTFE
Comparison: PTFE with vein cuff

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of limbs
(studies)

Quality of the evidence
(GRADE)

Comments

Risk with PTFE with vein cuff

Risk with PTFE

Primary patency

(24 months)

Study population

OR 1.08
(0.58 to 2.01)

182
(2 RCTs)

⊕⊝⊝⊝
VERY LOW 1 2 3

Findings from two small trials were inconsistent so our confidence in the effect is limited and this may differ substantially from the estimate of the effect

626 per 1000

644 per 1000
(493 to 771)

Primary patency

(60 months)

No studies comparing PTFE with and without a vein cuff for below‐knee bypass reported on primary patency at 60 months

Secondary patency

(24 months)

Study population

OR 1.22
(0.67 to 2.23)

181
(2 RCTs)

⊕⊝⊝⊝
VERY LOW 1 2 3

Findings from two small trials were inconsistent so our confidence in the effect is limited and this may differ substantially from the estimate of the effect

557 per 1000

605 per 1000
(457 to 737)

Limb salvage

(24 months)

Study population

OR 1.34
(0.72 to 2.49)

196
(2 RCTs)

⊕⊕⊝⊝
LOW 1 3

Our confidence in the effect is limited and this may differ substantially from the estimate of the effect

266 per 1000

327 per 1000
(207 to 474)

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; OR: Odds ratio;

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Downgraded due to serious risk of bias resulting from lack of blinding and poor randomisation techniques
2 Downgraded due to significant heterogeneity in studies
3 Downgraded due to imprecision because of the low number of participants and events

Background

Description of the condition

Femoro‐popliteal bypass grafting for lower limb ischaemia is one of the most common procedures undertaken by vascular surgeons. Since its inception in the 1940s the procedure has evolved significantly in terms of technical intricacy, graft type, anticoagulant medication use and patient selection. Various graft types have been used, including: autologous vein (in situ or reversed), human umbilical vein (HUV), synthetic polymers, polytetrafluoroethylene (PTFE) and Dacron; and more recently heparin‐bonded synthetic polymers.

During femoro‐popliteal bypass grafting, the proximal anastomosis is taken from the common, superficial or profunda femoris artery and the distal anastomosis may be to the popliteal artery either above or below the knee (referred to as above‐ and below‐knee grafts).

Description of the intervention

Controversy still exists over the most appropriate type of graft to use in bypass surgery. It is generally accepted that autologous vein should be used wherever possible, but there are surgeons who believe that using vein is a more demanding and time‐consuming operation that involves a longer duration of anaesthesia in relatively frail patients. When vein is unavailable there are widespread differences in the material used. This is due, in part, to a lack of relevant randomised evidence. Early trials did not separate above‐ and below‐knee grafts, were underpowered, had inadequate randomisation and the patient populations were less relevant to modern practice. As new materials became available they were implemented as standard practice for many surgeons, but with a lack of high‐quality supporting evidence. Even fairly recent meta‐analyses have relied heavily on non‐randomised, retrospective data (Pereira 2006).

How the intervention might work

Arterial bypass grafting works by routing arterial blood around blocked or narrow sections of artery using an alternative conduit. This conduit may either be a section of the patient's own vein (reversed or with the valves cut and disrupted); or an alternative biological conduit such as human umbilical vein; or an artificial material.

Why it is important to do this review

Outcomes from infrainguinal bypass grafting continue to be poor; at a median follow‐up of five years, the landmark randomised trial comparing bypass surgery to angioplasty in severe limb ischaemia reported overall survival of less than 50% (Bradbury 2010). There are economic and patient advantages to successful bypass grafting (Luther 1997; Perler 1995). When this is considered in the context of the controversy surrounding choice of graft material and differences in surgical practice, it is vital to make decisions based on the best evidence currently available.

Objectives

To assess the effects of bypass graft type in the treatment of stenosis or occlusion of the femoro‐popliteal arterial segment, for above‐ and below‐knee femoro‐popliteal bypass grafts.

Methods

Criteria for considering studies for this review

Types of studies

We included randomised controlled trials (RCTs) comparing at least two different graft types. All graft types were eligible for inclusion.

Types of participants

We included patients with femoro‐popliteal ischaemia requiring arterial reconstruction. These were mainly patients with critical claudication, rest pain or tissue loss (Rutherford category 3 to 6 Consensus Document), but could also include some stable claudicants (Rutherford grade 1 to 2) in earlier trials. Trials in which a clear distinction was not made between patients receiving grafts to the popliteal artery and to the tibial arteries were excluded. For trials analysing above‐ and below‐knee procedures together, trialists were contacted for data and excluded if the results were inseparable.

Types of interventions

We included studies comparing two or more graft materials. Randomised controlled trials comparing bypass grafting to angioplasty or to other interventions were not included.

Types of outcome measures

Primary outcomes

  • Primary patency, defined as continuous patency of the graft without need for further intervention (including primary assisted patency if performed during the primary procedure)

Secondary outcomes

  • Secondary patency, defined as continuous patency of the graft, with or without further procedures such as angioplasty or surgical patching to prevent occlusion

  • Limb survival or limb salvage

We assessed these outcomes at three months, six months, one year, two years, three years and five years after surgery.

Search methods for identification of studies

We placed no restrictions on language.

Electronic searches

For this update, the Cochrane Vascular Information Specialist (CIS) searched the following databases for relevant trials:

  • the Cochrane Vascular Specialised Register (13 March 2017);

  • the Cochrane Central Register of Controlled Trials (CENTRAL (2017, Issue 2)) via the Cochrane Register of Studies Online.

See Appendix 1 for details of the search strategy used to search CENTRAL.

The Cochrane Vascular Specialised Register is maintained by the CIS and is constructed from weekly electronic searches of MEDLINE Ovid, EMBASE Ovid, CINAHL, AMED, and through handsearching relevant journals. The full list of the databases, journals and conference proceedings which have been searched, as well as the search strategies used are described in the Specialised Register section of the Cochrane Vascular module in the Cochrane Library (www.cochranelibrary.com).

The CIS also searched the following trial registries for details of ongoing and unpublished studies (13 March 2017); See Appendix 2 for details.

Searching other resources

We searched the reference lists of relevant articles identified through the electronic searches to identify further trials.

Data collection and analysis

Selection of studies

For this update, both review authors (GKA and CPT) independently selected trials for inclusion in the review. The section 'Criteria for considering studies for this review' details the inclusion criteria used for the selection process.

Data extraction and management

Data were independently extracted by GKA then cross checked by CPT. The following information was extracted on each trial.

  • Trial methods: method of randomisation, method of allocation.

  • Participants: country of origin, age, sex distribution, severity of disease as measured by the ankle brachial index (ABI) and the European Consensus definition of critical ischaemia (Consensus Document), presence of diabetes, inclusion and exclusion criteria.

  • Interventions: type of graft, level of anastomosis, use of aspirin or anticoagulants, smoking habit after surgery, attendance at a graft surveillance programme.

  • Outcomes: primary and secondary patency, limb survival.

Assessment of risk of bias in included studies

For this update, both review authors independently assessed the risk of bias in the included studies according to the guidelines given in the Cochrane Handbook for Systematic Reviews of Interventions, (Higgins 2011). We assessed the new studies included in the updated review and we re‐assessed the studies already included from the previous versions of the review.

We assessed the following domains as low risk of bias, unclear risk of bias, or high risk of bias:

  • sequence generation;

  • allocation concealment;

  • blinding of participants and personnel;

  • blinding of outcome assessment;

  • incomplete outcome data;

  • selective outcome reporting;

  • other bias.

These assessments are reported for each individual study in the Characteristics of included studies tables.

Measures of treatment effect

We presented the results from the dichotomous outcomes (primary or secondary patency; limb salvage) as odds ratios (ORs) with 95% confidence intervals (CIs).

Unit of analysis issues

The unit of analysis was the limb. Some participants in some trials were enrolled more than once, as each lower limb was allowed to be entered into some of the trials independently. This created a unit of analysis issue when considering survival with intact limb, but it was felt that effects on both primary patency (our primary outcome) and secondary patency would be small, so these trials were not excluded. None of the included studies allowed previous bypass in the affected limb. Survival data were only considered where it was clear that participants could not be enrolled in the same trial more than once.

Dealing with missing data

Where data were missing we attempted to determine the reasons for this. If data were missing due to participants being lost to follow up or because participants were not followed up to a certain time point prior to publication (censoring) and reasons were clearly described, we assumed the data were missing at random.

Assessment of heterogeneity

Heterogeneity was assessed visually (for methodological or clinical heterogeneity) by inspecting the forest plots and statistically by using Review Manager 5 software (Higgins 2003). We obtained P values comparing the test statistic with a Chi2 distribution. The Chi2 statistic describes the percentage of total variation across studies due to heterogeneity rather than by chance. A value of 0% indicates no observed heterogeneity and larger values show increasing heterogeneity.

Assessment of reporting biases

We planned to assess reporting bias by presenting funnel plots if more than 10 studies were included in the analysis. We also searched trial registries to look for unreported studies.

Data synthesis

We analysed and presented data into groups according to whether the distal anastomosis was above or below the knee.

We only undertook meta‐analysis when we felt there was no significant methodological heterogeneity, and statistical heterogeneity was not revealed by either calculation of I2 or performing Chi2 tests. The effect estimate was calculated using Peto ORs with 95% CIs. Peto ORs were used as it was anticipated that intervention effects would mainly be small, and that most trials would have similar numbers in experimental and control groups. We used fixed‐effect methods as there was no significant heterogeneity detected. All analyses were based on endpoint data from the individual clinical trials, which all quoted intention‐to‐treat results. The data were synthesised by comparing group results. Individual patient data from different trials were not amalgamated.

Subgroup analysis and investigation of heterogeneity

We performed subgroup analysis according to graft type.

Sensitivity analysis

We performed sensitivity analysis to consider whether excluding studies with higher risk of bias led to significant changes in the results.

Summary of findings

We created 'Summary of findings' tables using GRADEpro software (GRADEpro GDT 2015). The study population consisted of patients with femoro‐popliteal ischaemia requiring arterial reconstruction, and we created tables for the comparisons of 'Autologous vein compared to other graft types for above‐knee femoro‐popliteal bypass surgery' (summary of findings Table for the main comparison); 'PTFE compared to Dacron for above‐knee femoro‐popliteal bypass surgery' (summary of findings Table 2); 'Externally supported Dacron compared to unsupported Dacron for above‐knee femoro‐popliteal bypass surgery' (summary of findings Table 3) and 'PTFE compared to PTFE with vein cuff for below‐knee femoro‐popliteal bypass surgery' (summary of findings Table 4). The most important and clinically relevant outcomes (both desirable and undesirable) that were thought to be essential for decision‐making were the outcomes primary patency (at 24 and 60 months follow‐up), secondary patency (at 60 months follow‐up) and limb salvage (at 24 months follow‐up). Assumed control intervention risks were calculated by the mean number of events in the control groups of the selected studies for each outcome. We used the system developed by the Grades of Recommendation, Assessment, Development and Evaluation working group (GRADE working group) for grading the quality of evidence as high, moderate, low or very low, based on within‐study risk of bias, inconsistency, directness of evidence, imprecision, and publication bias (GRADE 2004; GRADEpro GDT 2015).

Results

Description of studies

Results of the search

See Figure 1.


Study flow diagram.

Study flow diagram.

Included studies

For summarised details of the included studies, see Characteristics of included studies.

We included seven additional studies in this review update (Davidovic 2010; Gloor 1996; Gupta 1991; Lumsden 2015; SCAMICOS 2010; Solakovic 2008; Vriens 2013), making a total of 19 randomised controlled trials which met the criteria for inclusion (Aalders 1992; Abbot 1997; Ballotta 2003; Davidovic 2010; Devine 2004; Eickhoff 1987; Gloor 1996; Gupta 1991; Jensen 2007; Klinkert 2003; Lumsden 2015; Post 2001; SCAMICOS 2010; Scharn 2008; Solakovic 2008; Stonebridge 1997; Tofigh 2007; van Det 2009; Vriens 2013). We had excluded three of the studies from the previous version of this review due to unclear randomisation methods (Gloor 1996; Gupta 1991; Solakovic 2008), but we were able to include them in this version due to the use of Cochrane's 'Risk of bias' tool. Follow‐up was reported to six months (Lumsden 2015), one year (Davidovic 2010; Gloor 1996), two years (Jensen 2007; Post 2001; Scharn 2008; Tofigh 2007; Vriens 2013), three years (Gupta 1991; SCAMICOS 2010), four years (Eickhoff 1987), five years (Aalders 1992; Abbot 1997; Ballotta 2003; Devine 2004; Klinkert 2003; Solakovic 2008; Stonebridge 1997) and 10 years (van Det 2009). There were a total of 3123 patients (2547 above‐knee, 576 below‐knee), with bypasses being performed on 3238 limbs (2662 above‐knee, 576 below‐knee). Nine types of graft were compared: autologous vein; polytetrafluoroethylene (PTFE) with and without vein cuff and with or without external support; human umbilical vein (HUV); Dacron and heparin bonded Dacron (HBD); FUSION BIOLINE and Dacron with external support).

Above‐knee bypass

Two trials compared autologous vein and PTFE grafts above the knee (Ballotta 2003; Klinkert 2003). In Ballotta 2003, 102 limbs (51 patients) with bilateral disabling claudication were randomised to receive reversed saphenous vein or PTFE. Klinkert 2003 also compared reversed saphenous vein with PTFE, in 151 limbs. Anticoagulation protocols and medication checks varied between these trials; see Characteristics of included studies for details.

In Tofigh 2007 autologous vein was compared with a polyester graft, while Solakovic 2008 compared autologous vein with a prosthetic graft, which was allowed to be either PTFE of Dacron. These have been considered separately for analysis from those trials where the prosthetic material was more clearly specified.

One trial compared PTFE with HUV in 93 limbs (Aalders 1992). Five trials compared PTFE with Dacron (Abbot 1997; Davidovic 2010; Jensen 2007; Post 2001; van Det 2009). We did not use Davidovic 2010 the quantitative analysis due to concerns over risk of bias in outcome data (see Characteristics of included studies). The trial with the largest number of limbs was Jensen 2007, in which 205 PTFE grafts were compared with 208 Dacron grafts. Unfortunately, anticoagulant and follow‐up protocols varied between departments in this study. In van Det 2009, 114 limbs were randomised to PTFE and 114 limbs to Dacron; the trialists used warfarin with a consistent protocol for anticoagulation, and they continued follow‐up for 10 years. One trial compared PTFE with the FUSION BIOLINE graft (Lumsden 2015), which is a two‐layer graft, the inner layer being heparin‐bonded expanded PTFE (ePTFE) which is glued to an outer knitted polyester textile. Above the knee, 88 limbs were randomised to FUSION BIOLINE graft, whilst 86 received standard ePTFE. Gupta 1991 considered PTFE with or without ringed support; 29 limbs received ringed grafts and 30 limbs received unringed grafts above the knee.

One trial looked at fluoropolymer‐coated Dacron graft with or without external support (Vriens 2013), with 134 limbs assigned to externally supported graft and 119 treated with unsupported graft.

One trial compared PTFE with PTFE and vein cuff in above‐knee bypass (Stonebridge 1997). The study included 74 limbs with PTFE and 76 with PTFE and vein cuff. The numbers of continuing smokers and of participants on antiplatelet and anticoagulant therapy were not given. Peri‐operative complications were not stated.

One study compared HBD with HUV (Scharn 2008) and one trial compared HBD with PTFE (Devine 2004). The anticoagulant protocol was not stated in the latter (Devine 2004).

One study compared polyurethane (PUR) with Dacron (Gloor 1996). Both primary and secondary patency rates were poor for the PUR grafts and the trial was stopped early due to safety concerns after only 20 limbs had been randomised.

Below‐knee bypass

There were far less data available for below‐knee bypass, with 651 procedures analysed. No studies compared autologous vein with PTFE, HUV or other graft types. One trial compared PTFE with Dacron (Post 2001), however there were low numbers of participants in each group (26 in the PTFE group, 27 in the Dacron group). Two trials (Stonebridge 1997; SCAMICOS 2010) compared PTFE with PTFE and vein cuff. One study (Lumsden 2015) compared standard ePTFE with the FUSION BIOLINE graft, though numbers of below‐knee popliteal procedures were low in each group (14 in the FUSION BIOLINE group, 14 in the PTFE group). Gupta 1991 included 63 below‐knee bypasses, and compared PTFE with or without ringed support in 29 and 34 limbs respectively.

One study (Eickhoff 1987) compared PTFE with HUV. This trial also separately analysed patency rates in claudicants and those with good distal runoff, and found those patients to have a patency advantage. The study authors did not state the anticoagulants used. Devine 2004 gave separate below‐knee data.

There were no statistically significant differences in the major cofounders of sex, age, smoking, dyslipidaemia (abnormal concentrations of lipids or lipoproteins in the blood), diabetes or hypertension reported between groups in any of the above‐ or below‐knee trials.

Excluded studies

For this update, we excluded six additional studies (Lindholt 2011; Linni 2015; Lundgren 2013; Midy 2016; NCT00617279; NCT00845585); we also excluded a study which had been included in previous versions of the review (Watelet 1997). We excluded three studies because above‐ and below‐the‐knee data could not be separated for analyses (Lindholt 2011, Linni 2015; Watelet 1997) . We excluded Lundgren 2013 because it included a mixture of femoro‐popliteal and femoro‐tibial bypass patients, and results for the subset of patients treated with femoro‐popliteal bypass were not presented separately. We excluded one study (Midy 2016) as it failed to recruit even 30% of the planned number of patients, and more than 25% of those recruited had no follow‐up. We excluded NCT00617279 and NCT00845585 for similar reasons; the former trial was terminated by the sponsor due to slow recruitment and no results were ever presented, whereas the latter trial was terminated before a single patient was recruited. Full reasons for trials being excluded can be found in the Characteristics of excluded studies table.

Ongoing studies

We identified two ongoing studies as being relevant to this review and these may be included in future updates (NCT00205790; NCT00147979). See Characteristics of ongoing studies.

Risk of bias in included studies

See Figure 2 and Figure 3.


Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.

Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.


Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

Overall, the risk of bias was significant, principally due to a lack of blinding. There were issues to do with attrition and it was unclear whether there might have been issues of selection bias in some studies.

Allocation

Random sequence generation

Seven studies were at low risk of bias as their sequence generation was adequate (Aalders 1992; Ballotta 2003; Devine 2004; Jensen 2007; Post 2001; Scharn 2008; van Det 2009). We judged the remaining 12 studies to have unclear risk of bias as they failed to describe the method of randomisation, or used a non‐standard technique (Abbot 1997; Davidovic 2010; Eickhoff 1987; Gloor 1996; Gupta 1991; Klinkert 2003; Lumsden 2015; SCAMICOS 2010; Scharn 2008; Solakovic 2008; Stonebridge 1997; Tofigh 2007; Vriens 2013).

Allocation concealment

Eleven studies had adequate allocation concealment (Ballotta 2003; Devine 2004; Eickhoff 1987; Jensen 2007; Klinkert 2003; Post 2001; SCAMICOS 2010; Scharn 2008; Solakovic 2008; van Det 2009; Vriens 2013). The remaining eight were at unclear risk of bias as allocation concealment was not clearly discussed (Aalders 1992; Abbot 1997; Davidovic 2010; Gloor 1996; Gupta 1991; Lumsden 2015; Stonebridge 1997; Tofigh 2007).

Blinding

Blinding for graft insertion is impossible in surgical trials of this nature. Outcome assessment may be blinded, however this was not the case in any of the included studies and we are unsure what effect this may have had on the outcomes in question. For this reason all included studies were judged to be at high risk of performance bias and at unclear risk of detection bias.

Incomplete outcome data

We judged one study (Abbot 1997) to be at high risk of attrition bias as 13 participants were lost following randomisation and results were reported without specifically stating what happened to these participants. Davidovic 2010 failed to present numbers at risk at different time points and secondary patency was presented as worse than primary patency, which is impossible. Due to these issues we judged this study to be at high risk of bias and did not include it in meta‐analysis. We assessed Gloor 1996 as having unclear risk of bias as they failed to include a CONSORT flow diagram and there was no mention of patients excluded prior to randomisation or after randomisation. All the remaining studies were at low risk of bias, since any losses were minimal or described clearly.

Selective reporting

One study (Gloor 1996) failed to present details of complications occurring within the first 30 days which did not lead to reintervention, though this was a stated secondary outcome. As this is a patient population with significant comorbidity, it is likely that there were some undisclosed complications, so we judged the study to be at unclear risk of reporting bias. There were no concerns over selective reporting in any of the other included studies.

Other potential sources of bias

Three trials had antiplatelet and anticoagulant protocols which obviously varied within the trial: Post 2001 used heparin, warfarin or antiplatelet agents (specific agent not stated); Scharn 2008 used aspirin or coumarin derivatives; and Jensen 2007 used different anticoagulation protocols in each centre. One study (Lumsden 2015) left decisions about heparin, protamine and topical haemostatics to the operating surgeon, but specified that postoperative aspirin therapy was compulsory in all participants. Five trials did not state their anticoagulation protocol (Abbot 1997; Devine 2004; Eickhoff 1987; SCAMICOS 2010; Stonebridge 1997). One study (Solakovic 2008) gave a clear protocol of anticoagulants in the perioperative period and antiplatelet agents following discharge, but gave no details of compliance checks. We considered all these studies to have unclear risk of other sources of bias.

Effects of interventions

See: Summary of findings for the main comparison Autologous vein compared to other graft types for above‐knee femoro‐popliteal bypass surgery; Summary of findings 2 PTFE compared to Dacron for above‐knee femoro‐popliteal bypass surgery; Summary of findings 3 Externally supported graft compared to unsupported graft for above‐knee femoro‐popliteal bypass surgery; Summary of findings 4 PTFE compared to PTFE with vein cuff for below‐knee femoro‐popliteal bypass surgery

Above‐knee bypass

Autologous vein compared to other graft types

Four studies compared autologous veins to other grafts prosthetic materials (Ballotta 2003; Klinkert 2003; Solakovic 2008; Tofigh 2007).

Primary patency

We were able to include four trials comparing autologous vein to prosthetic materials in a meta‐analysis (Ballotta 2003; Klinkert 2003; Solakovic 2008; Tofigh 2007). We found no clear difference between the groups in primary patency at 3, 6 or 12 months. See Analysis 1.1; Analysis 1.2; Analysis 1.3 respectively. Although individual trials failed to show clear benefit, once results of the four trials were combined a long‐term benefit for autologous vein was observed at 24 months (Peto odds ratio (OR) 0.59, 95% confidence interval (CI) 0.37 to 0.94; 422 limbs; 4 studies; P = 0.03; low‐quality evidence; Analysis 1.4). This was reflected in the continued benefit in primary patency for autologous vein over prosthetic grafts by five years (Peto OR 0.47, 95% CI 0.28 to 0.80; 269 limbs; 3 studies; P = 0.005; moderate‐quality evidence; Analysis 1.5). The comparison with polytetrafluoroethylen (PTFE) contributed the majority of weight to this result (weight 63.6%, OR 0.48, 95% CI 0.25 to 0.95).

Secondary patency

Three studies comparing autologous vein to prosthetic materials reported on this outcome and were pooled in a meta‐analysis (Klinkert 2003; Solakovic 2008; Tofigh 2007). No improvement in secondary patency was found at 3, 6, 12 or 24 months. See Analysis 1.6; Analysis 1.7; Analysis 1.8; Analysis 1.9 respectively. A benefit was seen at five years (Peto OR 0.41, 95% CI 0.22 to 0.74; 176 limbs; 2 studies; P = 0.003; low‐quality evidence; Analysis 1.10). However Ballotta 2003 and Tofigh 2007 were not included in analysis at this timepoint, reducing the power of the comparison. There was no evidence of significant statistical heterogeneity between these trials.

Limb survival or limb salvage

No data available

Polytetrafluoroethylen (PTFE) compared to other graft types

Eight studies compared PTFE to other grafts (Aalders 1992; Abbot 1997; Davidovic 2010; Jensen 2007; Lumsden 2015; Post 2001; Stonebridge 1997; van Det 2009).

Primary patency

Of the five studies comparing PTFE with Dacron (Abbot 1997; Davidovic 2010; Jensen 2007; Post 2001; van Det 2009), four were considered suitable for meta‐analysis (Abbot 1997; Jensen 2007; Post 2001; van Det 2009). We did not include Davidovic 2010 because of concerns about risk of bias (see Incomplete outcome data (attrition bias)). All four studies reported at 12 and 24 months; the remaining timepoints had data available from one or two studies. Three studies (Jensen 2007; van Det 2009; Post 2001) showed a non‐significant trend towards a greater benefit with Dacron and Abbot 1997 showed a non‐significant trend in favour of PTFE. Abbot 1997 was the weakest trial in terms of potential bias; see Figure 3 and the table Characteristics of included studies.

Once combined, we found no significant difference in primary patency between PTFE and Dacron at any time point. Removing the one trial with significant bias issues (Abbot 1997) did not change this result, except at 60 months, where data from one study (van Det 2009) suggested that Dacron grafts may potentially have a small benefit in primary patency at this time point (OR 1.87; 95% CI 1.01 to 3.43; Analysis 2.5).

One study (Aalders 1992) compared PTFE with human umbilical vein (HUV). No difference in primary patency was seen at three or six months (Analysis 2.1 and Analysis 2.2 respectively). Our analysis suggests a benefit in primary patency for HUV by 12 months (Peto OR 3.17, 95% CI 1.04 to 9.64; P = 0.04; 83 limbs; 1 study), which continued to 24 months (Peto OR 4.80, 95% CI 1.76 to 13.06; 82 limbs; 1 study; P = 0.002 (Analysis 2.4)). This benefit was still evident at five years (Peto OR 3.75, 95% CI 1.46 to 9.62; 69 limbs; 1 study; P = 0.006), Analysis 2.5), but the results are limited because of small numbers of participants.

In Stonebridge 1997, there was no significant difference between PTFE and PTFE with vein cuff used above the knee for the outcome primary patency at any time point (Analysis 2.3; Analysis 2.4).

One study (Lumsden 2015) compared a new graft material, FUSION BIOLINE, which is composed of an inner heparin bonded PTFE layer glued to an outer knitted polyester layer. This study found a significant improvement in primary patency at six months for above‐knee bypass done with FUSION BIOLINE, when compared with a standard PTFE graft (Peto OR 2.99, 95% CI 1.43 to 6.26; 174 limbs; 1 study; P = 0.004; Analysis 2.2) . Results reported at other time points were only presented for both above‐ and below‐knee grafts combined, and failed to show a significant difference at either 90 days or 12 months, though the results at six months were also significant in the combined analysis.

Secondary patency

There was no clear difference in secondary patency between PTFE and Dacron at 6 months (Peto OR 1.01, 95% CI 0.25 to 4.13; 225 limbs; 1 study) or 12 months (Peto OR 1.19, 95% CI 0.76 to 1.86; 581 limbs; 2 studies). See Analysis 2.7 and Analysis 2.8. A benefit from the use of Dacron grafts was seen at 24 months (Peto OR 1.54, 95% CI 1.04 to 2.28; 528 limbs; 2 studies; P = 0.03) and 60 months (Peto OR 2.43, 95% CI 1.31 to 4.53; 167 limbs; 1 study; P = 0.005). See Analysis 2.9 and Analysis 2.10.

In Stonebridge 1997, there was no significant difference between PTFE and PTFE with vein cuff used above the knee for the outcome secondary patency at any time point (Analysis 2.8; Analysis 2.9).

One study (Aalders 1992) compared PTFE with human umbilical vein (HUV). No clear difference in secondary patency was seen at three, six and 12 months (Analysis 2.6; Analysis 2.7 and Analysis 2.8 respectively). Our analysis suggests a benefit in secondary patency for HUV by 24 months (Peto OR 4.01, 95% CI 1.44 to 11.17; 93 limbs; 1 study; P = 0.008), which continued to 60 months (Peto OR 3.87, 95% CI 1.65 to 9.05; 93 limbs; 1 study; P = 0.002) (Analysis 2.10).

Limb survival or limb salvage

Only two studies reported detailed limb salvage rates for above‐knee femoro‐popliteal bypass (Jensen 2007; Stonebridge 1997). Jensen 2007 compared PTFE with Dacron and Stonebridge 1997 compared PTFE with PTFE and vein cuff. Neither found differences in limb salvage rates between graft types at one month or 24 months (Analysis 2.11; Analysis 2.12).

Heparin bonded Dacron (HBD) versus other grafts

Two studies compared heparin bonded Dacron grafts with other grafts (Devine 2004; Scharn 2008). Devine 2004 compared heparin bonded Dacron to PTFE and Scharn 2008 compared HBD to HUV.

Primary patency

In Devine 2004, no difference in patency was detected at 12 or 24 months, though by 60 months, HBD showed improved patency compared to PTFE (Peto OR 0.38, 95% CI 0.20 to 0.72; 146 limbs; 1 study; P = 0.003). In Scharn 2008 there was no improvement in primary patency at any time interval when HBD was compared to HUV.

The combined overall primary patency for HBD compared to HUV/PTFE was improved at 12 months (Peto OR 0.58, 95% CI 0.34 to 0.98; 294 limbs; 2 studies); 24 months (Peto OR 0.62, 95% CI 0.38 to 1.02; 282 limbs; 2 studies); and 60 months (Peto OR 0.55, 95% CI 0.33 to 0.93; 232 limbs; 2 studies). See Analysis 3.1 to Analysis 3.3.

Secondary patency

No data available

Limb survival or limb salvage

No data available

Externally‐supported Dacron or PTFE grafts compared to other grafts

One trial examined whether adding external support to Dacron might improve outcomes in above‐knee femoro‐popliteal bypass (Vriens 2013), while another considered the same question for PTFE grafts (Gupta 1991).

Primary patency

Although short‐term primary patency rates were comparable (Analysis 4.1; Analysis 4.2), by 24 months the externally supported Dacron grafts showed worse primary patency when compared to their unsupported counterparts (Peto OR 2.09, 95% CI 1.26 to 3.46; 240 limbs; 1 study; P = 0.004; Analysis 4.3).

Results from Gupta 1991 showed similar primary patency for PTFE grafts with and without ringed support at 6, 12 and 24 months (Analysis 4.1; Analysis 4.2; Analysis 4.3).

Secondary patency

Although short‐term secondary patency rates were comparable, by 24 months the externally supported Dacron grafts showed worse secondary patency when compared to their unsupported counterparts (Peto OR 2.25, 95% CI 1.24 to 4.07; 236 limbs; 1 study; P = 0.008; Analysis 4.6).

Limb survival or limb salvage

No data available

Polyurethane (PUR) graft compared to other grafts

One trial examined a new PUR graft type (Gloor 1996).

Primary patency

Primary patency was worse for the PUR grafts at all time points and the trial was stopped due to safety concerns after only 20 limbs had been randomised. See Analysis 5.1; Analysis 5.2; Analysis 5.3.

Secondary patency

Secondary patency was worse for the PUR grafts at all time points and the trial was stopped due to safety concerns after only 20 limbs had been randomised. See Analysis 5.4; Analysis 5.5; Analysis 5.6.

Limb survival or limb salvage

No data available

Below‐knee bypass

PTFE compared to other graft types

Six studies reported on primary or secondary patency, or both, but analysis was limited by different graft comparisons and reporting at different timepoints (Eickhoff 1987; Gupta 1991; Lumsden 2015; Post 2001; SCAMICOS 2010; Stonebridge 1997).

Primary patency

There was no clear difference in primary patency for PTFE compared to Dacron at 12 months (Peto OR 0.47, 95% CI 0.12 to 1.79; P = 0.27; 45 limbs; 1 study; Analysis 6.2) and 24 months (Peto OR 0.41, 95% CI 0.12 to 1.42; 40 limbs; 1 study; P = 0.16; Analysis 6.3), however the analysis only included one trial (Post 2001).

The two trials comparing PTFE with a vein cuff to PTFE alone in below‐knee femoro‐popliteal bypass were heterogeneous: Stonebridge 1997 suggested a benefit with the addition of a vein cuff, whilst SCAMICOS 2010 favoured no cuff. Pooling the data showed no difference in primary patency at six, 12 and 24 months (24 months: Peto OR 1.08, 95% CI 0.58 to 2.01; 182 limbs; 2 studies; Analysis 6.3). Allocation concealment and random sequence generation were not clearly described in Stonebridge 1997, so results may be attributable to selection bias in that trial.

One study (Gupta 1991) considered whether ringed support was of benefit in PTFE grafts below the knee. We found no difference of effect at any time point (Analysis 6.2).

A small number of patients in the FUSION BIOLINE trial had below‐knee bypass (Lumsden 2015). We found no significant difference in primary patency between FUSION BIOLINE and PTFE in this case (Analysis 6.1).

Secondary patency

One trial provided results on below‐the‐knee secondary patency for PTFE versus HUV (Eickhoff 1987).This trial showed improved patency rates for HUV grafts at all time intervals from three months to 24 months. See Analysis 6.5 to Analysis 6.8 (24 months: Peto OR 3.40; 95% CI 1.45 to 7.97, P = 0.005; 88 limbs; 1 study).

The two trials comparing PTFE with a vein cuff to PTFE alone in below‐knee femoro‐popliteal bypass were heterogeneous (SCAMICOS 2010; Stonebridge 1997). Pooling the data showed no difference in secondary patency at 12 and 24 months (24 months: (Peto OR 1.22, 95% CI 0.67 to 2.23; 181 limbs; 2 studies; Analysis 6.8). Allocation concealment and random sequence generation were not clearly described in Stonebridge 1997, so results may be attributable to selection bias in that trial.

Limb survival or limb salvage

Limited information was available on limb survival for below‐knee femoro‐popliteal bypass. Only Stonebridge 1997 and SCAMICOS 2010 reported this outcome, for PTFE versus PTFE with vein cuff. They found no clear difference at 12 months (Peto OR 1.35, 95% CI 0.72 to 2.55; 225 limbs; 2 studies) or 24 months (Peto OR 1.34, 95% CI 0.72 to 2.49; 196 limbs; 2 studies; Analysis 6.10 and Analysis 6.11).

Heparin bonded Dacron versus all other graft materials
Primary patency

Only Devine 2004 compared HBD grafts with other grafts. No clear differences in primary patency were observed between HBD and PTFE below the knee at any time interval in this study (Devine 2004; Analysis 7.1; Analysis 7.2; Analysis 7.3; Analysis 7.4;Analysis 7.5).

Secondary patency

No data available

Limb survival or limb salvage

No data available

Discussion

Summary of main results

Our major findings were that autologous vein grafts have long‐term patency benefits over prosthetic grafts in above‐knee femoro‐popliteal bypass (moderate‐quality evidence). In the long term (greater than two years), we found that Dacron may confer a slight benefit in secondary patency over polytetrafluoroethylene (PTFE) for above‐knee bypasses (low‐quality evidence). There was no significant improvement in primary and secondary patency for below‐knee PTFE bypasses when a vein cuff was included. Limited evidence was available on below‐knee procedures for all graft types. There was also limited evidence on limb survival for both above‐ and below‐knee bypass surgery.

Overall completeness and applicability of evidence

While there have been many randomised controlled trials conducted for lower limb bypass surgery, the overall quality of these was poor and meant that we had to exclude 24 trials (see Characteristics of excluded studies). Some of the main reasons we excluded trials were because they failed to randomise patients, they did not report the data for above‐ and below‐knee procedures separately, or because they had severe methodological flaws which led to significant bias within the trial.

We only found low numbers of trials for some analyses, especially for below‐knee bypass, which is partly indicative of the numbers of new graft types being introduced and partly indicative of the reduced numbers of lower‐limb bypass procedures now performed. Inclusion criteria for randomised controlled trials produce the potential problem of reducing the applicability of the results to the overall patient population. This was especially a problem in older trials, which included stable or long‐distance claudicants, who are generally not offered surgery in contemporary practice. A subcomponent of any trial including such patients will therefore not be applicable to the overall patient population, but should have a minimal effect on the overall results as these trials have smaller numbers than the more recent included trials. The included trials are largely reflective of modern surgical practice in the UK and are therefore relevant.

Data on limb salvage and survival with limb intact were generally not included for analysis in trials. In the future this should be included as it is an important outcome, both for the patient and from a health economics point of view (Luther 1997; Perler 1995), and may therefore influence practice significantly. Quality‐of‐life data would also be useful in influencing treatment strategy (Nolan 2007). This information might augment the applicability of bypass surgery in general, as evidence is still lacking when comparing infrainguinal bypass with other treatments for lower limb ischaemia (Fowkes 2008).

Human umbilical vein (HUV) has primary patency results comparable with other non‐vein graft types, and may show an improvement in primary and secondary patency compared to polytetrafluoroethylene (PTFE) below the knee. However, in one trial up to 30% of HUV grafts showed graft dilation and aneurysm formation (Aalders 1992). This, in combination with other data at the time, has led to the diminished popularity of HUV in recent years. More recent reviews did not find these factors to be a significant issue (Dardik 2002) and the patency data from this meta‐analysis infer that HUV may be a suitable alternative to synthetic materials when no autologous vein is available.

Heparin bonded Dacron is showing promising early results in randomised trials (Devine 2004). Heparin bonded PTFE is also being widely utilised in contemporary practice. While there are case series data implying that this is an effective material, we could not include data from randomised trials in this review because the results are either awaited (see table Characteristics of ongoing studies), unavailable due to the trial being terminated early (NCT00617279), or reported in a way that does not separate above‐ and below‐knee results (Lindholt 2011).

A single small trial examined the use of polyurethane (PUR) grafts (Gloor 1996). The trial was stopped early due to astonishingly poor primary and secondary patency rates in the limbs treated with the new graft material, so this material cannot be recommended.

Several specific problems could not be assessed in this analysis. Firstly, infection of synthetic bypasses has disastrous consequences for the patient (Siracuse 2013), whereas infection of venous bypasses tends not to, and is easier to treat (Reifsnyder 1992). Occlusion of synthetic bypasses appears to lead to limb loss more frequently than venous (Jackson 2000), which is why it is so important that future trials measure limb survival. A second limitation of this review is the lack of information on antiplatelet and anticoagulant protocols in the included studies; this may have produced bias in the results and their interpretation. Finally, the majority of included studies were not stratified according to graft length, inflow site quality or inflow procedures, or patency of runoff vessels. While the randomisation of participants should have achieved balance with respect to these factors, the small numbers of participants could potentially have led to imbalance between treatment arms, in turn leading to biased results.

Quality of the evidence

While there were low numbers of trials for some comparisons, these trials are mainly of reasonable methodological quality with acceptable allocation concealment techniques, though often simple sealed envelopes were used and little—if any—effort appeared to have been made to blind participants, practitioners or outcome assessors (Figure 2; Figure 3). As a result, we assessed the majority of the evidence contributing to above‐knee bypass comparisons as low quality, which rose to moderate quality for one outcome. We assessed the quality of the evidence on below‐knee bypass comparisons as very low‐quality. Further details are included in summary of findings Table for the main comparison, summary of findings Table 2, summary of findings Table 3 and summary of findings Table 4.

All trials included a Kaplan‐Meier analysis, and most supplemented this with numbers‐at‐risk and life table analyses. The numbers of participants at each stage of the trial were usually clear. However, antiplatelet protocols were generally lacking. There is clear evidence for antiplatelet therapy in cardiovascular stenting (NICE 2003), which may be applicable to lower‐limb arterial stents (Twine 2009). While the evidence is less clear for lower‐limb bypass grafts (Brown 2008; Dorffler‐Melly 2003); clear protocols should be set in future trials to avoid the potential bias caused by individual preferences by surgeons or centres for particular antiplatelets or anticoagulants. Choice of anticoagulant for lower‐limb bypass grafts requires good‐quality randomised controlled trials to determine efficacy.

Potential biases in the review process

Although we are confident that a thorough search was carried out for all relevant studies, we were unable to separate data from trials from patients of below‐ and above‐the‐knee bypasses in all cases. It has been clear for some time that below‐knee bypass grafts have significantly inferior patency rates to above‐knee grafts (Cranley 1982; McCollum 1991). Most trials since the early 1990s have therefore separated the two types of bypass for reporting results, to avoid bias. This led to the division of above‐ and below‐knee procedures in this review. Three trials which were included in previous editions of the review have been excluded in this update or previous updates (or both) as the above‐ and below‐knee data were inseparable (McCollum 1991; Moody 1992; Watelet 1997). More recent trials with combined above‐ and below‐knee procedures had other severe methodological flaws which, in combination, led us to exclude them (Robinson 1999; Robinson 2003). In addition, we excluded two more recent trials either because of combined above‐ and below‐knee numbers (Lindholt 2011), or combined below‐knee and distal bypass numbers (Lundgren 2013). See the table Characteristics of excluded studies.

Agreements and disagreements with other studies or reviews

There are several recent meta‐analyses of graft type for femoro‐popliteal bypass grafts (Albers 2005; Pereira 2006; Roll 2008; Rychlik 2014a). In Albers 2005, alternative autologous vein (defined as any autologous venous conduit other than a single section of great saphenous vein) was compared with PTFE, HUV and cryopreserved vein. Randomised controlled trials and cohort controlled trials were considered for inclusion. The authors included retrospective data and combined above‐ and below‐knee bypasses. Thirty‐two articles with 2618 patients from studies conducted between 1982 and 2004 were included. Pooled estimate analysis was performed in which the authors found no difference in primary patency between autologous vein and PTFE, but reported a significant improvement in secondary patency and foot preservation for alternative autologous veins. While not directly comparable with our analysis, these data provide more evidence for autologous vein over prosthetic grafts.

In Pereira 2006, above‐knee autologous vein, PTFE and below‐knee autologous vein were compared. Randomised controlled trials and cohort trials were considered for inclusion. Forty‐nine retrospective articles and 24 prospective articles from 1986 to 2004 were included. As well as including retrospective data, the authors included several studies which we excluded from our analysis because of inadequate randomisation. Pooled estimate analysis was performed, in which the authors found a significant improvement in primary patency for above‐knee autologous vein when compared with PTFE. Secondary patency was lower for all graft types and showed no significant difference. Therefore, Pereira 2006 also broadly agrees with the findings of this analysis that autologous vein performs better than PTFE above the knee. The authors' findings should, however, be interpreted with caution due to the nature of the data included.

One meta‐analysis (Roll 2008), compared Dacron with PTFE and found no difference between the graft types. The authors included bypasses other than femoro‐popliteal (axillo‐bifemoral, aorto‐bifemoral, etc.) but had strict inclusion criteria and therefore included good‐quality trials. Our analysis is in broad agreement with the findings of Roll 2008 in terms of primary patency, though we did find an improvement in secondary patency at 24 months and five years, the latter as a result of data from the van Det study (van Det 2009), published after Roll (Roll 2008). Therefore, the findings of our analysis are broadly in agreement with Roll 2008. For this reason, the long‐term secondary patency benefit towards Dacon is tentative, as discussed throughout the text.

One meta‐analysis (Rychlik 2014a) compared Dacron with PTFE above the knee.It had similar exclusion criteria to our review and found results from five studies which are included in our analysis, in addition to one study which we excluded from our meta‐analysis due to its methodological flaws (Davidovic 2010). They chose to include the results of Devine 2004, which compared heparin bonded Dacron with PTFE, alongside the four studies comparing standard Dacron with PTFE (Abbot 1997; Jensen 2007; Post 2001; van Det 2009). Their conclusions were similar to our results in this context: that Dacron has superior patency to PTFE at 2 and 5 years follow‐up.

A previous meta‐analysis (Twine 2012) has shown benefit for PTFE with vein cuff for below‐knee bypass. This analysis included non‐randomised studies, and based on the results seen in our analysis, the benefit shown in Twine 2012 may be because of selection bias in the non‐randomised data. It is unlikely that another RCT of cuffed bypass will be performed, and most surgeons will perform a cuffed anastomosis for synthetic bypass distal to the knee. Registry data is becoming increasingly prevalent in vascular surgery and may help to answer this question more definitively in the future.

Study flow diagram.
Figures and Tables -
Figure 1

Study flow diagram.

Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
Figures and Tables -
Figure 2

Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
Figures and Tables -
Figure 3

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 1 Primary patency at 3 months.
Figures and Tables -
Analysis 1.1

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 1 Primary patency at 3 months.

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 2 Primary patency at 6 months.
Figures and Tables -
Analysis 1.2

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 2 Primary patency at 6 months.

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 3 Primary patency at 12 months.
Figures and Tables -
Analysis 1.3

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 3 Primary patency at 12 months.

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 4 Primary patency at 24 months.
Figures and Tables -
Analysis 1.4

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 4 Primary patency at 24 months.

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 5 Primary patency at 60 months.
Figures and Tables -
Analysis 1.5

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 5 Primary patency at 60 months.

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 6 Secondary patency at 3 months.
Figures and Tables -
Analysis 1.6

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 6 Secondary patency at 3 months.

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 7 Secondary patency at 6 months.
Figures and Tables -
Analysis 1.7

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 7 Secondary patency at 6 months.

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 8 Secondary patency at 12 months.
Figures and Tables -
Analysis 1.8

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 8 Secondary patency at 12 months.

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 9 Secondary patency at 24 months.
Figures and Tables -
Analysis 1.9

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 9 Secondary patency at 24 months.

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 10 Secondary patency at 60 months.
Figures and Tables -
Analysis 1.10

Comparison 1 Above‐knee autologous vein versus all other graft materials, Outcome 10 Secondary patency at 60 months.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 1 Primary patency at 3 months.
Figures and Tables -
Analysis 2.1

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 1 Primary patency at 3 months.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 2 Primary patency at 6 months.
Figures and Tables -
Analysis 2.2

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 2 Primary patency at 6 months.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 3 Primary patency at 12 months.
Figures and Tables -
Analysis 2.3

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 3 Primary patency at 12 months.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 4 Primary patency at 24 months.
Figures and Tables -
Analysis 2.4

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 4 Primary patency at 24 months.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 5 Primary patency at 60 months.
Figures and Tables -
Analysis 2.5

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 5 Primary patency at 60 months.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 6 Secondary patency at 3 months.
Figures and Tables -
Analysis 2.6

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 6 Secondary patency at 3 months.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 7 Secondary patency at 6 months.
Figures and Tables -
Analysis 2.7

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 7 Secondary patency at 6 months.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 8 Secondary patency at 12 months.
Figures and Tables -
Analysis 2.8

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 8 Secondary patency at 12 months.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 9 Secondary patency at 24 months.
Figures and Tables -
Analysis 2.9

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 9 Secondary patency at 24 months.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 10 Secondary patency at 60 months.
Figures and Tables -
Analysis 2.10

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 10 Secondary patency at 60 months.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 11 Limb salvage at 1 month.
Figures and Tables -
Analysis 2.11

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 11 Limb salvage at 1 month.

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 12 Limb salvage at 24 months.
Figures and Tables -
Analysis 2.12

Comparison 2 Above‐knee PTFE versus all other graft materials, Outcome 12 Limb salvage at 24 months.

Comparison 3 Above‐knee heparin bonded Dacron versus all other graft materials, Outcome 1 Primary patency at 12 months.
Figures and Tables -
Analysis 3.1

Comparison 3 Above‐knee heparin bonded Dacron versus all other graft materials, Outcome 1 Primary patency at 12 months.

Comparison 3 Above‐knee heparin bonded Dacron versus all other graft materials, Outcome 2 Primary patency at 24 months.
Figures and Tables -
Analysis 3.2

Comparison 3 Above‐knee heparin bonded Dacron versus all other graft materials, Outcome 2 Primary patency at 24 months.

Comparison 3 Above‐knee heparin bonded Dacron versus all other graft materials, Outcome 3 Primary patency at 60 months.
Figures and Tables -
Analysis 3.3

Comparison 3 Above‐knee heparin bonded Dacron versus all other graft materials, Outcome 3 Primary patency at 60 months.

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 1 Primary patency at 6 months.
Figures and Tables -
Analysis 4.1

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 1 Primary patency at 6 months.

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 2 Primary patency at 12 months.
Figures and Tables -
Analysis 4.2

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 2 Primary patency at 12 months.

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 3 Primary patency at 24 months.
Figures and Tables -
Analysis 4.3

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 3 Primary patency at 24 months.

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 4 Secondary patency at 6 months.
Figures and Tables -
Analysis 4.4

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 4 Secondary patency at 6 months.

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 5 Secondary patency at 12 months.
Figures and Tables -
Analysis 4.5

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 5 Secondary patency at 12 months.

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 6 Secondary patency at 24 months.
Figures and Tables -
Analysis 4.6

Comparison 4 Above‐knee externally supported graft versus unsupported graft materials, Outcome 6 Secondary patency at 24 months.

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 1 Primary patency at 3 months.
Figures and Tables -
Analysis 5.1

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 1 Primary patency at 3 months.

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 2 Primary patency at 6 months.
Figures and Tables -
Analysis 5.2

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 2 Primary patency at 6 months.

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 3 Primary patency at 12 months.
Figures and Tables -
Analysis 5.3

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 3 Primary patency at 12 months.

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 4 Secondary patency at 3 months.
Figures and Tables -
Analysis 5.4

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 4 Secondary patency at 3 months.

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 5 Secondary patency at 6 months.
Figures and Tables -
Analysis 5.5

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 5 Secondary patency at 6 months.

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 6 Secondary patency at 12 months.
Figures and Tables -
Analysis 5.6

Comparison 5 Above‐knee polyurethane (PUR) versus all other graft materials, Outcome 6 Secondary patency at 12 months.

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 1 Primary patency at 6 months.
Figures and Tables -
Analysis 6.1

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 1 Primary patency at 6 months.

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 2 Primary patency at 12 months.
Figures and Tables -
Analysis 6.2

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 2 Primary patency at 12 months.

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 3 Primary patency at 24 months.
Figures and Tables -
Analysis 6.3

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 3 Primary patency at 24 months.

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 4 Primary patency at 36 months.
Figures and Tables -
Analysis 6.4

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 4 Primary patency at 36 months.

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 5 Secondary patency at 3 months.
Figures and Tables -
Analysis 6.5

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 5 Secondary patency at 3 months.

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 6 Secondary patency at 6 months.
Figures and Tables -
Analysis 6.6

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 6 Secondary patency at 6 months.

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 7 Secondary patency at 12 months.
Figures and Tables -
Analysis 6.7

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 7 Secondary patency at 12 months.

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 8 Secondary patency at 24 months.
Figures and Tables -
Analysis 6.8

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 8 Secondary patency at 24 months.

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 9 Secondary patency at 36 months.
Figures and Tables -
Analysis 6.9

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 9 Secondary patency at 36 months.

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 10 Limb salvage at 12 months.
Figures and Tables -
Analysis 6.10

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 10 Limb salvage at 12 months.

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 11 Limb salvage at 24 months.
Figures and Tables -
Analysis 6.11

Comparison 6 Below‐knee PTFE versus all other graft materials, Outcome 11 Limb salvage at 24 months.

Comparison 7 Below‐knee heparin bonded Dacron versus all other graft materials, Outcome 1 Primary patency at 3 months.
Figures and Tables -
Analysis 7.1

Comparison 7 Below‐knee heparin bonded Dacron versus all other graft materials, Outcome 1 Primary patency at 3 months.

Comparison 7 Below‐knee heparin bonded Dacron versus all other graft materials, Outcome 2 Primary patency at 6 months.
Figures and Tables -
Analysis 7.2

Comparison 7 Below‐knee heparin bonded Dacron versus all other graft materials, Outcome 2 Primary patency at 6 months.

Comparison 7 Below‐knee heparin bonded Dacron versus all other graft materials, Outcome 3 Primary patency at 12 months.
Figures and Tables -
Analysis 7.3

Comparison 7 Below‐knee heparin bonded Dacron versus all other graft materials, Outcome 3 Primary patency at 12 months.

Comparison 7 Below‐knee heparin bonded Dacron versus all other graft materials, Outcome 4 Primary patency at 24 months.
Figures and Tables -
Analysis 7.4

Comparison 7 Below‐knee heparin bonded Dacron versus all other graft materials, Outcome 4 Primary patency at 24 months.

Comparison 7 Below‐knee heparin bonded Dacron versus all other graft materials, Outcome 5 Primary patency at 60 months.
Figures and Tables -
Analysis 7.5

Comparison 7 Below‐knee heparin bonded Dacron versus all other graft materials, Outcome 5 Primary patency at 60 months.

Summary of findings for the main comparison. Autologous vein compared to other graft types for above‐knee femoro‐popliteal bypass surgery

Autologous vein compared to other graft types for above‐knee femoro‐popliteal bypass surgery

Patient or population: people with peripheral vascular disease requiring above‐knee femoro‐popliteal bypass surgery
Setting: hospital
Intervention: autologous vein
Comparison: other graft types

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of limbs
(studies)

Quality of the evidence
(GRADE)

Comments

Risk with other graft types

Risk with autologous vein

Primary patency

(24 months)

Study population

OR 0.59
(0.37 to 0.94)

422
(4 RCTs)

⊕⊕⊝⊝
LOW 1 2

92 fewer autologous vein grafts per 1000 (10 to 152 grafts per 1000) lose primary patency by 24 months compared to other grafts studied

275 per 1000

183 per 1000
(123 to 263)

Primary patency

(60 months)

Study population

OR 0.47
(0.28 to 0.80)

269
(3 RCTs)

⊕⊕⊕⊝
MODERATE 3

172 fewer autologous vein grafts per 1000 (54 to 264 grafts per 1000) lose primary patency by 60 months compared to other grafts studied

451 per 1000

279 per 1000
(187 to 397)

Secondary patency

(60 months)

Study population

OR 0.41
(0.22 to 0.74)

176
(2 RCTs)

⊕⊕⊝⊝
LOW 1 2

213 fewer autologous vein grafts per 1000 (75 to 330 grafts per 1000) lose secondary patency by 60 months compared to other grafts studied

526 per 1000

313 per 1000
(196 to 451)

Limb salvage

No studies of these graft types reported on this outcome

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; OR: Odds ratio

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Downgraded due to serious risk of bias resulting from lack of blinding and poor randomisation techniques
2 Downgraded due to imprecision because results based on small trials with few participants and events
3 Downgraded due to risk of bias resulting from lack of blinding and poor randomisation techniques. We did not downgrade further for imprecision because the effect was large and highly consistent between studies

Figures and Tables -
Summary of findings for the main comparison. Autologous vein compared to other graft types for above‐knee femoro‐popliteal bypass surgery
Summary of findings 2. PTFE compared to Dacron for above‐knee femoro‐popliteal bypass surgery

PTFE compared to Dacron for above‐knee femoro‐popliteal bypass surgery

Patient or population: people with peripheral vascular disease requiring above‐knee femoro‐popliteal bypass surgery
Setting: hospital
Intervention: PTFE
Comparison: Dacron

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of limbs
(studies)

Quality of the evidence
(GRADE)

Comments

Risk with Dacron

Risk with PTFE

Primary patency

(24 months)

Study population

OR 1.23
(0.92 to 1.65)

764
(4 RCTs)

⊕⊕⊝⊝
LOW 1 2

Our confidence in the effect is limited and this may differ substantially from the estimate of the effect

404 per 1000

454 per 1000
(384 to 528)

Primary patency

(60 months)

Study population

OR 1.67
(0.96 to 2.90)

247
(2 RCTs)

⊕⊕⊝⊝
LOW 1 2

Our confidence in the effect is limited and this may differ substantially from the estimate of the effect

606 per 1000

720 per 1000
(597 to 817)

Secondary patency

(24 months)

Study population

OR 1.54
(1.04 to 2.28)

528
(2 RCTs)

⊕⊕⊝⊝
LOW 1 2

81 more PTFE grafts per 1000 (7 to 168 per 1000) suffer from failed secondary patency by 24 months compared to Dacron

212 per 1000

293 per 1000
(219 to 380)

Limb salvage

(24 months)

Study population

OR 0.82
(0.27 to 2.48)

322
(1 RCT)

⊕⊕⊝⊝
LOW 1 2

Our confidence in the effect is limited and this may differ substantially from the estimate of the effect

44 per 1000

37 per 1000
(12 to 103)

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; OR: Odds ratio;PTFE: polytetrafluoroethylene

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Downgraded because of serious risk of bias due to lack of blinding and poor randomisation techniques
2 Downgraded due to imprecision because of the low number of participants and events

Figures and Tables -
Summary of findings 2. PTFE compared to Dacron for above‐knee femoro‐popliteal bypass surgery
Summary of findings 3. Externally supported graft compared to unsupported graft for above‐knee femoro‐popliteal bypass surgery

Externally supported graft compared to unsupported graft for above‐knee femoro‐popliteal bypass surgery

Patient or population: people with peripheral vascular disease requiring above‐knee femoro‐popliteal bypass surgery
Setting: hospital
Intervention: externally supported graft
Comparison: unsupported graft

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of limbs
(studies)

Quality of the evidence
(GRADE)

Comments

Risk with unsupported graft

Risk with externally supported graft

Primary patency

(24 months)

Study population

OR 2.08
(1.29 to 3.35)

270
(2 RCTs)

⊕⊕⊝⊝
LOW 1 2

180 fewer unsupported prosthetic grafts per 1000 (61 to 293 grafts per 1000) lose primary patency by 24 months compared to externally supported prosthetic grafts

376 per 1000

556 per 1000
(437 to 669)

Primary patency

(60 months)

No studies comparing supported and unsupported Dacron reported on primary patency at 60 months

Secondary patency

(24 months)

Study population

OR 2.25
(1.24 to 4.07)

236
(1 RCT)

⊕⊕⊝⊝
LOW 1 2

143 fewer unsupported Dacron grafts per 1000 (32 to 281 grafts per 1,000) lose secondary patency by 24 months compared to externally supported Dacron grafts

165 per 1000

308 per 1000
(197 to 446)

Limb salvage

No studies of these graft types reported on this outcome

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; OR: Odds ratio;

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Downgraded because of serious risk of bias due to lack of blinding and poor randomisation techniques
2 Downgraded due to imprecision because of the low number of participants and events

Figures and Tables -
Summary of findings 3. Externally supported graft compared to unsupported graft for above‐knee femoro‐popliteal bypass surgery
Summary of findings 4. PTFE compared to PTFE with vein cuff for below‐knee femoro‐popliteal bypass surgery

PTFE compared to PTFE with vein cuff for below‐knee femoro‐popliteal bypass surgery

Patient or population: people with peripheral vascular disease requiring below‐knee femoro‐popliteal bypass surgery
Setting: hospital
Intervention: PTFE
Comparison: PTFE with vein cuff

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of limbs
(studies)

Quality of the evidence
(GRADE)

Comments

Risk with PTFE with vein cuff

Risk with PTFE

Primary patency

(24 months)

Study population

OR 1.08
(0.58 to 2.01)

182
(2 RCTs)

⊕⊝⊝⊝
VERY LOW 1 2 3

Findings from two small trials were inconsistent so our confidence in the effect is limited and this may differ substantially from the estimate of the effect

626 per 1000

644 per 1000
(493 to 771)

Primary patency

(60 months)

No studies comparing PTFE with and without a vein cuff for below‐knee bypass reported on primary patency at 60 months

Secondary patency

(24 months)

Study population

OR 1.22
(0.67 to 2.23)

181
(2 RCTs)

⊕⊝⊝⊝
VERY LOW 1 2 3

Findings from two small trials were inconsistent so our confidence in the effect is limited and this may differ substantially from the estimate of the effect

557 per 1000

605 per 1000
(457 to 737)

Limb salvage

(24 months)

Study population

OR 1.34
(0.72 to 2.49)

196
(2 RCTs)

⊕⊕⊝⊝
LOW 1 3

Our confidence in the effect is limited and this may differ substantially from the estimate of the effect

266 per 1000

327 per 1000
(207 to 474)

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; OR: Odds ratio;

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Downgraded due to serious risk of bias resulting from lack of blinding and poor randomisation techniques
2 Downgraded due to significant heterogeneity in studies
3 Downgraded due to imprecision because of the low number of participants and events

Figures and Tables -
Summary of findings 4. PTFE compared to PTFE with vein cuff for below‐knee femoro‐popliteal bypass surgery
Comparison 1. Above‐knee autologous vein versus all other graft materials

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Primary patency at 3 months Show forest plot

4

466

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.20 [0.58, 2.48]

1.1 Autologous vein v PTFE

2

249

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.27 [0.41, 3.97]

1.2 Autologous vein v other graft types

2

217

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.16 [0.45, 2.96]

2 Primary patency at 6 months Show forest plot

4

452

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.01 [0.56, 1.83]

2.1 Autologous vein v PTFE

2

245

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.12 [0.45, 2.78]

2.2 Autologous vein v other graft types

2

207

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.94 [0.43, 2.05]

3 Primary patency at 12 months Show forest plot

4

440

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.73 [0.44, 1.22]

3.1 Autologous vein v PTFE

2

238

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.81 [0.37, 1.76]

3.2 Autologous vein v other graft types

2

202

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.67 [0.34, 1.33]

4 Primary patency at 24 months Show forest plot

4

422

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.59 [0.37, 0.94]

4.1 Autologous vein vs PTFE

2

232

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.67 [0.34, 1.33]

4.2 Autologous vein vs other graft types

2

190

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.52 [0.28, 0.99]

5 Primary patency at 60 months Show forest plot

3

269

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.47 [0.28, 0.80]

5.1 Autologous vein v PTFE

2

191

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.48 [0.25, 0.95]

5.2 Autologous vein vs other graft type

1

78

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.44 [0.18, 1.07]

6 Secondary patency at 3 months Show forest plot

3

364

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.05 [0.47, 2.32]

6.1 Autologous vein v PTFE

1

147

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.08 [0.30, 3.87]

6.2 Autologous vein v other graft types

2

217

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.03 [0.37, 2.83]

7 Secondary patency at 6 months Show forest plot

3

351

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.95 [0.49, 1.82]

7.1 Autologous vein v PTFE

1

143

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.98 [0.36, 2.69]

7.2 Autologous vein v other graft types

2

208

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.92 [0.39, 2.19]

8 Secondary patency at 12 months Show forest plot

3

338

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.81 [0.45, 1.45]

8.1 Autologous vein v PTFE

1

136

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.99 [0.39, 2.51]

8.2 Autologous vein v other graft types

2

202

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.71 [0.34, 1.50]

9 Secondary patency at 24 months Show forest plot

3

320

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.70 [0.41, 1.19]

9.1 Autologous vein v PTFE

1

130

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.83 [0.37, 1.87]

9.2 Autologous vein v other graft type

2

190

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.62 [0.31, 1.24]

10 Secondary patency at 60 months Show forest plot

2

176

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.41 [0.22, 0.74]

10.1 Autologous vein v PTFE

1

98

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.44 [0.20, 0.99]

10.2 Autologous vein v other graft types

1

78

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.37 [0.15, 0.90]

Figures and Tables -
Comparison 1. Above‐knee autologous vein versus all other graft materials
Comparison 2. Above‐knee PTFE versus all other graft materials

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Primary patency at 3 months Show forest plot

2

312

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.36 [0.81, 6.87]

1.1 PTFE v HUV

1

93

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.55 [0.26, 9.33]

1.2 PTFE v Dacron

1

219

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.97 [0.78, 11.25]

2 Primary patency at 6 months Show forest plot

5

824

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.11 [1.37, 3.25]

2.1 PTFE v HUV

1

90

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.56 [0.69, 9.47]

2.2 PTFE v Dacron

2

421

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.57 [0.79, 3.11]

2.3 PTFE v PTFE with vein cuff

1

139

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.80 [0.57, 5.60]

2.4 PTFE v FUSION BIOLINE

1

174

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.99 [1.43, 6.26]

3 Primary patency at 12 months Show forest plot

6

1088

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.23 [0.93, 1.64]

3.1 PTFE v HUV

1

83

Peto Odds Ratio (Peto, Fixed, 95% CI)

3.17 [1.04, 9.64]

3.2 PTFE v Dacron

4

875

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.24 [0.91, 1.70]

3.3 PTFE v PTFE with vein cuff

1

130

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.64 [0.26, 1.56]

4 Primary patency at 24 months Show forest plot

6

945

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.31 [1.00, 1.71]

4.1 PTFE V HUV

1

82

Peto Odds Ratio (Peto, Fixed, 95% CI)

4.80 [1.76, 13.06]

4.2 PTFE V Dacron

4

764

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.23 [0.92, 1.65]

4.3 PTFE v PTFE with vein cuff

1

99

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.86 [0.37, 2.02]

5 Primary patency at 60 months Show forest plot

3

316

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.06 [1.28, 3.31]

5.1 PTFE v HUV

1

69

Peto Odds Ratio (Peto, Fixed, 95% CI)

3.75 [1.46, 9.62]

5.2 PTFE v Dacron

2

247

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.67 [0.96, 2.90]

6 Secondary patency at 3 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

6.1 PTFE v HUV

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.0 [0.0, 0.0]

7 Secondary patency at 6 months Show forest plot

2

318

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.32 [0.48, 3.62]

7.1 PTFE v HUV

1

93

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.76 [0.42, 7.44]

7.2 PTFE v Dacron

1

225

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.01 [0.25, 4.13]

8 Secondary patency at 12 months Show forest plot

4

806

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.18 [0.80, 1.74]

8.1 PTFE v HUV

1

93

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.60 [0.43, 5.89]

8.2 PTFE v Dacron

2

581

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.19 [0.76, 1.86]

8.3 PTFE v PTFE with vein cuff

1

132

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.99 [0.39, 2.52]

9 Secondary patency at 24 months Show forest plot

4

700

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.66 [1.18, 2.33]

9.1 PTFE V HUV

1

93

Peto Odds Ratio (Peto, Fixed, 95% CI)

4.01 [1.44, 11.17]

9.2 PTFE v Dacron

2

528

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.54 [1.04, 2.28]

9.3 PTFE v PTFE with vein cuff

1

79

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.22 [0.48, 3.06]

10 Secondary patency at 60 months Show forest plot

2

260

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.86 [1.73, 4.72]

10.1 PTFE v HUV

1

93

Peto Odds Ratio (Peto, Fixed, 95% CI)

3.87 [1.65, 9.05]

10.2 PTFE v Dacron

1

167

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.43 [1.31, 4.53]

11 Limb salvage at 1 month Show forest plot

2

560

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.68 [0.12, 3.98]

11.1 PTFE v Dacron

1

410

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.14 [0.01, 2.20]

11.2 PTFE v PTFE with vein cuff

1

150

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.02 [0.21, 19.72]

12 Limb salvage at 24 months Show forest plot

2

389

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.73 [0.33, 1.62]

12.1 PTFE v Dacron

1

322

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.82 [0.27, 2.48]

12.2 PTFE v PTFE with vein cuff

1

67

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.64 [0.20, 2.04]

Figures and Tables -
Comparison 2. Above‐knee PTFE versus all other graft materials
Comparison 3. Above‐knee heparin bonded Dacron versus all other graft materials

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Primary patency at 12 months Show forest plot

2

294

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.58 [0.34, 0.98]

1.1 HBD v HUV

1

123

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.47 [0.20, 1.12]

1.2 HBD v PTFE

1

171

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.65 [0.34, 1.25]

2 Primary patency at 24 months Show forest plot

2

282

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.62 [0.38, 1.02]

2.1 HBD v HUV

1

117

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.59 [0.26, 1.33]

2.2 HBD v PTFE

1

165

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.64 [0.34, 1.19]

3 Primary patency at 60 months Show forest plot

2

232

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.55 [0.33, 0.93]

3.1 HBD v HUV

1

86

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.07 [0.45, 2.51]

3.2 HBD v PTFE

1

146

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.38 [0.20, 0.72]

Figures and Tables -
Comparison 3. Above‐knee heparin bonded Dacron versus all other graft materials
Comparison 4. Above‐knee externally supported graft versus unsupported graft materials

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Primary patency at 6 months Show forest plot

2

299

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.28 [0.71, 2.31]

1.1 Externally supported dacron versus unsupported dacron

1

253

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.29 [0.69, 2.39]

1.2 Externally supported PTFE versus unsupported PTFE

1

46

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.21 [0.16, 9.25]

2 Primary patency at 12 months Show forest plot

2

286

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.78 [1.06, 2.98]

2.1 Externally supported dacron versus unsupported dacron

1

246

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.71 [0.99, 2.93]

2.2 Externally supported PTFE versus unsupported PTFE

1

40

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.73 [0.49, 15.28]

3 Primary patency at 24 months Show forest plot

2

270

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.08 [1.29, 3.35]

3.1 Externally supported dacron versus unsupported dacron

1

240

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.09 [1.26, 3.46]

3.2 Externally supported PTFE versus unsupported PTFE

1

30

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.01 [0.46, 8.76]

4 Secondary patency at 6 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

5 Secondary patency at 12 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

6 Secondary patency at 24 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

Figures and Tables -
Comparison 4. Above‐knee externally supported graft versus unsupported graft materials
Comparison 5. Above‐knee polyurethane (PUR) versus all other graft materials

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Primary patency at 3 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

2 Primary patency at 6 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

3 Primary patency at 12 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

4 Secondary patency at 3 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

5 Secondary patency at 6 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

6 Secondary patency at 12 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

Figures and Tables -
Comparison 5. Above‐knee polyurethane (PUR) versus all other graft materials
Comparison 6. Below‐knee PTFE versus all other graft materials

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Primary patency at 6 months Show forest plot

4

319

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.12 [0.67, 1.87]

1.1 PTFE v ringed PTFE

1

44

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.47 [0.32, 6.71]

1.2 PTFE v PTFE with vein cuff

2

247

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.00 [0.56, 1.78]

1.3 PTFE v FUSION BIOLINE

1

28

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.96 [0.39, 9.83]

2 Primary patency at 12 months Show forest plot

4

305

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.96 [0.60, 1.55]

2.1 PTFE v Dacron

1

45

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.47 [0.12, 1.79]

2.2 PTFE v PTFE with vein cuff

2

224

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.02 [0.59, 1.76]

2.3 PTFE v ringed PTFE

1

36

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.48 [0.35, 6.24]

3 Primary patency at 24 months Show forest plot

4

250

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.94 [0.56, 1.57]

3.1 PTFE v Dacron

1

40

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.41 [0.12, 1.42]

3.2 PTFE v PTFE with vein cuff

2

182

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.08 [0.58, 2.01]

3.3 PTFE v ringed PTFE

1

28

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.32 [0.31, 5.67]

4 Primary patency at 36 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

4.1 PTFE v PTFE with vein cuff

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.0 [0.0, 0.0]

5 Secondary patency at 3 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

5.1 PTFE v HUV

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.0 [0.0, 0.0]

6 Secondary patency at 6 months Show forest plot

2

242

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.21 [0.69, 2.13]

6.1 PTFE v HUV

1

71

Peto Odds Ratio (Peto, Fixed, 95% CI)

3.01 [1.12, 8.07]

6.2 PTFE v PTFE with vein cuff

1

171

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.79 [0.40, 1.56]

7 Secondary patency at 12 months Show forest plot

3

325

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.48 [0.94, 2.34]

7.1 PTFE v HUV

1

101

Peto Odds Ratio (Peto, Fixed, 95% CI)

2.46 [1.10, 5.49]

7.2 PTFE v PTFE with vein cuff

2

224

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.16 [0.66, 2.03]

8 Secondary patency at 24 months Show forest plot

3

269

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.72 [1.05, 2.80]

8.1 PTFE v HUV

1

88

Peto Odds Ratio (Peto, Fixed, 95% CI)

3.40 [1.45, 7.97]

8.2 PTFE v PTFE with vein cuff

2

181

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.22 [0.67, 2.23]

9 Secondary patency at 36 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

9.1 PTFE v PTFE with vein cuff

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.0 [0.0, 0.0]

10 Limb salvage at 12 months Show forest plot

2

225

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.35 [0.72, 2.55]

10.1 PTFE v PTFE with vein cuff

2

225

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.35 [0.72, 2.55]

11 Limb salvage at 24 months Show forest plot

2

196

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.34 [0.72, 2.49]

11.1 PTFE v PTFE with vein cuff

2

196

Peto Odds Ratio (Peto, Fixed, 95% CI)

1.34 [0.72, 2.49]

Figures and Tables -
Comparison 6. Below‐knee PTFE versus all other graft materials
Comparison 7. Below‐knee heparin bonded Dacron versus all other graft materials

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Primary patency at 3 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

1.1 HBD v PTFE

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.0 [0.0, 0.0]

2 Primary patency at 6 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

2.1 HBD v PTFE

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.0 [0.0, 0.0]

3 Primary patency at 12 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

3.1 HBD v PTFE

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.0 [0.0, 0.0]

4 Primary patency at 24 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

4.1 HBD v PTFE

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.0 [0.0, 0.0]

5 Primary patency at 60 months Show forest plot

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

Totals not selected

5.1 HBD v PTFE

1

Peto Odds Ratio (Peto, Fixed, 95% CI)

0.0 [0.0, 0.0]

Figures and Tables -
Comparison 7. Below‐knee heparin bonded Dacron versus all other graft materials