Scolaris Content Display Scolaris Content Display

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 Surgery versus no surgery, Outcome 1 Any stroke or operative death.
Figures and Tables -
Analysis 1.1

Comparison 1 Surgery versus no surgery, Outcome 1 Any stroke or operative death.

Comparison 1 Surgery versus no surgery, Outcome 2 Ipsilateral ischaemic stroke and any operative stroke or death.
Figures and Tables -
Analysis 1.2

Comparison 1 Surgery versus no surgery, Outcome 2 Ipsilateral ischaemic stroke and any operative stroke or death.

Comparison 1 Surgery versus no surgery, Outcome 3 Disabling or fatal ipsilateral ischaemic or operative stroke and death.
Figures and Tables -
Analysis 1.3

Comparison 1 Surgery versus no surgery, Outcome 3 Disabling or fatal ipsilateral ischaemic or operative stroke and death.

Comparison 2 Subgroup analyses (5‐year cumulative risk of ipsilateral carotid ischaemic stroke, and any stroke or death within 30 days after surgery, according to 3 variables in patients with > 50% carotid stenosis in ECST and NASCET), Outcome 1 Sex.
Figures and Tables -
Analysis 2.1

Comparison 2 Subgroup analyses (5‐year cumulative risk of ipsilateral carotid ischaemic stroke, and any stroke or death within 30 days after surgery, according to 3 variables in patients with > 50% carotid stenosis in ECST and NASCET), Outcome 1 Sex.

Comparison 2 Subgroup analyses (5‐year cumulative risk of ipsilateral carotid ischaemic stroke, and any stroke or death within 30 days after surgery, according to 3 variables in patients with > 50% carotid stenosis in ECST and NASCET), Outcome 2 Age (years).
Figures and Tables -
Analysis 2.2

Comparison 2 Subgroup analyses (5‐year cumulative risk of ipsilateral carotid ischaemic stroke, and any stroke or death within 30 days after surgery, according to 3 variables in patients with > 50% carotid stenosis in ECST and NASCET), Outcome 2 Age (years).

Comparison 2 Subgroup analyses (5‐year cumulative risk of ipsilateral carotid ischaemic stroke, and any stroke or death within 30 days after surgery, according to 3 variables in patients with > 50% carotid stenosis in ECST and NASCET), Outcome 3 Time since last event (weeks).
Figures and Tables -
Analysis 2.3

Comparison 2 Subgroup analyses (5‐year cumulative risk of ipsilateral carotid ischaemic stroke, and any stroke or death within 30 days after surgery, according to 3 variables in patients with > 50% carotid stenosis in ECST and NASCET), Outcome 3 Time since last event (weeks).

Summary of findings for the main comparison. Carotid endarterectomy for symptomatic carotid stenosis

Carotid endarterectomy for symptomatic carotid stenosis

Patients or population: people with carotid stenosis and recent transient ischaemic attacks (TIA) or minor ischaemic strokes in the territory of that artery

Settings: in hospitals with carotid centres1

Intervention: best medical therapy with carotid surgery2,3

Comparison: best medical therapy without carotid surgery2

Outcomes

Illustrative comparative risks* (95% CI)

Relative effect

(95% CI)

Number of
participants

(studies)

Quality of the

evidence

(GRADE)

Comments

Assumed risk

Corresponding risk

Best medical treatment alone

Best medical treatment with carotid surgery

Any stroke or operative death

Near occlusion

RR 0.95

(0.59 to 1.53)

271

(2 studies)

++++

High4

None of these RCTs could be blinded for surgeons or patients due to the nature of the intervention.

22 per 100

20 per 100

70% to 99% carotid stenosis

RR 0.53

(0.42 to 0.67)

1095

(3 studies)

+++Ο

Moderate5

29 per 100

15 per 100

50% to 69% carotid stenosis

RR 0.77

(0.63 to 0.94)

1549

(3 studies)

+++Ο

Moderate5

23 per 100

18 per 100

30% to 49% carotid stenosis

RR 0.97

(0.79 to 1.19)

1429

(2 studies)

++++

High4

21 per 100

20 per 100

< 30% carotid stenosis

RR 1.25

(0.99 ‐ 1.56)

1746

(2 studies)

++++

High4

14 per 100

17 per 100

Ipsilateral ischaemic stroke, and any operative stroke or death

Near occlusion

RR 1.03 (0.57 to 1.84)

271

(2 studies)

++++

High4

None of these RCTs could be blinded for surgeons or patients due to the nature of the intervention.

15 per 100

15 per 100

70% to 99% carotid stenosis

RR 0.47 (0.25 to 0.88)

1095

(3 studies)

+++Ο

Moderate5

23 per 100

10 per 100

50% to 69% carotid stenosis

RR 0.84 (0.60 to 1.18)

1549

(3 studies)

+++Ο

Moderate5

15 per 100

12 per 100

30% to 49% carotid stenosis

RR 0.93 (0.62 to 1.38)

1429

(2 studies)

++++

High4

15 per 100

13 per 100

< 30% carotid stenosis

RR 1.27 (0.80 to 2.01)

1746

(2 studies)

++++

High4

9 per 100

11 per 100

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

CI: Confidence interval; RR: Risk ratio GRADE: GRADE Working Group grades of evidence (see explanations)

1 ECST recruited from 100 centres in 14 European countries, NASCET from 106 centres mainly in the USA and Canada, but including some centres in Europe, Israel, South Africa and Australia, and the VACSP trial from 16 Veterans Affairs medical centres in the USA

2 The recommended dose of aspirin for best medical treatment was 1300 mg in NASCET, 325 mg in the VACSP trial, and unspecified in ECST

3 The median time from randomisation to trial surgery was two days in the VACSP trial, three days in NASCET and 14 days in ECST.

4 All 2 studies (ECST, NASCET) are unconfounded truly randomised controlled trials and conducted on an intention to treat principle with adequate concealment, Few patients were lost to follow up in any of these studies (follow up 99.8‐100%)

5 All 3 studies (ECST, NASCET, VACSP) are unconfounded truly randomised controlled trials and conducted on an intention‐to‐treat principle. However, the allocation concealment was not described in one trial (VACSP). In addition, ECST and NASCET were both stopped after appropriately pre‐specified interim analyses showed that the trial stopping rules had been met. VACSP was also stopped with 193 participants after the results of ECST and NASCET were announced.

Figures and Tables -
Summary of findings for the main comparison. Carotid endarterectomy for symptomatic carotid stenosis
Table 1. The relationships between each subgroup variable and risk of each of the main elements of the primary outcome measure in medical arm.

Subgroups

Ipsilaterial ischaemic stroke in medical group

HR

95% CI (‐)

P

Predefined patient subgroups

Sex (females versus males)

0.79

(0.64 to 0.97)

0.03

Age

< 65 years

1.00

0.001

65 to 74 years

1.23

(1.00 to 1.51)

75+ years

1.70

(1.28 to 2.56)

Time since last event

< 2 weeks

1.00

0.003

2 to 4 weeks

0.80

(0.61 to 1.06)

4 to 12 weeks

0.69

(0.55 to 0.88)

> 12 weeks

0.61

(0.46 to 0.82)

Primary symptomatic event

Ocular only

1.00

< 0.001

Cerebral TIA

1.88

(1.38 to 2.55)

Stroke

2.33

(1.74 to 3.13)

Diabetes

1.31

(1.05 to 1.65)

0.02

Irregular/ulcerated plaque

1.35

(1.11 to 1.64)

0.003

Contralateral ICA occlusion

1.30

(0.09 to 1.88)

0.16

Post‐hoc patient subgroups

Duration of cerebral TIA

1 hour or less

1.00

> 1 hour

1.45

(1.03 to 2.04)

0.03

Previous TIA or stroke

1.20

(0.99 to 1.46)

0.07

Myocardial infarction

1.40

(1.11 to 1.77)

0.004

Angina

1.26

(1.02 to 1.56)

0.03

Treated hypertension

1.39

(1.15 to 1.68)

0.001

Treated hyperlipidaemia

0.78

(0.62 to 0.98)

0.03

Smoking

0.96

(0.80 to 1.16)

0.70

ICA: internal carotid artery
TIA: transient ischaemic attack

Figures and Tables -
Table 1. The relationships between each subgroup variable and risk of each of the main elements of the primary outcome measure in medical arm.
Table 2. The relationships between each subgroup variable and risk of each of the main elements of the primary outcome measure in surgical arm

Subgroups

Perioperative stroke or death in surgery group

HR

95% CI (‐)

P

Predefined patient subgroups

Sex (females versus males)

1.50

(1.14 to 1.97)

0.004

Age

< 65 years

1.00

0.78

65 to 74 years

0.99

(0.76 to 1.32)

75+ years

0.83

(0.49 to 1.41)

Time since last event

< 2 weeks

1.00

0.69

2 to 4 weeks

1.22

(0.78 to 1.90)

4 to 12 weeks

1.14

(0.77 to 1.68)

> 12 weeks

1.28

(0.84 to 1.95)

Primary symptomatic event

Ocular only

1.00

< 0.001

Cerebral TIA

2.62

(1.68 to 4.09)

Stroke

1.91

(1.22 to 3.01)

Diabetes

1.45

(1.05 to 2.02)

0.03

Irregular/ulcerated plaque

1.37

(1.03 to 1.82)

0.03

Contralateral ICA occlusion

2.21

(1.33 to 3.67)

0.002

Post‐hoc patient subgroups

Duration of cerebral TIA

1 hour or less

1.00

> 1 hour

1.24

(0.81 to 1.92)

0.33

Previous TIA or stroke

1.59

(1.21 to 2.09)

0.001

Myocardial infarction

0.87

(0.59 to 1.27)

0.46

Angina

0.67

(0.47 to 0.97)

0.03

Treated hypertension

1.33

(1.02 to 1.74)

0.04

Treated hyperlipidaemia

1.06

(0.74 to 1.51)

0.75

Smoking

0.97

(0.74 to 1.27)

0.81

ICA: internal carotid artery
TIA: transient ischaemic attack

Figures and Tables -
Table 2. The relationships between each subgroup variable and risk of each of the main elements of the primary outcome measure in surgical arm
Table 3. Significance of treatment‐effect modifiers for the relative treatment effect and absolute treatment effect for each of the subgroup variables

Effect of surgery on the risk of the primary outcome (P value)

Relative risk reduction

Absolute reduction in 5‐year actuarial risk

Cox model

5‐year actuarial risk

Predefined patient subgroups

Sex

0.007

0.008

0.003

Age groups

0.09
0.05 (trend)

0.04

0.03

Time since last event groups

0.04
0.006 (trend)

0.05

0.009

Primary symptomatic event

0.21

0.30

0.16

Diabetes

0.51

0.85

0.63

Irregular/ulcerated plaque

0.58

0.23

0.10

Contralateral ICA occlusion

0.30

0.34

0.25

Post‐hoc subgroups

Duration of cerebral TIA

0.44

0.47

0.42

Previous TIA or stroke

0.08

0.23

0.50

Myocardial infarction

0.06

0.02

0.01

Angina

0.08

0.11

0.06

Treated hypertension

0.19

0.29

0.09

Treated hyperlipidaemia

0.63

0.85

0.85

Smoking

0.40

0.40

0.38

ICA: internal carotid artery
TIA: transient ischaemic attack

Figures and Tables -
Table 3. Significance of treatment‐effect modifiers for the relative treatment effect and absolute treatment effect for each of the subgroup variables
Comparison 1. Surgery versus no surgery

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Any stroke or operative death Show forest plot

3

Risk Ratio (M‐H, Fixed, 95% CI)

Subtotals only

1.1 Near occlusion

2

271

Risk Ratio (M‐H, Fixed, 95% CI)

0.95 [0.59, 1.53]

1.2 70% to 99%

3

1095

Risk Ratio (M‐H, Fixed, 95% CI)

0.53 [0.42, 0.67]

1.3 50% to 69%

3

1549

Risk Ratio (M‐H, Fixed, 95% CI)

0.77 [0.63, 0.94]

1.4 30% to 49%

2

1429

Risk Ratio (M‐H, Fixed, 95% CI)

0.97 [0.79, 1.19]

1.5 < 30%

2

1746

Risk Ratio (M‐H, Fixed, 95% CI)

1.25 [0.99, 1.56]

2 Ipsilateral ischaemic stroke and any operative stroke or death Show forest plot

3

Risk Ratio (M‐H, Random, 95% CI)

Subtotals only

2.1 Near occlusion

2

271

Risk Ratio (M‐H, Random, 95% CI)

1.03 [0.57, 1.84]

2.2 70% to 99%

3

1095

Risk Ratio (M‐H, Random, 95% CI)

0.47 [0.25, 0.88]

2.3 50% to 69%

3

1549

Risk Ratio (M‐H, Random, 95% CI)

0.84 [0.60, 1.18]

2.4 30% to 49%

2

1429

Risk Ratio (M‐H, Random, 95% CI)

0.93 [0.62, 1.38]

2.5 < 30%

2

1746

Risk Ratio (M‐H, Random, 95% CI)

1.27 [0.80, 2.01]

3 Disabling or fatal ipsilateral ischaemic or operative stroke and death Show forest plot

3

Risk Ratio (M‐H, Fixed, 95% CI)

Subtotals only

3.1 Near occlusion

2

271

Risk Ratio (M‐H, Fixed, 95% CI)

1.29 [0.51, 3.27]

3.2 70% to 99%

3

1095

Risk Ratio (M‐H, Fixed, 95% CI)

0.40 [0.26, 0.64]

3.3 50% to 69%

2

1502

Risk Ratio (M‐H, Fixed, 95% CI)

0.73 [0.46, 1.15]

3.4 30% to 49%

2

1429

Risk Ratio (M‐H, Fixed, 95% CI)

0.96 [0.60, 1.54]

3.5 < 30%

2

1746

Risk Ratio (M‐H, Fixed, 95% CI)

1.72 [0.99, 2.96]

Figures and Tables -
Comparison 1. Surgery versus no surgery
Comparison 2. Subgroup analyses (5‐year cumulative risk of ipsilateral carotid ischaemic stroke, and any stroke or death within 30 days after surgery, according to 3 variables in patients with > 50% carotid stenosis in ECST and NASCET)

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Sex Show forest plot

2

Risk Difference (M‐H, Fixed, 95% CI)

Subtotals only

1.1 Men

2

1886

Risk Difference (M‐H, Fixed, 95% CI)

‐0.10 [‐0.13, ‐0.06]

1.2 Women

2

832

Risk Difference (M‐H, Fixed, 95% CI)

‐0.03 [‐0.07, 0.02]

2 Age (years) Show forest plot

2

Risk Difference (M‐H, Fixed, 95% CI)

Subtotals only

2.1 < 65

2

1281

Risk Difference (M‐H, Fixed, 95% CI)

‐0.05 [‐0.09, ‐0.01]

2.2 65 to 74

2

1143

Risk Difference (M‐H, Fixed, 95% CI)

‐0.07 [‐0.12, ‐0.03]

2.3 > 75

2

294

Risk Difference (M‐H, Fixed, 95% CI)

‐0.17 [‐0.26, ‐0.09]

3 Time since last event (weeks) Show forest plot

2

Risk Difference (M‐H, Fixed, 95% CI)

Subtotals only

3.1 < 2

2

624

Risk Difference (M‐H, Fixed, 95% CI)

‐0.17 [‐0.24, ‐0.11]

3.2 2 to 4

2

483

Risk Difference (M‐H, Fixed, 95% CI)

‐0.09 [‐0.15, ‐0.02]

3.3 4 to 12

2

1058

Risk Difference (M‐H, Fixed, 95% CI)

‐0.05 [‐0.09, ‐0.01]

3.4 > 12

2

553

Risk Difference (M‐H, Fixed, 95% CI)

0.00 [‐0.06, 0.06]

Figures and Tables -
Comparison 2. Subgroup analyses (5‐year cumulative risk of ipsilateral carotid ischaemic stroke, and any stroke or death within 30 days after surgery, according to 3 variables in patients with > 50% carotid stenosis in ECST and NASCET)