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Perianal injectable bulking agents as treatment for faecal incontinence in adults

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Abstract

Background

Faecal incontinence is a complex and distressing condition with significant medical and social implications. Injection of perianal bulking agents has been used to treat the symptoms of passive faecal incontinence. However, various agents have been used without a standardised technique and the supposed benefit of the treatment is largely anecdotal with a limited clinical research base.

Objectives

To determine the effectiveness of perianal injection of bulking agents for the treatment of faecal incontinence in adults.

Search methods

We searched the Cochrane Incontinence Group Specialised Register of trials (25 May 2012), ZETOC (3 May 2012), clinical trials registries (3 May 2012) and the reference lists of relevant articles.

Selection criteria

All randomised or quasi‐randomised controlled trials comparing the use of injectable bulking agents for faecal incontinence with any alternative treatments or placebo were reviewed to evaluate the therapeutic effects. Case‐control and cohort studies were also reviewed to assess risks and complications associated with the treatments.

Data collection and analysis

Two review authors (YM and CN) assessed the methodological quality of eligible trials and independently extracted data from the included trials using a range of pre‐specified outcome measures.

Main results

Five eligible randomised trials with a total of 382 patients were identified. Four of the trials were at an uncertain or high risk of bias.

Most trials reported a short term benefit from injections regardless of the material used, including placebo saline injection. One study demonstrated dextranomer in stabilised hyaluronic acid (NASHA Dx) to be more effective than sham injection but with more adverse effects. Dextranomer in stabilised hyaluronic acid (NASHA Dx) was better than sham injections at six months (65/136, 48% versus 48/70, 69% participants not improved, defined as less than 50% reduction in incontinence episodes, RR 0.70, 95% CI 0.55 to 0.88; with more incontinence free days (3.1 days compared with 1.7 in the sham treatment group, MD 1.40 days, 95% CI 0.33 to 2.47). Another study comparing silicone material (PTQ™) to saline injections was too small to demonstrate a clinical benefit compared to the control injection of normal saline.

A silicone biomaterial (PTQ™) was shown to provide some advantages and was safer in treating faecal incontinence than carbon‐coated beads (Durasphere®) in the short term.

Similarly, there were short term benefits from injections delivered under ultrasound guidance compared with digital guidance.

No long term evidence on outcomes was available and further conclusions were not warranted from the available data. None of the studies reported patient evaluation of outcomes and thus it is difficult to gauge whether the improvement in incontinence scores matched practical symptom improvements that mattered to the patients.

Authors' conclusions

One large randomised controlled trial has shown that this form of treatment using dextranomer in stabilised hyaluronic acid (NASHA Dx) improves continence for a little over half of patients in the short term. However, the number of identified trials was limited and most had methodological weaknesses.

Plain language summary

Injection of bulking material around the anus (back passage) for the treatment of faecal incontinence in adults

Loss of bowel control, also known as faecal incontinence, can be a devastating problem. It affects men and women of all ages in up to 15% of the adult population. Faecal incontinence can radically affect everyday life as many people become almost house bound, being unable to undertake simple tasks, such as shopping, because they are worried about faecal leakage.

Faecal incontinence may be due to a problem with the two muscles around the anus (back passage). These muscles can be damaged or become weak due to injury during child birth or operations to treat anal conditions such as haemorrhoids (piles) and fistulas (abnormal channels between the skin and back passage). The anal muscles then become unable to hold back the stools until the person reaches the toilet. The inner ring or internal anal sphincter muscle normally keeps the anus closed at all times except when opening the bowel, preventing passive leakage of stool. A treatment has been developed to treat faecal incontinence, which involves injecting a substance into or near this muscle to make it bulkier so that the anus closes better. It has been advocated as a simple and safe option.

In this review, one large trial demonstrated that injection of dextranomer stabilised in hyaluronic acid improves the symptoms of incontinence in the short term in little over half of those who received the treatment. The other four trials reviewed were of limited value because they were generally poor in methodological quality and small in size. There are no reported long term results for this treatment.

Authors' conclusions

Implications for practice

A single large trial demonstrated that perianal injection of a bulking agent is effective in treating faecal incontinence for up to one year. In other reported studies to date, patients experienced an improvement in symptoms in the short term. No studies evaluated the long term benefit on symptoms of passive faecal incontinence. 

A review of all the observational non‐randomised studies published to date indicates that the injection of biomaterial appears relatively safe and although minor adverse events are relatively common, they are probably unlikely to do any serious harm. However, in view of the poor quality of reporting complications and small sample sizes these conclusions can only be tentative.

Implications for research

There is a need for more well‐designed randomised controlled trials with adequate sample sizes, validated outcome measures (particularly those reported by participants) and long term follow up. The longest follow up in the reviewed trials was 12 months. Currently it is unknown whether the injection of bulking agents causes any medium term or long term benefit or adverse events. Therefore systematic long term monitoring of participants is necessary together with evaluation of the efficacy and location of the material by endoanal ultrasonography. Further work on the mechanism for any benefit is also needed.

Adoption of agreed definitions or classification of the type of faecal incontinence is required to improve comparability of the studies and facilitate a robust systematic review of trials. In particular, the clinical relevance of the most commonly used primary endpoint, an incontinence score, remains to be validated in terms of patient evaluation of the effect of treatment.

Background

Description of the condition

Faecal incontinence is defined as involuntary loss of solid or liquid faeces (stools, motions). It is a distressing condition with significant social and medical implications. The prevalence of faecal incontinence may range from 1.6% to 15% depending on how it is defined, age and whether the patients are community‐dwelling or living in an institution (Whitehead 2009). The symptom has a major impact on quality of life and activities of daily living, in many cases causing extreme embarrassment and discomfort. 

Faecal incontinence has many diverse causes. The maintenance of continence is a complex mechanism which consists of the interaction of an intact and functional anal sphincter complex, the consistency of the faeces, adequate cognitive ability and physical mobility, and bowel motility. Any impairment of these elements can result in incontinence.

The symptoms of incontinence have traditionally been divided into two symptom groups, urge and passive incontinence. Urge incontinence is loss of faeces following the inability to resist the urge to defaecate for long enough to reach a toilet and is primarily associated with external anal sphincter (EAS) dysfunction. Passive faecal incontinence is involuntary loss of faeces without the urge to defaecate and is predominantly associated with internal anal sphincter (IAS) dysfunction (Engel 1995 ). The multiple possible causes and contributing factors to faecal incontinence are reviewed elsewhere (Bharucha 2010; NICE 2007; Rao 2004). This review focuses specifically on treatment for passive faecal incontinence secondary to IAS weakness.

The causes of IAS dysfunction can be classified into two main groups. One is a morphologically intact but functionally weak IAS and the second is a structurally damaged IAS.

  • A structurally intact but weak IAS may be due to primary degeneration or systemic disease such as systemic sclerosis (Vaizey 1997). Radiotherapy can damage the myenteric plexus leading to diminished IAS function (Da Silva 2003).

  • Destruction of or structural damage to the IAS can be caused by anal surgery such as anal dilatation, sphincterotomy, fistula surgery and haemorrhoidectomy (Lindsey 2004). Obstetric injury such as a third or fourth degree vaginal tear may extend beyond the vagina to damage the IAS and this direct anal trauma may disrupt the structure of the IAS (Wheeler 2007).

Symptoms are likely to be exacerbated by loose faeces or incomplete rectal evacuation. The exact cause of passive soiling for an individual patient is often unclear.

Currently, the treatment for faecal incontinence associated with IAS dysfunction remains challenging. Medical management, such as modifying the consistency of the faeces by anti‐diarrhoeal agents (Cheetham 2003) or pelvic floor muscle training with or without biofeedback, is effective to a certain extent (Norton 2012) but many people do not find such conservative treatment to be an ideal long term solution. The IAS is not amenable to direct surgical repair (Felt‐Bersma 1996; Leroi 1997; Morgan 1997) and major surgery, such as implantation of an artificial bowel sphincter or dynamic graciloplasty, is associated with significant morbidity (Christiansen 1999; Wexner 1996). Such interventions may be disproportionate to symptoms. Sacral nerve stimulation is an emerging treatment option for faecal incontinence but has not yet been proven to be effective for IAS dysfunction. There is, therefore, a large gap between conservative and major surgical options for treating passive faecal incontinence.

This review focused specifically on one treatment that has been developed for the symptom of passive faecal incontinence secondary to IAS disruption or weakness. Although there has been an exploratory study injecting somatic muscle cells, using a similar technique to that to either fill in a defect or regenerate muscles for EAS injury (Frudinger 2010), it is not included within the scope of this review.

For further information on other interventions for faecal incontinence treatment, please refer to Cochrane reviews on:

  • surgery for faecal incontinence in adults (Brown 2010),

  • sacral nerve stimulation for faecal incontinence and constipation in adults (Mowatt 2007),

  • plugs for containing faecal incontinence (Deutekom 2012),

  • electrical stimulation for faecal incontinence in adults (Hosker 2007),

  • drug treatment for faecal incontinence in adults (Cheetham 2003),

  • biofeedback or sphincter exercises, or both, for the treatment of faecal incontinence in adults (Norton 2012), and

  • absorbent products for moderate‐heavy urinary or faecal incontinence, or both, in women and men (Fader 2008).

Description of the intervention

Injection of bulking agents has emerged as a new treatment for faecal incontinence following on from reported success in treating urinary incontinence. The concept is to inject a biocompatible material in order to close the anal canal to avoid faecal incontinence. This may be performed under local, regional or general anaesthetic, and can also be used as a 'minimally invasive' treatment in an outpatient clinic setting.

Ten different materials have been used (autologous fat, Teflon, bovine glutaraldehyde cross‐linked collagen, carbon‐coated zirconium beads, polydimethylsiloxane elastomer, dextranomer in non‐animal stabilised hyaluronic acid, hydrogel cross‐linked with polyacrylamide, porcine dermal collagen, synthetic calcium hydroxylapatite ceramic microspheres, and polyacrylonitrile in cylinder form). The material can be injected either via the perianal skin or via the anal mucosa. The injection may be guided by the surgeon's finger in the anal canal or by ultrasound visualisation of placement.

How the intervention might work

The aim is to inject a biocompatible material into the submucosa of the anal canal or into the space between the anal sphincters in order to bulk out the tissue around the anal canal and approximate the anal mucosa, thereby closing the anal canal or raising the pressure inside the anal canal to prevent faecal incontinence.

Why it is important to do this review

This treatment is becoming widespread following the results of observational studies as it is potentially attractive in its simplicity and minimal invasiveness. However, it is not clear if this intervention is effective, cost effective or if any effect persists in the long term. There is no consensus regarding the indications for the treatment nor the choice of optimum material. There is little information on possible adverse events (either acute such as pain and infection or chronic such as new difficulties with evacuation). We aimed to systematically review the trials published to date and combine best evidence currently available oto base recommendations for clinical practice. 

Objectives

The objective of this review was to determine if the injection of bulking agents is better than currently available treatments or no treatment for faecal incontinence in adults in terms of effectiveness, complications and quality of life.

The following comparisons were made:

1. injection of bulking agents versus no intervention or a placebo or sham injection;

2. injection of bulking agent versus any single or combination conservative treatment (such as biofeedback, diet, anal plug, anti‐diarrhoeal medication, pelvic floor exercise);

3. injection of bulking agent versus another minimally invasive or surgical intervention;

4. one type of bulking agent versus another type of bulking agent;

5. one technique of administration or injection of the agent versus another technique;

6. larger volumes of agent versus smaller volumes;

7. safety outcomes related to injectable bulking agents, information from both the included trials and non‐randomised studies.

Methods

Criteria for considering studies for this review

Types of studies

All randomised or quasi‐randomised controlled trials comparing the use of injectable bulking agents for faecal incontinence due to internal anal sphincter (IAS) dysfunction with any alternative treatments or placebo. Case‐control and cohort studies were also reviewed to assess the safety (risks and complications) of the treatment.

Types of participants

All adults with faecal incontinence of any severity and any cause. Any trials in children were excluded as the causes of incontinence are more diverse and complex (for example congenital disorders).

Types of interventions

Injection of bulking agents (biomaterials and autologous tissues) into the anal submucosa or intersphincteric space, either via the anal mucosa or perianally, as a treatment for faecal incontinence. This included injection of autologous fat, Teflon, bovine glutaraldehyde cross‐linked collagen, carbon‐coated zirconium beads, polydimethylsiloxane elastomer, dextranomer in non‐animal stabilised hyaluronic acid, hydrogel cross‐linked with polyacrylamide, porcine dermal collagen, microballoons, polyacrylonitrile in cylinder form and synthetic calcium hydroxylapatite ceramic microspheres, and any other materials found in the literature search.

The comparison intervention could include no treatment or placebo or sham treatment, another bulking agent, conservative treatment (for example biofeedback, anal plug, diet, anti‐diarrhoeal medication, pelvic floor exercise), minimally invasive treatment (for example sacral nerve stimulation, radio‐frequency ablation) and surgical intervention.

Different injection techniques were also compared to determine whether one technique was superior to another.

Types of outcome measures

There are a range of outcome measures which can be used to assess the effectiveness and safety of the treatment as listed below.

Primary outcomes

  • Change in incontinence scores (e.g. Wexner or Cleveland Clinic Florida Fecal Incontinence Score (CCFIS) or St Mark's incontinence score)

Secondary outcomes
Patient reported outcomes

Subjective assessment of change by the patient (improved, no change, or deterioration in incontinence); symptoms; ability to conduct activities of daily living; satisfaction or dissatisfaction with treatment; need for additional therapy (need to wear absorbent products for incontinence, use of drugs, dietary changes, repeat procedure)

Clinician observation

Physiological measures (maximum resting anal pressure, maximum squeeze anal pressure, mucosal electrosensitivity). Evidence of migration of material by imaging or examination. Further surgical intervention for faecal incontinence (including formation of colostomy)

Quality of life

Generic and condition‐specific change in quality of life scores such as Fecal Incontinence Quality of Life Scale (FIQL); measures of psychological well‐being

Adverse effects

Post‐operative complications (e.g. bleeding, infection, injection site or anal pain or discomfort, new evacuation difficulty)

Health economics

Length of hospital stay, costs

Search methods for identification of studies

This review has drawn on the search strategy developed by the Cochrane Incontinence Group. We did not impose any language or other limits on the searches.

Electronic searches

Relevant trials were identified from the Incontinence Group Specialised Register of controlled trials, which is described under the Incontinence Group module in The Cochrane Library. The register contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, CINAHL and handsearching of journals and conference proceedings. The date of the most recent search of the Specialised Register for this review was 25 May 2012.

The trials in the Incontinence Group Specialised Register are also contained in CENTRAL.

The terms used to search the Incontinence Group Specialised Register are given below:

(({DESIGN.CCT*} OR {DESIGN.RCT*}) AND {TOPIC.FAECAL*} AND {INTVENT.SURG.INJECT*})

(All searches were of the keyword field of Reference Manager 12, ISI ResearchSoft).

Additional trials were sought by one of the review authors from the UK National Research Register, Controlled Clinical Trials and the ZETOC database of conference abstracts (searching specifically the American, European, Australasian and UK Societies of Colorectal Surgeons meeting abstracts for the past 10 years). The search was conducted on 3 May 2012 using appropriate free text and MeSH terms by adapting terms drawn from the existing search strategies for the Incontinence Review Group to meet the objectives of this review. Keywords used included: fecal incontinence, durasphere, silicone, collagen, biocompatible materials, polydimethylsiloxane, polyacrylamide, dextranCopolymer, hyaluronicAcid, polyacrylonitrile, AdverseEvents.

Searching other resources

The review authors also searched all the reference lists of relevant articles.

Data collection and analysis

Two review authors (YM, CN) examined all the citations and abstracts derived from the above search strategy. Reports of relevant trials were retrieved in full. Data were processed as described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Data were analysed using Review Manager (RevMan Version 5.1.7).

Selection of studies

The titles and abstracts of all studies identified from the above search strategy were independently assessed for potential eligibility by two review authors (YM, CN) and the full papers were obtained for all studies considered eligible. Any disagreements were resolved by consultation with the third review author (SL). Randomised controlled trials (RCTs) and quasi‐RCTs only were included for the efficacy review.

All other study designs (for example case series of any design, any length of follow up and sample size) were reviewed for reports of adverse events and complications. This review for adverse events forms a separate section of the review and specifically alerts the reader to the different search method employed.

Data extraction and management

Data extraction from the included trials were undertaken independently by the two review authors (YM, CN). Data from RCTs and quasi‐RCTs were processed as described in the Cochrane Handbook for Systematic Reviews of Interventions (Version 5.1.0) (Higgins 2011). Data were analysed using the RevMan analyses statistical programme in Review Manager. Data on adverse events and complications were extracted and entered onto an Excel spreadsheet for review and analysis by all three review authors.

Assessment of risk of bias in included studies

The methodological quality of all included RCTs and quasi‐RCTs was evaluated by two review authors (YM and CN) using the criteria recommended by the Cochrane Incontinence Review Group to assess risk of bias. In particular, trials were assessed for randomisation procedure, blinding, adequacy of allocation concealment and attrition bias.

Measures of treatment effect

If appropriate, the results of included studies were combined for each outcome in a formal meta‐analysis to produce an overall estimate of treatment effect. For dichotomous data the risk ratio (RR) and 95% confidence interval (CI) were derived using a fixed‐effect model, and for continuous data weighted mean differences (WMD), weighted by the inverse of the variance, were calculated.

Unit of analysis issues

There were no non‐standard designs.

Dealing with missing data

Trials were assessed as to whether the results were reported on attrition bias, and if not the number and reasons for withdrawals and drop‐outs were sought.

Assessment of heterogeneity

Analysis of variation across the trials was considered if the number of available trials was sufficient to conduct such an assessment.

Assessment of reporting biases

The potential bias was reported as published.

Data synthesis

It was intended to perform a meta‐analysis using a fixed‐effect model if data were available.

Subgroup analysis and investigation of heterogeneity

If data allowed, subgroup analyses would have been undertaken according to: cause of incontinence; sphincter integrity; gender; and injection technique.

Sensitivity analysis

Sensitivity analyses would have been performed if data allowed, such as according to the quality (risk of bias) of trials.

Results

Description of studies

Five randomised trials were included in this review. In total, 382 patients were randomised (Graf 2011; Maeda 2008; Siproudhis 2007; Tjandra 2004; Tjandra 2009).

Results of the search

Twenty records were identified by the search of which four were not relevant and were excluded. Sixteen full text reports were assessed and one was excluded as it was not a randomised trial. Eight reports of five studies were eligible for inclusion in the review. Additionally, there were seven studies that still appeared to be ongoing: one (Smart 2008) was a communication about an ongoing trial and the results were not yet available in the public domain at the time of the search; one study (NCT00762047 2009) appeared to have been terminated in 2009 (reasons unknown, trialists contacted for details); and three were ongoing studies for EAS injuries using cell therapy. The flow of study selection is summarised in Figure 1.


PRISMA study flow diagram,

PRISMA study flow diagram,

Included studies

The five randomised trials (Graf 2011; Maeda 2008; Siproudhis 2007; Tjandra 2004; Tjandra 2009) included a total of 382 patients. Further details are in the Characteristics of included studies table.

The participants in all five RCTs had internal anal sphincter (IAS) dysfunction or passive faecal incontinence and were reported to have failed previous conservative management with anti‐diarrhoeal drugs and pelvic floor muscle training or biofeedback (although this was not standardised and generally not reported in any detail).

The interventions tested were:

  • hydrogel cross‐linked with polyacrylamide (Bulkamid) (Maeda 2008);

  • porcine dermal collagen (Permacol) (Maeda 2008);

  • polydimethylsiloxane elastomer implants (Siproudhis 2007);

  • silicone biomaterial (PTQ) injected between the two anal sphincters (Tjandra 2009);

  • carbon‐coated beads injected into the anal submucosa (Durasphere) (Tjandra 2009);

  • two different injection techniques (endoanal ultrasound guidance or digital guidance) using a silicone biomaterial (PTQ) (Tjandra 2004);

  • dextranomer in stabilised hyaluronic acid (NASHA Dx) (Graf 2011).

The control intervention in two trials were:

  • saline (Siproudhis 2007);

  • sham injection (mimicking active treatment but without injection of any substance) (Graf 2011).

The injection sites were:

Excluded studies

See the Characteristics of excluded studies table. One study was not an RCT (Dehli 2007).

Risk of bias in included studies

Risk of bias was assessed in summary (Figure 2) and in each trial (Figure 3).


Methodological quality graph: review authors' judgements about each methodological quality item presented as percentages across all included studies.

Methodological quality graph: review authors' judgements about each methodological quality item presented as percentages across all included studies.


Methodological quality summary: review authors' judgements about each methodological quality item for each included study.

Methodological quality summary: review authors' judgements about each methodological quality item for each included study.

Allocation

Two trials gave sufficient details about the randomisation process to suggest freedom from bias (sequence generation in a central registry) (Graf 2011; Tjandra 2009). The quality of allocation concealment was judged to be unclear in three trials.

Blinding

In two trials (Graf 2011; Siproudhis 2007), the patients and the outcome assessors were blinded to treatment allocation. The other three trials did not specify whether the assessor was different from the person involved in the treatment.

It was not possible to blind the surgeons in any of the trials as the interventions were different.

Incomplete outcome data

Withdrawals and intention to treat

Three trials reported no drop‐outs, one presented a flow of patients with figures (Graf 2011), and one had a high drop‐out rate (Tjandra 2004). From the number of people included at the start and the results of the trial, four trials analysed data on an intention‐to‐treat basis (Graf 2011; Maeda 2008; Siproudhis 2007; Tjandra 2009) whilst one trial conducted an available case analysis (Tjandra 2004).

Follow up

Follow up varied from three to 12 months. No long term results were presented.

Selective reporting

Review authors considered there was no evidence of selective reporting.

Other potential sources of bias

There are six ongoing trials (Dehli 2007; Dehli 2009; Draganic 2008; EUCTR2010‐021463‐32‐AT 2011; Michot 2012; Norderval 2012). Five studies are ongoing with three of them aiming to regenerate muscles by cell therapy for external anal sphincter injuries, hence they are not under the scope of the current review. One study has been completed and is under preparation for publication (personal communication).

Effects of interventions

1. Injection of bulking agent versus placebo or sham injection

Two trials addressed this comparison.

Siproudhis et al (Siproudhis 2007) compared a silicone biomaterial (polydimethylsiloxane elastomer, PTQ) with a (control) normal saline injection into the intersphincteric space. The trial was too small to detect differences in any outcomes, such as failure rate (17/22, 77% versus 16/22, 72% in the control group, RR 1.06, 95% CI 0.75 to 1.50; Analysis 1.1); use of pads (Analysis 1.3) or Wexner score (Analysis 1.5). In addition, the subjective perception of treatment success was low in both groups (23% versus 27%, P = 0.73).

The study by Graf et al (Graf 2011) compared injection of dextranomer stabilised in hyaluronic acid (NASHA Dx) against sham injection (injection without actual substance). The primary endpoint was a response to treatment which was defined as a 50% or greater reduction in the number of incontinence episodes. There was a statistically significant difference between the treatment and control groups at six months (65/136, 48% versus 48/70, 69% participants not improved, defined as less than 50% reduction in incontinence episodes, RR 0.70, 95% CI 0.55 to 0.88; Analysis 1.2). Participants in the active group had statistically significantly more incontinence free days at six months (3.1 days compared with 1.7 in the sham treatment group, MD 1.40 days, 95% CI 0.33 to 2.47; Analysis 1.4). However, this difference was not shown at three months. Secondary endpoints such as number of faecal incontinence episodes, CCFIS at three and six months and FIQOL at 12 months did not show any difference except for one domain of FIQOL between the active and sham treatment groups. While there were fewer adverse events in the control group (128/136, 94% in the active group versus 29/70, 41% in the control group, RR 2.27, 95% CI 1.71 to 3.01; Analysis 1.6.2), only two in the active group were regarded as serious (rectal and prostate abscesses).

2. Injection of bulking agent versus conservative treatment

No trials were found.

3. Injection of bulking agent versus another minimally invasive or surgical intervention

No trials were found.

4. One type of bulking agent versus another type

Two trials addressed this comparison (Maeda 2008; Tjandra 2009).

In the trial by Tjandra and colleagues (Tjandra 2009), injection of the silicone biomaterial polydimethylsiloxane elastomer (PTQ™) and carbon‐coated beads (Durasphere®) were compared. While participants in both groups reported an improvement in Wexner's score and quality of life over the study period up to 12 months, the silicone material was better than the carbon‐coated beads in terms of: faecal incontinence at six and 12 months (for example at 12 months, RR 0.15, 95% CI 0.04 to 0.60; Analysis 2.1); Wexner's incontinence score at six and 12 months (for example at 12 months, MD ‐3.20, 95% CI ‐4.91 to ‐1.49; Analysis 2.2); and quality of life (lifestyle) index at six months (MD ‐0.56, 95% CI ‐1.01 to ‐.011; Analysis 2.3). There were more adverse effects (4/20 in the silicone group versus 8/20 in the carbon‐coated bead group; Analysis 2.4); one serious event occurred in the carbon‐coated bead group only (Analysis 2.5). It was assumed that there were no drop‐outs, though this was not explicitly stated.

Another trial with only 10 participants (Maeda 2008) compared injection of hydrogel cross‐linked with polyacrylamide (Bulkamid™) and porcine dermal collagen (Permacol™). In the hydrogel group incontinence scores improved from a median of 15 to 12 at six weeks and this was maintained at six months. In the porcine dermal collagen group, the baseline median score improved from 16 to 14 at six weeks but deteriorated to 15 at six months. The trial was too small to detect differences between the groups in terms of faecal incontinence becoming worse (Analysis 2.1), the overall St Mark's incontinence score, or the faecal incontinence quality of life score, but data were not provided in a form suitable for analysis (medians and no SDs).

5. One technique of administration of agent compared to another technique

One trial (Tjandra 2004) compared a silicone biomaterial, polydimethylsiloxane elastomer (PTQ™), injection under endoanal ultrasound guidance versus digital (finger) guidance. Using a criterion of greater than 50% decrease (improvement) in the Wexner scale, the ultrasound technique was better than the digital technique (RR 0.53, 95% CI 0.31 to 0.92; Analysis 3.1, Analysis 3.2) and improved the Quality of Life (lifestyle) index at six months (MD ‐0.60, 95% CI ‐0.92 to ‐0.28; Analysis 3.3). The only reported adverse effect, discomfort at the injection site, was rare (2/42 and 4/40 participants; Analysis 3.4). However, many of the data were reported in a form not suitable for analysis (medians and no SDs), the follow up was short (12 months), and there was a high drop‐out rate (by 12 months, 32/42 and 35/40 respectively).

6. Larger volumes of agent versus smaller volumes

No trials were found.

7. Safety data in included RCTs and other non‐randomised studies

Adverse effects were reported in four of the five included trials (Graf 2011; Siproudhis 2007; Tjandra 2004; Tjandra 2009). In the randomised trials included in this review, one trial (Siproudhis 2007) reported 18 adverse effects in nine people (Analysis 1.6). Six out of 22 people injected with silicone biomaterial (PTQ™) complained of pain at the implant site, whilst two out of 22 people in the saline group complained of pain. Anal inflammation was noted in two people in the silicone biomaterial injection group compared to none in the normal saline group. The severity of these adverse effects was categorised as 'not serious' but the duration of the events was not reported. In the trial reported by Graf et al (Graf 2011), patients treated with dextranomer stabilised in hyaluronic acid (NASHA Dx) reported 128 adverse events (number of patients not stated) whilst 29 events (number of patients not stated) were recorded in the sham treatment group (Analysis 1.6). The most common event was proctalgia (19/136 versus 2/70) followed by injection site bleeding (7/136 versus 12/70) and rectal haemorrhage (10/136 versus 1/70). Two serious events were reported in the active treatment group, one was a prostatic abscess resolved by antibiotic treatment and the other was a rectal abscess which required surgical drainage. The trial comparing silicone biomaterial (PTQ™) and carbon‐coated beads (Durasphere®) (Tjandra 2009) reported no septic or significant complications in patients injected with PTQ™, although there were four occurrences of bruising. In contrast, patients who had a Durasphere® injection complained of rectal pain (1/20), erosion of rectal mucosa (2/20) and type III hypersensitivity reaction in small joints and skin (1/20) (Analysis 2.4). One of these type III hypersensitivities was judged to be serious and resulted in hospital admission for seven days (Analysis 2.5). The trial comparing injection techniques (Tjandra 2004) reported minor discomfort in two of 42 patients who had injections with ultrasound guidance and four of 40 patients with digital guidance (Analysis 3.4); in one patient this persisted for six weeks. There were no reports of other serious adverse effects (Analysis 3.5).

The occurrence of complications was also investigated in all non‐randomised studies found to date and is summarised in Table 1. In general, the complications were poorly reported.The severity and duration of complications were rarely reported and in some studies there was no mention of whether or not there had been any complications. The complications were mostly minor (discomfort, pain, bleeding, leakage of injected material). One rectovaginal fistula was reported although it was not clear if this was related to the injection. The reason for discontinuation of one study (NCT00762047 2009) is unclear and there is no information on adverse events in this study.

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Table 1. Summary of complications

Agent

Authors and Year

No of patients

Injection route

Total volume

Complications

Number of adverse effects/Number of participants

Autologous fat

Shafik 1995

14

Submucosal

15‐20ml

Reports that there were no complications

0/14

Bernardi 1998

1

Perianal

130ml

Reports that there were no complications

0/1

Bioplastique™/PTQ™

Malouf 2001

10

Perianal

5‐11.5ml

4 anal canal ulcer, 1 injection site pain, 1 leakage of injected material

6/10

Tjandra 2004

82

Perianal

10.0ml

6 minor discomfort at injection site (4: digital guidance group, 2: ultrasound guidance group)

6/82

Chan 2006

7

Perianal

Not mentioned

Reports that there were no complications

0/7

de la Portilla 2007

20

Perianal

7.5ml

Not reported

Not reported

Maeda 2007

6

Perianal

7.5ml

1 recto‐vaginal fistula

1/6

van der Hagen 2007

24

Perianal

7.5ml

Not reported

Not reported

Gett 2007

37

Not mentioned

Not mentioned

4 perianal abscess required surgical drainage

4/37

Siproudhis 2007

22

Perianal

7.5ml

6 pain at the implant site, 2 anal inflammation

8/22

Soerensen 2009

33

Perianal

7.5ml

Reports that there were no complications

0/33

Tjandra 2009

20

Perianal

10.0ml

4 bruising

4/20

Bartlett 2009

74

Perianal

10.0ml

9 minor complications

9/74

van Wunnik 2012

50

Perianal

Not mentioned

2 local giant cell foreign body reaction

2/50

Bulkamid™

Maeda 2008

5

Perianal

median 9ml (8‐9)

Reports that there were no complications

0/5

Coaptite®

Ganio 2008

10

Perianal

4ml

1 leakage of Coaptite®

1/10

Contigen®

Kumar 1998

17

Submucosal

2ml

Reports that there were no complications

0/17

Stojkovic 2006

73

Submucosal

5ml

Not reported

Not reported

Durasphere®/ACYST‐TM

Weiss 2002

7

Submucosal

average 6.8ml

Not reported

Not reported

Davis 2003

18

Submucosal

mean 1.28ml at 1‐4 sites

2 anal discomfort, 1 exacerbation of pruritis ani, 2 passage of injected Durasphere via anus

5/18

Altomare 2008

33

Submucosal

median 8.8ml (2‐19ml)

2 anal pain, 1 Durasphere® leakage, 2 material migration

5/33

Aigner 2009

11

Perianal

mean 9ml (8‐12ml)

Local pain (most frequent, no numbers reported), 3 passage of Durasphere®

At least 3/11

Tjandra 2009

20

Submucosal

10.0ml

4 bruising, 2 erosion of rectal mucosa, 1 rectal pain, 1 type III hypersensitivity

8/20

Gatekeeper™ (polyacrylonitrile)

Ratto 2011

14

Perianal

1 cylinder (length 21mm, diameter 1‐2mm)x4

Reports that there were none.

0/14

NASHA™Dx

Dehli 2007

4

Submucosal

5.6ml

1 bleeding settled with compression, 1 anal pain, 1 tenesmus. All complications settled within 2‐7 days after procedure.

3/4

Danielson 2009

34

Submucosal

4ml

Pain (26% during 1st injection procedure, 55% for second treatment), 3 suspected inflammation of anal canal, 2 sensation of obstructed defaecation

At least 5/34

Graf 2011

136

Submucosal

4‐8ml

128 adverse events in total. Two serious events, one prostatic abscess and one rectal abscess.

128/136

Dodi 2010

115

Submucosal

up to 4ml

154 adverse events, including 20 serious events such as abscess and haemorrhage

154 adverse events by 70 patients

Permacol™

Smart 2005

7

Submucosal

Not mentioned

Reports that there were no complications

0/7

Maeda 2008

5

Perianal

median 15ml (15‐17.5)

Reports that there were no complications

0/5

Saline

Siproudhis 2007

22

Perianal

7.5ml

2 pain at the implant site

2/22

Synthetic collagen

Ullah 2011

11

Submucosal

Not specified

One death unrelated to the treatment

1/11

Teflon®

Shafik 1993

11

Submucosal

10ml

Not reported

Not reported

Urosurge®

Feretis 2001

6

Submucosal

up to 5 balloons

1 bleeding, 1 lost balloon after 2 months (potential spontaneous burst)

2/6

Bioplastique™/PTQ™: Silicone biomaterial

Bulkamid™: Hydrogel cross‐linked with polyacrylamide

Coaptite®: Calcium hydroxylapatite

Contigen®: Synthetic bovine collagen

Durasphere®/ACYST‐TM: Carbon‐coated microbeads

NASHA™Dx: Stabilized nonanimal hyaluronic acid with dextranomer

Permacol™: Porcine dermal collagen

Teflon®: Polytetrafluoroethylene

Urosurge®: Expandable silicone microballoon

Most studies do not appear to have systematically and prospectively collected data on adverse events, but instead reported those which came to the investigators' attention.

Discussion

Since the publication of the last version of this review, a large adequately‐sized trial has emerged which demonstrated the short term efficacy of dextranomer stabilised in hyaluronic acid (NASHA Dx) injection for faecal incontinence. The study showed 52% of patients in the active treatment group had a 50% or greater reduction in the number of incontinence episodes compared to 31% of those who had a sham injection. Although this definition of successful treatment is rather arbitrary, there were significantly more patients who achieved this primary outcome compared to sham injection.

It is interesting to note that nearly 30% of the patients in the sham injection group also achieved this primary outcome, which is compatible with another trial that used saline injection as control. The placebo effect cannot be negated as the sham group experienced improvement up to six months. The mechanism of action is obscure.

There remains a shortage of well‐designed randomised trials to evaluate the efficacy of perianal injection of bulking agents, and the studies reviewed failed to answer other important questions surrounding this treatment. There are wide variations in the agents and techniques used (submucosal versus intersphincteric, use of transanal ultrasound). Safety and potential complications have not been thoroughly assessed and the quality of reports has generally been poor. This needs further, more rigorous evaluation with longer term follow up for potential adverse events. The selection criteria for patients and the primary outcome measure, thus the definition of successful treatment, have been variable. These important questions surrounding this treatment need to be addressed in a well‐designed RCT with adequate power to assess the outcomes.

There appears to be a gap between patients' subjective evaluation of their symptoms and the incontinence scores, particularly in observational studies. Regardless of the outcome of the scores the trials in this review all showed improvement in a faecal incontinence quality of life scale, and thus this discrepancy needs to be addressed in future research.

Summary of main results

One large randomised trial has shown that dextranomer stabilised in hyaluronic acid (NASHA Dx) is efficacious to treat faecal incontinence (Graf 2011). The injection was effective up to 12 months.

Several of the studies showed that there were short term improvements in faecal incontinence after injections of a variety of materials or with injection techniques. Some materials were better than others, at least in the short term, as silicone material was better than the carbon‐coated beads (Tjandra 2009). Similarly, ultrasound‐guided injections seemed to have short term benefits over digital guidance (Tjandra 2004).

Two trials comparing active treatment against sham injection showed an improvement of symptoms in up to 27% of the control treatment group, thus the possibility of placebo effect should be noted.

Complications are common but mostly appear to be relatively minor and of short duration, resolving spontaneously in most cases. There has been no long term follow up of RCT results published to date.

Overall completeness and applicability of evidence

The number of studies available to address the objectives of this review was limited.

There is a lack of information regarding the volume, the precise location where the agent should be placed, and the choice of guidance of the needle track.

Quality of the evidence

Only two of the studies provided enough data to reliably assess the chance of bias, and most of the studies were small with short duration of follow up. Some studies did not supply data in a form suitable for analysis.

Potential biases in the review process

The number of references identified was small. The limitations of this review are the variable outcome measures used in eligible trials and that meta‐analysis was not possible.

Agreements and disagreements with other studies or reviews

Similar reviews which included case‐series (Hussain 2011; Luo 2010) reached the same conclusion that evidence on the efficacy of this treatment is weak and most studies conducted for this treatment have been of poor quality.

PRISMA study flow diagram,
Figuras y tablas -
Figure 1

PRISMA study flow diagram,

Methodological quality graph: review authors' judgements about each methodological quality item presented as percentages across all included studies.
Figuras y tablas -
Figure 2

Methodological quality graph: review authors' judgements about each methodological quality item presented as percentages across all included studies.

Methodological quality summary: review authors' judgements about each methodological quality item for each included study.
Figuras y tablas -
Figure 3

Methodological quality summary: review authors' judgements about each methodological quality item for each included study.

Comparison 1 Injectable versus placebo injection, Outcome 1 Failure (number of participants with Wexner's >8).
Figuras y tablas -
Analysis 1.1

Comparison 1 Injectable versus placebo injection, Outcome 1 Failure (number of participants with Wexner's >8).

Comparison 1 Injectable versus placebo injection, Outcome 2 No improvement (less than 50% reduction in incontinence episodes.
Figuras y tablas -
Analysis 1.2

Comparison 1 Injectable versus placebo injection, Outcome 2 No improvement (less than 50% reduction in incontinence episodes.

Comparison 1 Injectable versus placebo injection, Outcome 3 Number of participants wearing pads every day.
Figuras y tablas -
Analysis 1.3

Comparison 1 Injectable versus placebo injection, Outcome 3 Number of participants wearing pads every day.

Comparison 1 Injectable versus placebo injection, Outcome 4 Number of incontinence free days at 6 months.
Figuras y tablas -
Analysis 1.4

Comparison 1 Injectable versus placebo injection, Outcome 4 Number of incontinence free days at 6 months.

Comparison 1 Injectable versus placebo injection, Outcome 5 Wexner score (mean).
Figuras y tablas -
Analysis 1.5

Comparison 1 Injectable versus placebo injection, Outcome 5 Wexner score (mean).

Comparison 1 Injectable versus placebo injection, Outcome 6 Number of adverse effects.
Figuras y tablas -
Analysis 1.6

Comparison 1 Injectable versus placebo injection, Outcome 6 Number of adverse effects.

Comparison 1 Injectable versus placebo injection, Outcome 7 Serious adverse effects.
Figuras y tablas -
Analysis 1.7

Comparison 1 Injectable versus placebo injection, Outcome 7 Serious adverse effects.

Comparison 1 Injectable versus placebo injection, Outcome 8 Need for re‐treatment at 6 months.
Figuras y tablas -
Analysis 1.8

Comparison 1 Injectable versus placebo injection, Outcome 8 Need for re‐treatment at 6 months.

Comparison 2 One injectable material versus another, Outcome 1 Failure (number with worse faecal incontinence).
Figuras y tablas -
Analysis 2.1

Comparison 2 One injectable material versus another, Outcome 1 Failure (number with worse faecal incontinence).

Comparison 2 One injectable material versus another, Outcome 2 Wexner's incontinence score.
Figuras y tablas -
Analysis 2.2

Comparison 2 One injectable material versus another, Outcome 2 Wexner's incontinence score.

Comparison 2 One injectable material versus another, Outcome 3 Quality of life index (lifestyle) at 6 months.
Figuras y tablas -
Analysis 2.3

Comparison 2 One injectable material versus another, Outcome 3 Quality of life index (lifestyle) at 6 months.

Comparison 2 One injectable material versus another, Outcome 4 Adverse effects.
Figuras y tablas -
Analysis 2.4

Comparison 2 One injectable material versus another, Outcome 4 Adverse effects.

Comparison 2 One injectable material versus another, Outcome 5 Serious adverse effects.
Figuras y tablas -
Analysis 2.5

Comparison 2 One injectable material versus another, Outcome 5 Serious adverse effects.

Comparison 3 One method of injection versus another, Outcome 1 Failure (number of participants with Wexner's score <50% improved).
Figuras y tablas -
Analysis 3.1

Comparison 3 One method of injection versus another, Outcome 1 Failure (number of participants with Wexner's score <50% improved).

Comparison 3 One method of injection versus another, Outcome 2 Failure (number of participants global Quality of Life score <50% improved).
Figuras y tablas -
Analysis 3.2

Comparison 3 One method of injection versus another, Outcome 2 Failure (number of participants global Quality of Life score <50% improved).

Comparison 3 One method of injection versus another, Outcome 3 Quality of life index (lifestyle) at 6 months.
Figuras y tablas -
Analysis 3.3

Comparison 3 One method of injection versus another, Outcome 3 Quality of life index (lifestyle) at 6 months.

Comparison 3 One method of injection versus another, Outcome 4 Discomfort at injection site.
Figuras y tablas -
Analysis 3.4

Comparison 3 One method of injection versus another, Outcome 4 Discomfort at injection site.

Comparison 3 One method of injection versus another, Outcome 5 Adverse effects.
Figuras y tablas -
Analysis 3.5

Comparison 3 One method of injection versus another, Outcome 5 Adverse effects.

Table 1. Summary of complications

Agent

Authors and Year

No of patients

Injection route

Total volume

Complications

Number of adverse effects/Number of participants

Autologous fat

Shafik 1995

14

Submucosal

15‐20ml

Reports that there were no complications

0/14

Bernardi 1998

1

Perianal

130ml

Reports that there were no complications

0/1

Bioplastique™/PTQ™

Malouf 2001

10

Perianal

5‐11.5ml

4 anal canal ulcer, 1 injection site pain, 1 leakage of injected material

6/10

Tjandra 2004

82

Perianal

10.0ml

6 minor discomfort at injection site (4: digital guidance group, 2: ultrasound guidance group)

6/82

Chan 2006

7

Perianal

Not mentioned

Reports that there were no complications

0/7

de la Portilla 2007

20

Perianal

7.5ml

Not reported

Not reported

Maeda 2007

6

Perianal

7.5ml

1 recto‐vaginal fistula

1/6

van der Hagen 2007

24

Perianal

7.5ml

Not reported

Not reported

Gett 2007

37

Not mentioned

Not mentioned

4 perianal abscess required surgical drainage

4/37

Siproudhis 2007

22

Perianal

7.5ml

6 pain at the implant site, 2 anal inflammation

8/22

Soerensen 2009

33

Perianal

7.5ml

Reports that there were no complications

0/33

Tjandra 2009

20

Perianal

10.0ml

4 bruising

4/20

Bartlett 2009

74

Perianal

10.0ml

9 minor complications

9/74

van Wunnik 2012

50

Perianal

Not mentioned

2 local giant cell foreign body reaction

2/50

Bulkamid™

Maeda 2008

5

Perianal

median 9ml (8‐9)

Reports that there were no complications

0/5

Coaptite®

Ganio 2008

10

Perianal

4ml

1 leakage of Coaptite®

1/10

Contigen®

Kumar 1998

17

Submucosal

2ml

Reports that there were no complications

0/17

Stojkovic 2006

73

Submucosal

5ml

Not reported

Not reported

Durasphere®/ACYST‐TM

Weiss 2002

7

Submucosal

average 6.8ml

Not reported

Not reported

Davis 2003

18

Submucosal

mean 1.28ml at 1‐4 sites

2 anal discomfort, 1 exacerbation of pruritis ani, 2 passage of injected Durasphere via anus

5/18

Altomare 2008

33

Submucosal

median 8.8ml (2‐19ml)

2 anal pain, 1 Durasphere® leakage, 2 material migration

5/33

Aigner 2009

11

Perianal

mean 9ml (8‐12ml)

Local pain (most frequent, no numbers reported), 3 passage of Durasphere®

At least 3/11

Tjandra 2009

20

Submucosal

10.0ml

4 bruising, 2 erosion of rectal mucosa, 1 rectal pain, 1 type III hypersensitivity

8/20

Gatekeeper™ (polyacrylonitrile)

Ratto 2011

14

Perianal

1 cylinder (length 21mm, diameter 1‐2mm)x4

Reports that there were none.

0/14

NASHA™Dx

Dehli 2007

4

Submucosal

5.6ml

1 bleeding settled with compression, 1 anal pain, 1 tenesmus. All complications settled within 2‐7 days after procedure.

3/4

Danielson 2009

34

Submucosal

4ml

Pain (26% during 1st injection procedure, 55% for second treatment), 3 suspected inflammation of anal canal, 2 sensation of obstructed defaecation

At least 5/34

Graf 2011

136

Submucosal

4‐8ml

128 adverse events in total. Two serious events, one prostatic abscess and one rectal abscess.

128/136

Dodi 2010

115

Submucosal

up to 4ml

154 adverse events, including 20 serious events such as abscess and haemorrhage

154 adverse events by 70 patients

Permacol™

Smart 2005

7

Submucosal

Not mentioned

Reports that there were no complications

0/7

Maeda 2008

5

Perianal

median 15ml (15‐17.5)

Reports that there were no complications

0/5

Saline

Siproudhis 2007

22

Perianal

7.5ml

2 pain at the implant site

2/22

Synthetic collagen

Ullah 2011

11

Submucosal

Not specified

One death unrelated to the treatment

1/11

Teflon®

Shafik 1993

11

Submucosal

10ml

Not reported

Not reported

Urosurge®

Feretis 2001

6

Submucosal

up to 5 balloons

1 bleeding, 1 lost balloon after 2 months (potential spontaneous burst)

2/6

Bioplastique™/PTQ™: Silicone biomaterial

Bulkamid™: Hydrogel cross‐linked with polyacrylamide

Coaptite®: Calcium hydroxylapatite

Contigen®: Synthetic bovine collagen

Durasphere®/ACYST‐TM: Carbon‐coated microbeads

NASHA™Dx: Stabilized nonanimal hyaluronic acid with dextranomer

Permacol™: Porcine dermal collagen

Teflon®: Polytetrafluoroethylene

Urosurge®: Expandable silicone microballoon

Figuras y tablas -
Table 1. Summary of complications
Comparison 1. Injectable versus placebo injection

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Failure (number of participants with Wexner's >8) Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

1.1 Silicone material (PTQ) versus saline

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

2 No improvement (less than 50% reduction in incontinence episodes Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

2.1 Dextranomer stabilised in hyaluronic acid (NASHA Dx) versus sham injection

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

3 Number of participants wearing pads every day Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

3.1 Silicone material (PTQ) versus saline

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

4 Number of incontinence free days at 6 months Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Totals not selected

4.1 Dextranomer stabilised in hyaluronic acid (NASHA Dx) versus sham injection

1

Mean Difference (IV, Fixed, 95% CI)

0.0 [0.0, 0.0]

5 Wexner score (mean) Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Totals not selected

5.1 Silicone material (PTQ) versus saline

1

Mean Difference (IV, Fixed, 95% CI)

0.0 [0.0, 0.0]

6 Number of adverse effects Show forest plot

2

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

6.1 Silicone biomaterial (PTQ) versus saline injection

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

6.2 Dextranomer stabilised in hyaluronic acid (NASHA Dx) versus sham injection

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

7 Serious adverse effects Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

7.1 Dextranomer stabilised in hyaluronic acid (NASHA Dx) versus sham injection

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

8 Need for re‐treatment at 6 months Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

8.1 Dextranomer stabilised in hyaluronic acid (NASHA Dx) versus sham injection

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

Figuras y tablas -
Comparison 1. Injectable versus placebo injection
Comparison 2. One injectable material versus another

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Failure (number with worse faecal incontinence) Show forest plot

2

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

1.1 hydrogel crosslinked with polyacrylamide versus porcine dermal collagen

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

1.2 silicone biomaterial (PTQ) versus carbon‐coated spheres (Durasphere) at 6 months

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

1.3 silicone biomaterial (PTQ) versus carbon‐coated spheres (Durasphere) at 12 months

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

2 Wexner's incontinence score Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Totals not selected

2.1 silicone biomaterial (PTQ) versus carbon‐coated spheres (Durasphere) at 6 months

1

Mean Difference (IV, Fixed, 95% CI)

0.0 [0.0, 0.0]

2.2 silicone biomaterial (PTQ) versus carbon‐coated spheres (Durasphere) at12 months

1

Mean Difference (IV, Fixed, 95% CI)

0.0 [0.0, 0.0]

3 Quality of life index (lifestyle) at 6 months Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Totals not selected

3.1 silicone biomaterial (PTQ) versus carbon‐coated spheres (Durasphere) at 6 months

1

Mean Difference (IV, Fixed, 95% CI)

0.0 [0.0, 0.0]

3.2 silicone biomaterial (PTQ) versus carbon‐coated spheres (Durasphere) at 12 months

1

Mean Difference (IV, Fixed, 95% CI)

0.0 [0.0, 0.0]

4 Adverse effects Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

4.1 silicone biomaterial (PTQ) versus carbon‐coated spheres (Durasphere)

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

5 Serious adverse effects Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

5.1 silicone biomaterial (PTQ) versus carbon‐coated spheres (Durasphere)

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

Figuras y tablas -
Comparison 2. One injectable material versus another
Comparison 3. One method of injection versus another

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Failure (number of participants with Wexner's score <50% improved) Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

1.1 Endoanal ultrasound guidance versus digital guidance

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

2 Failure (number of participants global Quality of Life score <50% improved) Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

2.1 Endoanal ultrasound guidance versus digital guidance

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

3 Quality of life index (lifestyle) at 6 months Show forest plot

1

Mean Difference (IV, Fixed, 95% CI)

Totals not selected

3.1 Endoanal ultrasound guidance versus digital guidance

1

Mean Difference (IV, Fixed, 95% CI)

0.0 [0.0, 0.0]

4 Discomfort at injection site Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

4.1 Endoanal ultrasound guidance versus digital guidance

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

5 Adverse effects Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

5.1 Endoanal ultrasound guidance versus digital guidance

1

Risk Ratio (M‐H, Fixed, 95% CI)

0.0 [0.0, 0.0]

Figuras y tablas -
Comparison 3. One method of injection versus another