This review assessed the function and complications of a colonic J-pouch compared with straight coloanal anastomosis. The authors concluded that there was little difference between the two interventions, but data appeared to favour the use of colonic J-pouches. Given some methodological limitations and insufficient reporting of study details, the reliability of this conclusion is unclear.

To compare the function and complications of a straight coloanal anastomosis with a colonic J-pouch one year post-operatively in patients with rectal excision.

MEDLINE, PubMed and the Cochrane Controlled Trials Register were searched from 1980 to 2005; the search terms were reported. Only papers written in English were eligible for inclusion. Reference lists of short-listed articles, and relevant journals and conference proceedings (unspecified), were also searched.

Study designs of evaluations included in the review

Randomised controlled trials (RCTs) where patients were followed up at one year were eligible for inclusion.

Specific interventions included in the review

Studies comparing colonic J-pouch of less than 10 cm with straight coloanal anastomosis were eligible for inclusion. The descending colon and the sigmoid colon were used for pouch formation in the included studies.

Participants included in the review

Studies of patients with either colonic J-pouch or straight coloanal anastomosis after a curative low anterior resection for mid and low rectal cancers were eligible for inclusion. Patients who experienced faecal incontinence pre-operatively were excluded.

Outcomes assessed in the review

The outcomes of interest were stool frequency, faecal continence, anastomotic leak rate and stricture formation. The included studies used different methods to measure these outcomes.

How were decisions on the relevance of primary studies made?

Titles and abstracts of articles identified by the search were screened, copies of potentially relevant abstracts were obtained and articles were retrieved if the inclusion criteria appeared to be met. Two reviewers independently performed this process. Any disagreements were resolved through discussion.

The quality of the studies was assessed using the Consolidated Standards of Reporting Trials (CONSORT) checklist. The reviewers also assessed the studies against further criteria, such as adequate sample sizes, details of adverse events, and clear definition of the size and construction of colonic J-pouches. Two reviewers independently performed the validity assessment. Titles and abstracts of articles identified by the search were screened, copies of potentially relevant abstracts were obtained, and articles were retrieved if the inclusion criteria appeared to be met. Two reviewers independently performed this process. Any disagreements were resolved through discussion.

The primary reviewer extracted and entered the data, which a second reviewer then checked. For dichotomous variables, data on the numbers of events in each group were used to calculate the odds ratio (OR) or relative risk (RR) with 95% confidence intervals (CIs). For stool frequency, data on the mean value and standard deviation in each group were used to calculate the weighted mean difference (WMD) and its 95% CI.

How were the studies combined?

The results from the studies were combined by meta-analysis using a fixed-effect model.

How were differences between studies investigated?

Statistical heterogeneity was assessed using the chi-squared test and I-squared statistic.

Eight RCTs (n=391) were included.

Only one study reported an a priori sample size calculation. Methods of randomisation with allocation concealment were reported in six of the included studies and one study had blinded assessors. Seven of the included studies clearly reported on pouch formation. One study did not use intention-to-treat principles.

Anastomotic leak.

Straight coloanal anastomosis was associated with a non significant increased risk of anastomotic leak compared with colonic J-pouch (RR 0.36, 95% CI: 0.12, 1.08). Four of the six studies measuring anastomotic leak rate found no incidence in either group and were not weighted in the analysis.

Anastomotic stricture.

Colonic J-pouch was associated with a non significant increased risk of anastomotic stricture compared with straight coloanal anastomosis (RR 2.45, 95% CI: 0.79, 7.57). Only two studies measured anastomotic stricture. There was no evidence of heterogeneity (I-squared 0%).

Faecal incontinence.

Straight coloanal anastomosis was associated with a statistically significant increase in odds of experiencing faecal incontinence compared with colonic J-pouch (OR 0.23, 95% CI: 0.08, 0.68).

Stool frequency.

There was a statistically significant but non clinically significant difference in stool frequency favouring the J-pouch (WMD -1.21, 95% CI: -1.92, -0.49) in the two studies included in the analysis. There was evidence of considerable and statistically significant heterogeneity (I-squared 81.3%).

No

One year post-operatively, colonic J-pouches and straight coloanal anastomosis showed minimal differences in functional outcomes. However, the limited data appear to favour a J-pouch reconstruction.

Inclusion criteria for the participants, study design and intervention were clearly stated. A range of sources were searched. However, restricting the review to articles in English means that relevant studies might have been missed. It was unclear whether attempts were made to identify unpublished studies and publication bias was not assessed. Validity was assessed, but the method used was not described clearly and appeared to involve, in part, the use of a checklist designed to assess the quality of reporting rather than study validity. Appropriate steps were taken in the validity assessment and selection of studies to minimise error and bias. In addition, one reviewer extracted the data and another checked the extraction, which provides a degree of protection against error and bias.

There was insufficient detail about the quality and characteristics of the included studies to draw firm conclusions about internal or external validity. The outcome measures varied between studies, statistical heterogeneity was found for some outcomes, and some outcomes were only reported in one or two studies. This suggests that the decision to combine the studies in a meta-analysis was not appropriate. The small sample sizes and number of studies included for some outcomes also limit the potential to draw meaningful conclusions. Given these limitations, it is unclear how reliable the authors' conclusions are.

Practice: The authors did not state any implications for practice.

Research: The authors stated that further large, prospective randomised studies with standardised and validated functional outcome measures, as well as standardised parameters for the reporting of pouch formation, are required.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.