Background The use of 5-aminosalicylates (5-ASAs) in Crohn's disease (CD) is controversial. A recent Cochrane review found that 5-ASAs are not effective for the maintenance of medically-induced remission in CD but their role in the maintenance of surgically-induced remission is unclear.

Aim To evaluate articles that investigated the use of 5-ASAs for prevention of postoperative relapses in CD.

Design Systematic review and meta-analyses of randomised controlled trials (RCTs) published between 1966 and October 2009.

Methods Data sources were MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Inflammatory Bowel Disease Specialised Register and reference lists of retrieved articles. The authors included trials which compared oral 5-ASAs with either placebo or other interventions. Data extraction and assessment of methodological quality were performed independently by two reviewers.

Results Ten RCTs met the inclusion criteria. Meta-analysis of the results of 8 placebo-controlled trials involving 1061 participants showed that the risk of postoperative clinical relapses was significantly reduced in patients who received oral 5-ASA compared with those who received placebo (pooled odds ratio 0.68, 95% CI 0.52 to 0.90). The incidence of adverse events was not statistically significantly different between the 5-ASA and placebo groups (pooled odds ratio 1.02, 95% CI 0.60 to 1.76). In two other studies in which oral 5-ASAs were compared with azathioprine, no statistically significant difference in clinical relapses was found but the sample sizes of these studies were small.

Conclusion Oral 5-ASAs are superior to placebo for the prevention of postoperative relapses in Crohn's disease. The authors recommend the use of 5-ASAs as maintenance therapy following surgically-induced remission in CD as they appear effective and are not associated with significant adverse events.