Efficacy of immunosuppressive therapy for inflammatory bowel disease: a systematic review and meta-analysis.

Objectives: There remains controversy regarding the efficacy of thiopurine analogs (azathioprine (AZA) and 6-mercaptopurine (6-MP)), methotrexate (MTX), and cyclosporine for the treatment of inflammatory bowel disease (IBD). We performed an updated systematic review of the literature to clarify the efficacy of immunosuppressive therapy at inducing remission and preventing relapse in ulcerative colitis (UC) and Crohn's disease (CD).

Methods: Only parallel group randomized controlled trials (RCTs) were considered eligible. Studies with adult IBD patients receiving immunosuppressive therapy compared with placebo for at least 14 days and up to 17 weeks for active disease, or at least 6 months in quiescent disease were analyzed. Two reviewers independently assessed eligibility and extracted data. The primary outcome was remission or relapse using an intention-to-treat analysis. The data were summarized using relative risk (RR) and pooled using a random effects model.

Results: Data on MTX and cyclosporine in IBD were limited although there were some data to support the use of intramuscular MTX in CD but not UC. There were five trials of AZA/6-MP in 380 active CD patients and there was no significant effect of therapy inducing remission (RR=0.87; 95% confidence interval (CI)=0.71-1.06). In quiescent CD, there were two trials involving 198 patients with no significant benefit of active therapy preventing relapse compared with placebo (RR=0.64; 95% CI=0.34-1.23). There were, however, three additional AZA withdrawal trials in 163 patients that indicated continuing medication did prevent relapse (RR=0.39; 95% CI=0.21-0.74). There were two AZA RCTs in 130 active UC patients that suggested a trend for benefit of therapy, but this did not reach statistical significance (RR=0.85; 95% CI=0.71-1.01). In quiescent UC, there were three trials involving 127 patients and there was a statistically significant benefit of AZA preventing relapse (RR=0.60; 95% CI=0.37-0.95).

Conclusions: Most evidence relates to AZA/6-MP where there is no statistically significant benefit at inducing remission in active CD and UC. Thiopurine analogs may prevent relapse in quiescent UC and CD. However, there is a paucity of data for immunosuppressive therapy in IBD and more research is needed.