Evidence supporting the benefits of marijuana for Crohn's disease and ulcerative colitis is extremely limited: a meta-analysis of the literature.

Background Medical marijuana is increasingly used to control inflammation and pain in inflammatory bowel disease (IBD). We performed a meta-analysis to investigate the effect of marijuana on the clinical response, induction of clinical remission, and maintenance of clinical remission compared to placebo/standard of care. Methods We performed a systematic search of PubMed, Embase, and Web of Science in June 2019, for cannabis/marijuana and IBD, Crohn's disease or ulcerative colitis (UC). The statistical analysis was performed using Revman (version 5.3). GRADE methodology was used to assess the quality of the evidence. Results Of the 334 studies initially reviewed, 1 trial in UC and 2 trials in Crohn's disease met eligibility. For UC, 29 patients were treated with marijuana and 31 with placebo/standard of care. There was no difference in failure to achieve clinical remission (relative risk [RR] 1.02, 95% confidence interval [CI] 0.76-1.37) or response (RR 0.99, 95%CI 0.65-1.21). Adverse events occurred in all patients receiving marijuana (RR 1.28, 95%CI 1.05-1.56). For Crohn's disease, 21 patients were treated with marijuana and 19 with placebo/standard of care. There was no difference in failure to achieve clinical remission (RR 0.72, 95%CI 0.47-1.12) or failure to achieve clinical response (RR 0.15, 95%CI 0.02-1.05). Adverse events were not reported per patient. The quality of evidence was low to very low using GRADE methodology. Conclusions Data supporting the use of marijuana for the management of IBD are extremely limited. Further well-designed studies are needed before any positive conclusions regarding marijuana use can be drawn.