Effect of cannabinoids in mild-to-moderate cases of Crohn's disease as compared to placebo: a systematic review and meta-analysis of randomised controlled trials.

Introduction: In view of limited treatment options (those too may fail) for Crohn's disease, cannabinoids have been tried as a therapeutic. However, their efficacy is not unequivocally established. This systematic review and meta-analysis was planned to pool data from randomised controlled trials (RCTs) evaluating effect of cannabinoids in Crohn's disease with an intention to take this uncertainty away.

Content: Following literature search in Medline, EMBASE, Scopus and Google Scholar databases, RCTs assessing the effect of cannabinoids on mild-to-moderate Crohn's disease in adults were included. Crohns' disease activity index (CDAI), QoL (Quality of life), number participants achieving full remission and serum CRP at eight weeks of treatment were the outcomes considered for meta-analysis. Quality of studies was assessed using Cochrane's RoB2 tool. Random effect model was applied for meta-analysis. Heterogeneity was assessed by Cochrane 'Q' statistics and I² test. Sensitivity analysis was performed to identify the major contributor(s) to heterogeneity and assess robustness of the results.

Summary: Risk of bias for the four included studies varied from 'low' to 'some concern'. Overall effect estimate (SMD -0.92; 95 % CI -1.80, -0.03) indicated a statistically significant effect of cannabinoids as compared to control (p<0.05) on CDAI score. Effect of cannabinoids on rest of the outcome parameters was comparable to that of placebo. Magnitude of heterogeneity for different outcome parameters ranged from 'low' to 'substantial'.

Outlook: Cannabinoids were superior to placebo for favourably affecting the disease severity in terms of CDAI score. However, no statistically significant difference was found between the two for improving QoL, causing full disease-remission and reducing inflammatory markers. The results must be interpreted with caution in view of relatively high heterogeneity among the studies.