A Systematic Review With Meta-Analysis of the Efficacy of Cannabis and Cannabinoids for Inflammatory Bowel Disease: What Can We Learn From Randomized and Nonrandomized Studies?

Goal and background: A number of studies have investigated the effectiveness of cannabis or cannabinoids for treatment of inflammatory bowel diseases (IBD). We aimed to systematically analyze their effect in in the treatment of IBD patients.

Study: We included randomized controlled trials and nonrandomized studies analyzing IBD patients of any age using cannabi(noid)s. Two reviewers searched 3 databases until August 13, 2019. Primary outcome was clinical remission and secondary outcomes included inflammatory biomarkers, symptom improvement, quality of life (QoL) scores, and hospital outcomes. Risk of bias was assessed according to study type. The meta-analyses were performed using a random-effects model with subgroup analyses based on study type.

Results: The search identified 682 records of which 15 nonrandomized studies and 5 randomized controlled trials were eligible for inclusion. The meta-analysis of the primary outcome included 146 randomized participants, all 18 years of age or older. Risk of bias was moderate. Cannabi(noid)s were not effective at inducing remission (risk ratio=1.56, 95% confidence interval=0.99-2.46). No effect on inflammatory biomarkers was observed. However, clinical symptoms (abdominal pain, general well-being, nausea, diarrhea, and poor appetite) all improved with cannabi(noid)s on Likert-scales. Baseline QoL scores were lower in patients using cannabis among cohort studies but improved significantly with cannabi(noid)s. Although length of hospital stay was shorter and risk of parenteral nutrition was lower in patients using cannabis, there was no effect on other IBD complications.

Conclusions: Cannabi(noid)s do not induce clinical remission or affect inflammation in IBD patients. However, cannabi(noid)s significantly improve patient-reported symptoms and QoL.