Background: Accumulating evidence suggests that hyperbaric oxygen therapy (HBOT) may be effective for inflammatory bowel disease (IBD). Our systematic review aimed to quantify the effectiveness and safety of HBOT in various IBD phenotypes.

Methods: We performed a proportional meta-analysis. Multiple databases were systematically searched from inception through November 2020 without language restriction. We included studies that reported effectiveness and/or safety of HBOT in IBD. Weighted summary estimates with 95% confidence intervals (Cis) were calculated for clinical outcomes for each IBD phenotype using random-effects models. Study quality was assessed using the Cochrane evaluation handbook and National Institute of Health criteria.

Results: Nineteen studies with 809 patients total were eligible: 3 randomized controlled trials and 16 case series. Rates of clinical remission included 87% (95% CI, 10-100) for ulcerative colitis (n = 42), 88% (95% CI, 46-98) for luminal Crohn's disease (CD, n = 8), 60% (95% CI, 40-76) for perianal CD (n = 102), 31% (95% CI, 16-50) for pouch disorders (n = 60), 92% (95% CI, 38-100) for pyoderma gangrenosum (n = 5), and 65% (95% CI, 10-97) for perianal sinus/metastatic CD (n = 7). Of the 12 studies that reported on safety, 15% of patients (n = 30) had minor adverse events. Study quality was low in the majority of studies due to an absence of comparator arms, inadequate description of concomitant interventions, and/or lack of objective outcomes.

Conclusions: Limited high-quality evidence suggests that HBOT is safe and associated with substantial rates of clinical remission for multiple IBD phenotypes. Well-designed randomized controlled trials are warranted to confirm the benefit of HBOT in IBD.