Prevalence of inflammatory bowel disease (IBD) in hidradenitis suppurativa (HS): systematic review and adjusted meta-analysis.

Background: Several case reports and case series have recently explored the association between hidradenitis suppurativa (HS) and inflammatory bowel disease (IBD).

Objective: We performed a systematic review and meta-analysis of case-control studies to determine  (i) the pooled prevalence of IBD in HS cohorts, and (ii) whether HS is more strongly associated with Crohn's disease or ulcerative colitis.

Methods: Electronic searches were performed using five databases, from their inception to August 2018. Case-control studies reporting the proportion of IBD cases in HS cohorts were included and meta-analysis performed.

Results: From six included studies, a significant association between HS and IBD after pooling of adjusted effect sizes was identified (OR 2.12; 95% CI 1.62-2.77; P = 0.03). Subgroup analysis demonstrated a significant association between HS and Crohn's disease (OR 2.25; 95% CI 1.52-3.32; P < 0.0001, I = 92%) and with ulcerative colitis (OR 1.56; 95% CI 1.26-1.94; P < 0.0001; I = 36%).

Limitations: Studies reviewed were observational by design which are susceptible to bias and lack of randomization.

Conclusions: Our results indicate a statistically significant association between HS and IBD. Our results highlight that all patients with HS should be clinically screened for symptoms of IBD and symptomatic patients referred for further investigations.