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-2 = 92%) and with ulcerative colitis (OR 1.56; 95% CI 1.26-1.94; P I-2 = 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.