The prevalence of inflammatory bowel disease in patients with hidradenitis suppurativa

Background: Hidradenitis suppurativa is a chronic inflammatory skin disease associated with many other systemic manifestations including metabolic syndrome. Multiple other inflammatory disorders have been associated with inflammatory bowel disease including psoriasis and rosacea. IBD has been reported with HS however analysis have often utilized large data pulls which rely on International Classification of Diseases (ICD) coding. This leads to the possibility of overestimating prevalence. Objective: To investigate a possible association between hidradenitis suppurativa and inflammatory bowel disease using data pull analysis from ICD-9 and -10 codes and data verification by complete chart review. Methods: A retrospective chart review of all dermatology clinic encounters from January 1, 2005, to May 31, 2016, identified 983 subjects with an appropriate diagnosis of hidradenitis suppurativa. These patients were cross-matched with the diagnosis of inflammatory bowel disease, including Crohn’s disease and inflammatory bowel disease. We compared the incidence with an age, sex and race matched control population. Results: ICD coding identified 56 patients as having both IBD and HS out of 983 HS patients. After chart review, 20 cases were verified. The false positive rate was 3.7%. The prevalence of inflammatory bowel disease in hidradenitis suppurativa patients was 2.0%. In the control group, 15 of 983 patients were identified as having IBD yet none had IBD after chart verification. This was a false positive rate of 1.5%, and the prevalence of IBD in the controls was 0. There is a significantly increased risk for IBD in patients with HS compared with controls, 2.0% vs. 0 ( P = .001). Limitations: This was a retrospective review. Conclusion: Our results indicate that hidradenitis suppurativa patients may be at high risk for inflammatory bowel disease. The use of ICD coding can overestimate the prevalence