The prevalence of hidradenitis suppurativa in 1093 patients with inflammatory bowel disease

Funding sources: none. Conflicts of interest: none declared. Dear Editor, Hidradenitis suppurativa (HS), also known as acne inversa, is an inflammatory skin disease characterized by painful nodules, abscesses and fistulas.1 The groin, axillae and buttocks are the most frequently affected skin areas.2 Disease‐associated factors include smoking, obesity, mechanical friction, genetic predisposition, hormonal influences and an aberrant innate immune response.1 The main treatment options include systemic antibiotics, such as clindamycin with rifampicin, surgery, and in severe cases antitumour necrosis factor‐α biologics.3 HS has a reported prevalence of up to 4%, although it was recently estimated at six per 100 000 in the U.S.A.4 Inflammatory bowel disease (IBD) is an umbrella term that includes Crohn disease (CD) and ulcerative colitis (UC). The prevalence rates of adult CD and UC in the U.S.A. are 0·201% and 0·238%, respectively.5 HS has been reported to co‐occur with CD, with several case reports suggesting an association.6 Recently, we estimated the prevalence of HS at 16% in a cohort of 158 patients with IBD, and we provided a comparison between HS and IBD.6 We also suggested that an association might demonstrate a similar pathogenic mechanism providing new therapeutic options for HS.6 In this sequel study, we present the self‐reported prevalence of HS and its disease characteristics in a large cohort of patients with IBD.