Supplementary Material for: Factors associated with severe hidradenitis suppurativa, using Hurley staging and Metascore

Introduction. Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease for which certain risk factors are well known: obesity and smoking (in particular). However, the factors associated with more severe conditions, and therefore potential aggravators of the disease, remain a matter of debate.
Our study aims to determine the clinical factors associated with severe HS using several severity scores.
Methods. The data were obtained via the ERHS questionnaire from patients exclusively recruited at Erasme Hospital in Brussels. The severity of HS was firstly estimated by the Hurley score, and secondly by a metascore, a system combining the iHS4, HS-PGA, SAHS and DLQI. Univariable and multivariable analyses were performed.
Results. Six hundred and forty-seven patients were included in the Hurley analysis, and 456 patients in the metascore analysis. In multivariable analysis, men have a more severe metascore than women (OR = 1.89, p = 0.022), smoking was associated with a more severe disease according to metascore, especially in mild cases (OR = 0.76, p = 0.043), and an elevated BMI was associated with having Hurley stage III disease compared to Hurley I or II disease (OR = 1.09, p = 0.001). A significant association is also shown between blood pressure and Hurley stage (OR = 0.97, p = 0.025). Self-reports of NSAIDs aggravating the disease is also a factor associated with greater severity according to the metascore (OR = 0.12, p = 0.008). Finally, several locations of HS lesions were associated with greater severity, in particular the armpits according to the metascore (OR = 0.29, p < 0.001), and the perianal area according to the Hurley score (OR = 0.15, p < 0.001).
Conclusion. HS seems to be more severe in men, smoking seems to aggravate mild cases of HS, while increased body mass index plays a major role in the transition from Hurley II to Hurley III.