Hidradenitis suppurativa: Evaluating activity patterns and predictors of recalcitrant course-A population-based study

Background Epidemiological evidence regarding the course and activity patterns of hidradenitis suppurativa (HS) is yet to be delineated. Objective To identify activity patterns of HS throughout the time axis and to outline predictors of recalcitrant disease course. Methods A population-based retrospective cohort study was performed to follow patients with HS (n = 4417) throughout the initial 10 years following their diagnosis. The disease was considered active in a certain month if one of the following criteria was fulfilled: (i) purchase of an HS-related drug, (ii) admission to a dermatological ward and (iii) referral to a dermatological consultation in an emergency room. Patients with a recalcitrant disease were defined as those with >= 5 years of follow-up with >= 6 'active months' each. Patients with an indolent course were defined as those experiencing >= 9 years of follow-up with <= 1 'active months' each. Results The average (SD) number of months in which patients had an active disease was 1.37 (1.28) months per year. While 98 (2.2%) patients pursued a recalcitrant course, 1390 (31.5%) went through an indolent disease course. Older age (>= 38 years; adjusted OR, 6.17; 95% CI, 3.33-11.43), Arab ethnicity (adjusted OR, 2.04; 95% CI, 1.20-3.48), low socioeconomic status (adjusted OR, 1.64; 95% CI, 1.03-2.60), obesity (adjusted OR, 3.47; 95% CI, 2.25-5.34) and smoking (adjusted OR, 2.65; 95% CI, 1.57-4.47) were found to independently predict recalcitrant course of HS. Conclusions Mild course is more frequently encountered than severe course among Israeli patients with HS. Modifiable risk factors of recalcitrant course should be carefully addressed.