Trends in body mass index before and after diagnosis of hidradenitis suppurativa.

Abstract

A temporal relationship between hidradenitis suppurativa (HS) and obesity has not been established. To compare baseline body mass index (BMI) and change in BMI for patients with HS and controls before and after diagnosis. We performed a retrospective case-control analysis of 1284 patients with HS and controls matched for age, sex, race and calendar year between 1 January 1999 and 9 September 2019. BMI 7years prior to first HS diagnosis, and rate of BMI change, were compared for patients with HS and controls using linear mixed effects models. Baseline BMI was higher among patients with HS than controls [mean difference 3·03kgm-2 , 95% confidence interval (CI) 2·44-3·62; P<0·001)]. This difference was larger for women [mean difference 3·37kgm-2 (95% CI 2·73-4·01)] than men [mean difference 1·27kgm-2 (95% CI-0·20-2·73; interaction P=0·01)], and for patients with HS diagnosed before age 40years [mean difference 4·10kgm-2 (95% CI 3·15-5·06)] than those diagnosed after age 40years [mean difference 2·38kgm-2 (95% CI 1·63-3·12; interaction P<0·001)]. Prior to diagnosis, average annual increase in BMI among patients with HS was slightly higher than controls. There was no statistically significant change in annual BMI among patients with HS following diagnosis. Baseline BMI and, to a lesser extent, rate of BMI change appear to be risk factors for developing HS. The influence of BMI may play a larger role among female patients and younger patients.