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

Background A temporal relationship between hidradenitis suppurativa (HS) and obesity has not been established. Objectives To compare baseline body mass index (BMI) and change in BMI for patients with HS and controls before and after diagnosis. Methods 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 7 years prior to first HS diagnosis, and rate of BMI change, were compared for patients with HS and controls using linear mixed effects models. Results Baseline BMI was higher among patients with HS than controls [mean difference 3 center dot 03 kg m(-2), 95% confidence interval (CI) 2 center dot 44-3 center dot 62; P < 0 center dot 001)]. This difference was larger for women [mean difference 3 center dot 37 kg m(-2) (95% CI 2 center dot 73-4 center dot 01)] than men [mean difference 1 center dot 27 kg m(-2) (95% CI - 0 center dot 20-2 center dot 73; interaction P = 0 center dot 01)], and for patients with HS diagnosed before age 40 years [mean difference 4 center dot 10 kg m(-2) (95% CI 3 center dot 15-5 center dot 06)] than those diagnosed after age 40 years [mean difference 2 center dot 38 kg m(-2) (95% CI 1 center dot 63-3 center dot 12; interaction P < 0 center dot 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. Conclusions 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.

Automated summary

The study revealed that baseline BMI and rate of BMI change are risk factors for developing HS, with a stronger influence among female and younger patients.