Increased ambient outdoor temperatures are associated with increased disease flaring in hidradenitis suppurativa.

Despite evidence to suggest a relationship between time of year and hidradenitis suppurativa (HS) flaring, no studies have been conducted to date to establish a relationship directly between temperature and flaring. In this study, we aim to validate a classification approach based on administrative data for identifying medical encounters that likely represent HS flares in patient with a known diagnosis of HS within the Mass General Brigham Health System (MGB) and examine the relationship between average daily temperatures and HS disease flaring among patients in Boston. This is a retrospective cohort study. Participants were individuals with HS presenting to emergency departments or dermatology outpatient clinics with disease flares between January 2017 and January 2022. The average number of encounters for HS flares was compared with the temperature for that day and the 3- and 7-day periods prior. There were 2567 patient encounters for HS flares included in the study. Of the total identified HS flares, 75.6% occurred in females and 39.1% occurred in patients who identified as Black. Uniformly small but statistically significant relationships were noted between increased temperature and presentations for hidradenitis suppurativa flare with the highest correlation coefficient (0.0768) noted with a 3-day lag time between the heat experienced and day of presentation for flare. Increased temperature is associated with a small, but statistically significant increase in HS disease flaring. As such, HS disease flaring may rise as global temperatures do, suggesting an increase in the global burden of HS as climate change persists.