['Hidradenitis suppurativa (HS) is a chronic inflammatory disease involving intertriginous skin. Previous epidemiologic studies have been limited by small sample size.', 'We sought to describe the prevalence and comorbidities of HS in a large patient care database.', 'In this retrospective case-control study, we chart-validated all patients within a hospital database who received at least 1 billing code for HS between 1980 and 2013. Verified cases were matched with controls based on age, gender, and race. Prevalences of a priori selected comorbidities were compared between HS and control groups.', 'A total of 2292 patients at Massachusetts General Hospital received at least 1 code for HS. A total of 1776 cases had a validated diagnosis of HS, yielding a prevalence of 0.08%. In unadjusted analysis, all comorbidities were diagnosed significantly more in HS compared with control including (in rank order of likelihood): smoking, arthropathies, dyslipidemia, polycystic ovarian syndrome, psychiatric disorders, obesity, drug dependence, hypertension, diabetes, thyroid disease, alcohol dependence, and lymphoma (all P < .01).'] Is hidradenitis suppurativa a systemic disease with substantial comorbidity burden : a chart-verified case-control analysis?