Supplementary Material for: Prevalence of hidradenitis suppurativa in Poland

Introduction: Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition characterized by recurrent boils or abscesses. Its prevalence varies globally, yet specific data from Poland are limited. This study aims to determine the prevalence of HS among adults in Poland, utilizing standardized methods as part of the Global Hidradenitis Suppurativa Atlas (GHiSA) initiative. Methods: This monocenter study was conducted at internal medicine departments of University Hospital of Wroclaw. In the study, participants were individuals accompanying patients administered to the hospital, excluding individuals under 18 years of old, pregnant women, and those deemed incapable of participating. A self-administered screening questionnaire for HS diagnosis was utilized. Physical examinations and Hurley score assessments were conducted for participants reporting HS symptoms. In addition, approximately 10% of participants who did not report any HS symptoms were tested to determine the false-negative response rate. Statistical analysis was performed using R Project for Statistical Computing and Statistica 13.3 software. Results: Out of 940 adults approached, 932 participated in the study. 21 participants reported HS symptoms, with 14 individuals diagnosed with HS upon examination. Additionally, 1 participant without reported symptoms was diagnosed with HS. The estimated prevalence of HS among the Polish adult population was 1.61% (95%CI 0.90–2.50%). The screening questionnaire exhibited a sensitivity and specificity of 93%, with a positive predictive value (PPV) of 67% and negative predictive value (NPV) of 99%. Conclusion: This study shed some light on the prevalence of HS in Poland, indicating that it is a more common condition than previously reported in the literature. It can contribute to understanding the epidemiology of HS in Poland and may aid in improving diagnosis and management strategies for affected individuals.