Belgian patients of the European Registry for Hidradenitis Suppurativa (ERHS-Be): data, scores and phenotypes since 2015.

Introduction Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease, characterized by painful and recurrent lesions in apocrine gland-bearing skin areas. It is a heterogeneous disease, which makes assessment and data collection difficult. Questionnaires with detailed items, such as the Belgian European Registry for Hidradenitis Suppurativa (ERHS-Be), are useful to study HS and its associated comorbidities. The aim of this registry is to uncover new factors associated with HS, understand HS patients' clinical profiles and efficacy of treatments. Material and methods The ERHS-Be registry is based on questionnaires, with sections for socio-demographic data, medical and HS history, clinical examination and treatment plan. It allows identification of different clinical phenotypes and automatic calculation of severity scores. Results At present, 606 patients are included in the ERHS-Be (67% women, 33% men). Mean age at first visit is 38.5 years. Tobacco use is present in 72.6% of patients. A family history of HS is noted in 42% of patients. Comorbidities are documented in this cohort: depression is present in 43.8% of patients, arthritis in 27.8%, obesity in 31.5%, hypertension in 10.6%, diabetes mellitus in 6.4% and dyslipidemia in 12.4%. Moreover, 7.7% of patients suffer from IBD and 27.4% have a pilonidal sinus. History of severe acne is found in 32.1% of patients and psoriasis in 9.3%. Thirteen percent of women in our cohort suffer from polycystic ovarian syndrome. Severity of disease is quantified in 533 patients: for instance, Hurley I, II and III scores proportions are respectively 32.3%, 52.7% and 15%, while the mean IHS4 score is 5.2. This registry also enables determination of relative phenotype proportions in our cohort, according to different classifications. Conclusion The ERHS-Be questionnaires allow systematic and larger data collection, including detailed comorbidities, phenotypes and severity of disease. Analysis of this large database will contribute to a better understanding and management of HS, at a time where new therapeutic options are becoming available.