Characterization of Hidradenitis Suppurativa Phenotypes: A Multidimensional Latent Class Analysis of the National Italian Registry IRHIS.

ABSTRACT In spite of the large heterogeneity, limited data exist on hidradenitis suppurativa (HS) phenotypes. To identify the HS phenotypes that best explain the disease heterogeneity, a cross-sectional study using Latent Class Analysis (LCA) was conducted on a cohort of patients examined at 17 dermatological centers participating in the Italian Registry of HS (IRHIS), and being enrolled between January 2015 and January 2020. Overall 965 patients aged 32.0±12.4 years (mean±SD) were evaluated. A three-class model in LCA best fitted the data. Patients in latent class 1 (LC1) (20.1%) were females, mostly obese, with a high probability of axillary-groin (0.85) and mammary (0.59) lesions, and the highest HS severity. LC2 patients (29.6%) were nonobese males, with moderate disease severity, a high probability of gluteal (0.50) and genital (0.17) lesions, besides axillary-groin involvement, and with acne and pilonidal cysts. LC3 patients (50%) were nonobese females with a milder disease mostly limited to axillary (0.52) and groin areas (0.66). The stratification of HS patients into a severe "axillary-mammary-groin" phenotype with predominantly anterior-body involvement in females, an "axillary-gluteal-groin" phenotype of intermediate severity mainly affecting males in the posterior-body areas, and an "axillary-groin" phenotype with mildest clinical symptoms and limited skin involvement may help optimizing HS management.