Defining Minimal Disease Activity in Hidradenitis Suppurativa: A New Clinical Target

Hidradenitis suppurativa (HS) is a chronic, relapsing inflammatory skin disease lacking a standardized definition of disease control. While minimal disease activity (MDA) serves as a validated treatment target in psoriasis and atopic dermatitis, no equivalent framework exists for HS, limiting the implementation of treat-to-target strategies.

To propose and validate clinically relevant MDA criteria for HS, integrating objective measures and patient-reported outcomes in a real-world cohort.

Prospective, single-center, and observational study including all patients classified as well-controlled between April 2024 and January 2025. Sociodemographic, clinical, and therapeutic data were collected. In a paired analysis, a subgroup with prior moderate/poor control was compared against their pre-control.

Of 547 patients, 170 were classified as well-controlled. At assessment, 85.9% (146/170) had no active lesions, with a mean Localized Activity Index (LAI)-active areas/total affected areas-of 6%, and an International Hidradenitis Suppurativa Severity Score System (IHS4) of 0.38 ± 1.07. Symptomatic burden was minimal, with a mean global visual analog scale (VAS) of 1.24. In 114 paired patients, significant improvements were observed across all domains, including a 92% reduction in LAI and a 97% reduction in IHS4 (P < .0001). Factor analysis revealed 2 key dimensions-objective inflammation and patient-perceived symptoms-forming the basis for the proposed MDA definition: LAI ≤0.3, IHS4 ≤7, global/pain/suppuration VAS ≤3, and absence of structural progression. These criteria correctly identified 82% of well-controlled patients.

This study introduces the first operational definition of MDA in HS, empirically derived and clinically feasible. Adoption of this framework could harmonize disease assessment, guide therapeutic targets, and advance precision management in HS.