The first operational definition of minimal disease activity in hidradenitis suppurativa (HS) has been proposed, combining objective disease measures and patient-reported outcomes to provide a practical treatment target for routine clinical practice.

The management of HS has evolved significantly with the introduction of biologic therapies, raising expectations around disease control and long-term outcomes.

However, unlike psoriasis and atopic dermatitis, HS lacks a standardised definition of disease control, making it difficult to consistently implement treat-to-target strategies.

Researchers therefore sought to define and validate clinically relevant criteria for minimal disease activity in HS using real-world clinical data.

Published in the Journal of Cutaneous Medicine and Surgery, the prospective observational study was conducted at a dedicated HS clinic in Spain between April 2024 and January 2025.

Participants included 547 adult patients with HS, of whom 170 had well-controlled disease. A subgroup of 114 patients with documented periods of moderate or poor disease control was also included in a paired analysis comparing disease status before and after achieving control.

Defining disease control for HS

Objective measures of inflammatory activity, including the International Hidradenitis Suppurativa Severity Score System (IHS4) and a newly developed Localised Activity Index (LAI), were assessed alongside patient-reported assessments of disease severity, pain and suppuration using visual analogue scales (VAS).

The primary outcome was the identification of clinical characteristics associated with a well-controlled disease state. Among the patients classified as well controlled, 85.9% had no active inflammatory lesions.

Mean HS disease activity was low, with an average IHS4 score of 0.38 and an LAI of 6%. Symptom burden was also minimal, with mean global, pain and suppuration VAS scores all below 1.5.

In the paired analysis, substantial improvements were observed after patients achieved disease control. Mean IHS4 scores decreased by almost 97%, while LAI fell by more than 92%.

Significant reductions were also seen in pain, suppuration and overall disease severity scores. No patients experienced an increase in active anatomical areas or draining tunnels, indicating stable structural disease control.

Using receiver operating characteristic analyses and multivariable modelling, the authors proposed that minimal disease activity should be defined by the fulfilment of all the following criteria: LAI ≤0.3, IHS4 ≤7, global VAS ≤3, pain VAS ≤3, suppuration VAS ≤3, and no increase in active anatomical areas or draining tunnels.

Potential framework for treat-to-target management

The proposed framework correctly identified 82.2% of patients with HS who were considered well controlled in routine practice.

The authors suggested that the proposed minimal disease activity criteria provide an intermediate but clinically meaningful therapeutic target for patients in whom complete remission from HS may not be achievable.

Importantly, the framework relies entirely on clinical and patient-reported measures and does not require laboratory testing, potentially facilitating implementation in routine dermatology practice.

Limitations noted by the authors were the study’s single-centre design, which may affect generalisability, and the use of expert clinical judgement to determine disease control status rather than a validated gold standard.

Although the proposed HS minimal disease activity criteria underwent internal validation and were supported by robust statistical analyses, the authors explained that multicentre validation studies are already underway to refine the proposed thresholds and assess their broader applicability.

If validated, the framework could help to standardise disease assessment, inform treatment targets and support future research into treat-to-target approaches in HS. The authors also suggested that its simplicity may facilitate the development of digital tools to help clinicians to assess disease control and treatment response.

Reference
García-Moronta C et al. Defining minimal disease activity in hidradenitis suppurativa: a new clinical target. J Cutaneous Med Surg 2026;2034754261442925.