Measuring success in HS treatment from the physician's and the patient's perspective

Hidradenitis suppurativa (HS) is a chronic, debilitating inflammatory skin disease with substantial quality-of-life impact. Accurate measurement of treatment success requires validated instruments capturing both physician-assessed disease activity and patient-reported symptom burden. Despite an expanding toolkit, consensus on defining remission, optimal control, resolution and progression remains elusive. This review provides a comprehensive overview of key clinician- and patient-reported outcome measures in HS, evaluates their psychometric properties and critically addresses minimal clinically important difference, remission, optimal control, resolution and progression. The emerging role of tissue damage, fibrosis assessment, imaging and molecular pathology in redefining treatment success is also discussed. A narrative literature review was conducted via systematic PubMed and MEDLINE searches through March 2026, with emphasis on publications from the EHSF, the HiSTORIC consortium, the Global VOICE project, and recent clinical trial data. HiSCR has been the most widely used primary endpoint but is limited by its exclusion of patients with fewer than three abscess-nodule lesions and inability to capture tunnel improvement. The IHS4 is a robust dynamic scoring system incorporating draining tunnels with fourfold weighting; its derivative IHS4-55 provides a clinically meaningful response threshold regardless of baseline lesion count. HS-IGA demonstrates high test-retest reliability. Among patient-reported outcomes, HiSQOL is the preferred HS-specific quality-of-life instrument (validated MID: 20-21 points), while DLQI remains the most used non-specific tool. The Pain Index effectively evaluates nociceptive pain. Formal definitions of remission, optimal control and progression are being developed through the HiSTORIC treat-to-target initiative. Ultrasound-based fibrosis grading and ultra-high-frequency imaging reveal clinically underscored tissue damage; long-wave infrared thermography may serve as a reproducible inflammatory biomarker. Optimizing HS outcomes requires integration of dynamic physician-reported scores, HS-specific patient-reported outcomes and emerging tissue damage and inflammation metrics. Consensus definitions for remission, minimal disease activity and progression represent the next frontier in HS management.