Assessing the validity, responsiveness and meaningfulness of the Hidradenitis Suppurativa Clinical Response (HiSCR) as the clinical endpoint for hidradenitis suppurativa treatment

Quantification of disease severity supports the development of evidence-based treatments. Assessments to capture clinical improvement in hidradenitis suppurativa (HS) can be improved.This study aimed to validate the Hidradenitis Suppurativa Clinical Response (HiSCR), which is defined as a ≥ 50% reduction in inflammatory lesion count (sum of abscesses and inflammatory nodules, AN), and no increase in abscesses or draining fistulas in HS when compared with baseline as a meaningful clinical endpoint for HS treatment.Patients with ≥ 3 ANs at baseline in a Phase II adalimumab trial for HS were included for analysis. HiSCR achievers vs. nonachievers were assessed at week 16 and week 52. Criteria measures included physician-rated assessments [Hurley stage, modified Sartorius score (MSS), and HS Physician's Global Assessment] and patient-reported outcomes (PROs: visual analogue pain scale, Dermatology Life Quality Index, and Work Productivity and Activity Impairment questionnaire). Test-retest reliability, convergent validity, responsiveness and predictive validity of HiSCR, and its meaningfulness to patients were assessed.Among 138 eligible study participants, the majority were female (69·6%) with a mean age of 36·7 years. The mean (median) MSS was 125·2 (85·5) at baseline. Test-retest reliability of the AN count was 0·91. HiSCR was significantly correlated with improvements in all physician-rated and PRO measures (Spearman's rho between -0·61 and -0·27, all P < 0·001). Improvements of all PROs in HiSCR achievers exceeded the respective meaningful improvement thresholds.In patients with HS with ≥ 3 ANs, HiSCR achievers had significant improvements in physician-rated and patient-reported HS disease severity and impact. HiSCR is a valid and meaningful endpoint for assessing HS treatment effectiveness in controlling inflammatory manifestations in this population.