Importance: Few simplified instruments exist for use in hidradenitis suppurativa (HS) trials.
Objective: To assess psychometric properties of the Hidradenitis Suppurativa Investigator Global Assessment (HS-IGA) score using a clinical trial data set.
Design, setting, and participants: This retrospective analysis of a phase 2 randomized double-blind, placebo-controlled, active-reference arm trial (UCB HS0001) included adults with moderate-to-severe HS.
Exposures: Trial participants were randomized at baseline to receive bimekizumab, adalimumab, or placebo.
Main outcomes and measures: The HS-IGA score at prespecified time points up to 12 weeks after randomization.
Results: The HS-IGA score showed strong convergent validity with IHS4 and HS-PhGA scores at baseline (Spearman correlation, 0.86 [P < .001] and 0.74 [P < .001], respectively) and at week 12 (Spearman correlation, 0.73 [P < .001] and 0.64 [P < .001], respectively). The HS-IGA scores assessed during predosing visits at screening and baseline showed good test-retest reliability (intraclass correlation coefficient [ICC] = 0.92). At week 12, HS-IGA responders were significantly associated with HiSCR-(50/75/90) responders (χ2 = 18.45; P < .001; χ2 = 18.11; P < .001; and χ2 = 20.83; P < .001, respectively). The HS-IGA score was predictive of HiSCR-50/75/90 and HS-PhGA response at week 12 (AUC, 0.69, 0.73, 0.85, and 0.71, respectively). However, the HS-IGA as a measure of disease activity showed low predictive validity with patient-reported outcomes at week 12.
Conclusions and relevance: The HS-IGA score demonstrated good psychometric properties compared with existing measures and may be considered for use as an end point in clinical trials for HS.