Validation of the Hidradenitis Suppurativa Investigator Global Assessment

Abstract

Few simplified instruments exist for use in hidradenitis suppurativa (HS) trials. To assess psychometric properties of the Hidradenitis Suppurativa Investigator Global Assessment (HS-IGA) score using a clinical trial data set. 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. Trial participants were randomized at baseline to receive bimekizumab, adalimumab, or placebo. The HS-IGA score at prespecified time points up to 12 weeks after randomization. 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. 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.