Validation of the Hidradenitis Suppurativa Investigator Global Assessment A Novel Hidradenitis Suppurativa-Specific Investigator Global Assessment for Use in Interventional Trials

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 (chi(2) = 18.45; P <.001; chi(2) = 18.11; P <.001; and chi(2) = 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.