Validation of the Investigator Global Assessment of Chronic Hand Eczema (IGA–CHE): a new clinician reported outcome measure of CHE severity

Abstract

The Investigator Global Assessment of Chronic Hand Eczema (IGA–CHE) is a novel Clinician-Reported Outcome measure that allows investigators to assess cross-sectional CHE global disease severity using clinical characteristics of erythema, scaling, lichenification/hyperkeratosis, vesiculation, oedema, and fissures as guidelines for overall severity assessment. This study aimed to evaluate the psychometric properties of the IGA–CHE for use as an outcome measure in CHE clinical trials and clinical practice. Psychometric analyses were performed using data from a sample of 280 patients with moderate to severe CHE from a phase 3 trial of delgocitinib cream, pooled across treatment groups. Test–retest reliability results were moderate to strong with kappa coefficients ranging from 0.63 to 0.76. Correlations with measures assessing related concepts were moderate or strong (range 0.65–0.72) and exceeded a priori hypotheses, providing evidence of convergent validity. Known-groups validity was supported by statistically significant differences between severity groups (< 0.001). Within-group effect sizes were consistently larger for improved groups compared to stable groups, providing evidence of ability to detect change. Anchor-based analyses generated within-subject meaningful change estimates ranging from – 0.8 to – 2.3. A correlation weighted average suggested a single value of – 1.7 in change from baseline. These findings provide evidence the IGA–CHE scale has strong reliability, construct validity, and ability to detect change, supporting its use as an endpoint in CHE clinical trials and clinical practice. Based on the evidence, 2-level changes in IGA–CHE score are considered a conservative meaningful change threshold; however, findings also indicate 1-level change in IGA–CHE scores reflects a clinically meaningful improvement for patients.Clinical trial registration: NCT04871711.