The Alopecia Areata Investigator Global Assessment scale: a measure for evaluating clinically meaningful success in clinical trials

Background Content-valid and clinically meaningful instruments are required to evaluate outcomes of therapeutic interventions in alopecia areata (AA). Objectives To develop an Investigator's Global Assessment (IGA) to interpret treatment response in AA treatment studies. Methods Qualitative interviews were conducted in the USA with expert dermatologists and with patients with AA who had experienced >= 50% scalp-hair loss. Thematic data analysis identified critical outcomes and evaluated the content validity of the new IGA. Results Expert clinicians (n = 10) judged AA treatment success by the amount of scalp-hair growth (median 80% scalp hair). Adult (n = 25) and adolescent (n = 5) patients participated. Scalp-hair loss was the most bothersome AA sign/symptom for most patients. Perceived treatment success - short of 100% scalp hair - was the presence of similar to 70-90% scalp hair (median 80%). Using additional clinician and patient insights, the Alopecia Areata Investigator Global Assessment (AA-IGA (TM)) was developed. This clinician-reported outcome assessment is an ordinal, static measure comprising five severity categories of scalp-hair loss. Nearly all clinicians and patients in this study agreed that, for patients with >= 50% scalp-hair loss, successful treatment would be hair regrowth resulting in <= 20% scalp-hair loss. Conclusions We recommend using the Severity of Alopecia Tool to assess the extent (0-100%) of scalp-hair loss. The AA-IGA is a robust ordinal measure providing distinct and clinically meaningful gradations of scalp-hair loss that reflects patients' and expert clinicians' perspectives and treatment expectations.