Meaningful Changes in What Matters to Individuals with Vitiligo: Content Validity and Meaningful Change Thresholds of the Vitiligo Area Scoring Index (VASI).

ABSTRACT

INTRODUCTION: This study explored patients' and dermatologists' priority outcomes for treatment to address, clinical outcome assessments (COA) for use in vitiligo clinical trials, and perceptions of within-patient meaningful change in facial and total body vitiligo. METHODS: Semistructured, individual, qualitative interviews were conducted with patients living with non-segmental vitiligo in the USA and with expert dermatologists in vitiligo. Concept elicitation discussions included open-ended questions to identify patient priority outcomes. Vitiligo COAs were reviewed by dermatologists. Tasks were completed by patients to explore their perceptions of meaningful changes in vitiligo outcomes; dermatologists' opinions were elicited. Data were analyzed using thematic methods; meaningful change tasks were descriptively summarized. RESULTS: Individuals with vitiligo (N = 60) included adults (n = 48, 63% female) and adolescents (n = 12, 67% female). All Fitzpatrick Skin Types were represented. Eight (13%) were first- or second-generation immigrants to the USA. Expert dermatologists (N = 14) participated from the USA (n = 8), EU (n = 4), India (n = 1), and Egypt (n = 1). All individuals with vitiligo reported experiencing skin depigmentation; an observable clinical sign of vitiligo. Most confirmed that lesion surface area (n = 59/60, 98%) and level of pigmentation (n = 53/60, 88%) were important to include in disease assessments. Following an explanation, participants (n = 49/60, 82%) felt that the Facial Vitiligo Area Scoring Index (F-VASI) measurement generally made sense and understood that doctors would use it to assess facial vitiligo. Most participants felt that a 75% (n = 47/59, 80%) or 9 0% improvement in their facial vitiligo would be indicative of treatment success (n = 55/59, 93%). In the context of evaluating a systemic oral treatment for vitiligo, dermatologists perceived a 75% improvement on the F-VASI as successful (n = 9/14, 64%). Regarding the Total VASI (T-VASI) score, n = 30 participants considered 33% improvement as treatment success; an additional n = 10 endorsed 50% improvement and a further n = 5 endorsed 75% improvement. Clinicians most frequently identified 50% (n = 6/14, 43%) or 75% (n = 4/14, 29%) improvement in T-VASI as successful. CONCLUSION: Repigmentation is a priority outcome for patients. The VASI was considered an appropriate tool to assess the extent of vitiligo. A minimum 75% improvement from baseline in the F-VASI and minimum 50% improvement from baseline in the T-VASI were identified as within-patient clinically meaningful thresholds.