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

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.