A Qualitative Study to Develop and Evaluate the Content Validity of the Vitiligo Patient Priority Outcome (ViPPO) Measures.

Introduction: Vitiligo can be associated with a psychological burden, stigmatization and impaired quality of life. Tools to assess the impact of vitiligo exist; however, none were developed in line with the FDA's patient-reported outcome (PRO) Guidance for Industry. This study aimed to explore the content validity of two newly developed PRO measures to assess the impact of facial and total body vitiligo on how patients feel and function.

Methods: Draft PRO measures were developed from existing literature and input from PRO experts, a patient advocate and a clinical expert. Qualitative interviews were conducted with US participants living with vitiligo and international dermatologists with vitiligo expertise. Concept elicitation methodology explored the relevance of concepts in the draft PRO, while cognitive debriefing assessed conceptual relevance and understanding/interpretation. Items were iteratively amended/added throughout the interview study.

Results: The 60 participants included adults (n = 48, 63% female, 18-62 years old) and adolescents (n = 12, 67% female, 12-17 years old) with Fitzpatrick Skin Types I-VI. Expert dermatologists from the US (n = 8), EU (n = 4), India (n = 1) and Egypt (n = 1) participated. Concept elicitation was utilized to confirm the signs/symptoms of vitiligo and the associated impact on emotional/psychological wellbeing, social functioning, daily life and work/school. Conceptual saturation was achieved. Most participants reported impacts on their emotional/psychological wellbeing (n = 57, 95%), e.g. feeling self-conscious (n = 35, 58%). Participants reported impacts on social functioning (n = 53, 88%), e.g. vitiligo being noticed by others (n = 42, 70%). There was general consensus between participants and expert dermatologists. Cognitive debriefing confirmed that the items were well understood. Most items were conceptually relevant; feeling self-conscious and feeling frustrated were highly endorsed. Items were removed based on low conceptual relevance (feeling abandoned, skin roughness) and expected redundancy (four items), resulting in two measures with three proposed domain scores: Emotional/Psychological Wellbeing; Social Functioning; and Physical Sensation. No comprehension concerns were observed in relation to the 7-day recall period or the item response scale/options. Eight dermatologists reviewed the PRO measures, confirming comprehensiveness and relevance.

Conclusion: The draft Vitiligo Patient Priority Outcomes (ViPPO) measures evaluate the impact of facial (ViPPO-F) and total body (ViPPO-T) vitiligo on emotional/psychological and social functioning. The ViPPO measures are well understood, comprehensive and content valid for adults and adolescents with vitiligo.