Development and validation of a vitiligo-specific quality-of-life instrument (VitiQoL)

Background: Vitiligo significantly affects a person's health-related quality of life (HRQL). Although a small number of generic, and disease-specific, dermatologic HRQL measures exist, currently no vitiligo-specific instrument is available to capture disease-targeted concerns and issues. Objective: We sought to develop and validate a vitiligo-specific self-report instrument for HRQL. Methods: A pool of vitiligo-specific items was created based on in-depth interviews with patients with vitiligo (n = 16) and their responses to items in several previously validated HRQL measures. These items comprising our new instrument, VitiQoL, along with Skindex-16 and Dermatology Life Quality Index were administered to patients with vitiligo (n = 90) at two academic centers. This new instrument was validated using psychometric analysis. Results: The VitiQoL items showed high internal consistency (Cronbach alpha = 0.935). Exploratory factor analysis demonstrated 3 factors: participation limitation, stigma, and behavior. Concurrent validity was evidenced by large correlations between self-reported severity and VitiQoL scores (r = 0.51). Known groups validity was demonstrated for the VitiQoL behavior subscale between individuals with exposed and unexposed patches (P = .01). Convergent validity was shown by strong correlations between VitiQoL and outside dermatology scales measuring similar constructs (Skindex-16, r = 0.82; Dermatology Life Quality Index, r=0.83). Limitations: Potential selection bias was a limitation as most patients were recruited from academic centers. Reliability of the instrument was tested only with internal consistency and not reproducibility. Responsiveness of the instrument was not tested because of the prolonged time course necessary to observe clinically significant change in vitiligo. Conclusion: VitiQoL is a reliable and valid HRQL instrument.