Validation of the Vitiligo Noticeability Scale: A patient-reported outcome measure of vitiligo treatment success

Abstract

Background Patient-reported outcome measures are rarely used in vitiligo trials. The Vitiligo Noticeability Scale (VNS) is a new patient-reported outcome measure assessing how 'noticeable' vitiligo patches are after treatment. The noticeability of vitiligo after treatment is an important indicator of treatment success from the patient's perspective. Objectives To evaluate the construct validity, acceptability and interpretability of the VNS. Methods Clinicians (n = 33) and patients with vitiligo (n = 101) examined 39 image pairs, each depicting a vitiligo lesion pre- and post-treatment. Using an online questionnaire, respondents gave a global assessment of treatment success and a VNS score for treatment response. Clinicians also estimated percentage repigmentation of lesions (< 25%; 25-50%; 51-75%; > 75%). Treatment success was defined as 'yes' on global assessment, a VNS score of 4 or 5, and > 75% repigmentation. Agreement between respondents and the different scales was assessed using kappa (κ) statistics. Results Vitiligo Noticeability Scale scores were associated with both patient- and clinician-reported global treatment success (κ = 0·54 and κ = 0·47, respectively). Percentage repigmentation showed a weaker association with patient- and clinician-reported global treatment success (κ = 0·39 and κ = 0·29, respectively). VNS scores of 4 or 5 can be interpreted as representing treatment success. Images depicting post-treatment hyperpigmentation were less likely to be rated as successful. Conclusions The VNS is a valid patient-reported measure of vitiligo treatment success. Further validation of the VNS is required, using larger sets of clinical pre- and post-treatment images, affecting a wider range of anatomical sites.