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

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.