Reliability, Validity and Feasibility of the Vitiligo Extent Score (VES) and Self-Assessment Vitiligo Extent Score (SA-VES) Among Vitiligo Patients: A Cross-Cultural Validation

Abstract

Background The Vitiligo Extent Score (VES) and Self-Assessment Vitiligo Extent Score (SA-VES) have not been formally validated in Thai population. Objective To evaluate reliability, validity and feasibility of the VES and SA-VES in Thai vitiligo patients. Methods Vitiligo lesions from 100 patients were evaluated by 2 independent dermatologists using VES and Vitiligo Area Scoring Index (VASI). Reliability was assessed by comparing VES scores between physicians. Validity was determined by comparison among the VES, VASI, and SA-VES instruments. Patients scored their vitiligo severity using the SA-VES. Results The reliability of the VES was excellent (inter-rater reliability: 0.997, 95% confidence interval: 0.995–0.998). There was very strong correlation between the VES and VASI (r=0.976, p<0.001), and strong correlation between the VES and SA-VES (r=0.890, p<0.001), and between the VASI and SA-VES (r=0.866, p<0.001). Moderate correlation among the VES, VASI, and SA-VES was observed in patients with segmental or <1% body surface area (BSA) vitiligo. Ninety-five percent of patients rated the SA-VES as easy to moderately easy. Conclusion The VES has reliability and validity comparable to that of the VASI. The SA-VES is an user-friendly instrument that correlated well with physicians’ scoring methods in patients with non-segmental or >1% BSA vitiligo.