New Insights on the Vitiligo Area Scoring Index: Validity and Change Thresholds Revealed

Original Article:  Psychometric Properties and Meaningful Change Thresholds of the Vitiligo Area Scoring Index

What are the key takeaways of this article?

The Total Vitiligo Area Scoring Index (T-VASI) and Facial VASI (F-VASI) are tools frequently used to measure vitiligo severity, especially for clinical trials assessing treatment outcomes. While these indices are commonly used in research, clinically meaningful improvement thresholds for vitiligo repigmentation have not yet been clearly established.

A recent mixed-methods study aimed to evaluate the concept validity, measurement performance, and meaningful change thresholds for T-VASI and F-VASI in patients with nonsegmental vitiligo. The study included a secondary analysis of a phase 2 multicenter randomized clinical trial, along with embedded qualitative interviews, conducted across 35 sites in Canada, France, Japan, and the US. The study included 164 adult patients with nonsegmental vitiligo who had baseline scores of T-VASI ≥5 and F-VASI ≥0.5. The psychometric performance of T-VASI and F-VASI was assessed using both clinician- and patient-reported measures.

The results showed strong test-retest reliability for both T-VASI and F-VASI, with intraclass correlation coefficients of 0.98 and 0.99, respectively, for patients with stable vitiligo between baseline and week 4. Additionally, there were moderate to strong correlations between T-VASI and physician-reported severity assessments (r = 0.63-0.65), as well as between F-VASI and face-specific physician severity scores (r = 0.65-0.71). Improvements in VASI scores over 24 weeks were associated with increased repigmentation as reported by physicians and patients.

The study identified that reductions of 30% in T-VASI and 50% in F-VASI scores indicate meaningful repigmentation, thereby suggesting that these are conservative yet relevant benchmarks for clinically meaningful change. The findings suggest that commonly used thresholds, such as T-VASI 50 and F-VASI 75, may be overly conservative and that lower thresholds can capture meaningful improvements for patients with non-segmental vitiligo.

The study’s limitations include potential variability in scoring across sites, a limited sample size for qualitative analysis, and a lack of longitudinal data beyond 24 weeks. The findings highlight the need for further research to refine these thresholds and confirm their clinical significance over longer durations. Despite these limitations, this study provides valuable insights into establishing meaningful change thresholds for vitiligo severity assessments, supporting the T-VASI and F-VASI as reliable tools for future clinical trials.

Publication Date: December 2nd, 2024

Reference: Ezzedine K, Soliman AM, Camp HS, et al. Psychometric Properties and Meaningful Change Thresholds of the Vitiligo Area Scoring Index. JAMA Dermatol. Published online October 30, 2024. doi:10.1001/jamadermatol.2024.4534

Summary By: Megan Lowe