Exploring the Severity Strata of Disease Activity and Repigmentation in Vitiligo Based on Validated Physician Global Assessment (PGA) Scores.

Background/Objectives: There is currently no guidance on how to interpret the global degrees of activity (worsening) and repigmentation (improvement) in vitiligo. Stratification into global degrees can be completed for static evaluations (e.g., visible disease activity signs) and dynamic assessments (e.g., evolution over time). For the latter, the Vitiligo Disease Activity Score (VDAS 15&60 ) and Vitiligo Disease Improvement Score (VDIS 15&60 ) were recently validated. Methods : In the current study, a Physician Global Assessment (PGA) for disease activity (worsening) and repigmentation (improvement) was evaluated for validity (construct) and reliability (inter- and intrarater) based on a photo set of 66 patients. Subsequently, the PGA activity (worsening) and repigmentation (improvement) were used to stratify the Vitiligo Extent Score plus (VESplus), VDAS 15&60 or VDIS 15&60 into three global categories (slightly, moderately and much worse/improved), based on ROC analysis. Results : For the VESplus, cut-off values for the categories 'slightly, moderately and much worse' were >0.3%, >27.71% and >128.75% BSA (relative changes in the affected total BSA), respectively. For the categories 'slightly, moderately and much improved', they were >0%, >4.87% and >36.88% BSA (relative changes in the affected total BSA), respectively. The optimal cut-off values of the number of active (VDAS 15 ) body areas were >0 areas for slightly worse, >2 areas for moderately worse and >7 for much worse. For VDIS 15 , the cut-off values for slightly improved and moderately improved were >0 and >1. For VDAS 60 and VDIS 60 , the cut-off points were >0.5, >3, >9.5 and >0.5 and >1.5, respectively. The results should be interpreted with caution in patients with extensive vitiligo due to the rather limited disease extent of the included patient population (VESplus (median: 3.2%)). Conclusions : This research will aid in the development of more detailed international definitions.