Reply to: Serum Vitamin D Level and Disease Severity of Alopecia Areata: A Meta-Regression Analysis

The authors responded to Dr. Yao's comments on their systematic review and meta-analysis regarding the relationship between vitamin D levels and the severity of alopecia areata (AA). They acknowledged the importance of exploring this correlation and conducted a new meta-regression analysis including 10 studies. This analysis redefined a severe AA group and used the Severity of Alopecia Tool (SALT) scores to evaluate disease severity. The results showed a slightly negative but nonsignificant correlation between serum vitamin D levels and the proportion of severe AA, which was consistent with Dr. Yao's findings. The authors also referenced other studies that found a negative correlation between vitamin D levels and AA severity, and the expression of vitamin D receptors in hair follicles. They concluded that vitamin D deficiency might be one of many factors contributing to AA and called for more research to clarify vitamin D's role in AA pathogenesis. The meta-regression was limited by the small number of studies included.