Vitamin D and its Analogs in Treatment of Mild to Moderate Alopecia Areata: Systematic Review and Meta-Analysis.

Recently, vitamin D3 and its analogs have shown therapeutic potential in the treatment of alopecia areata (AA). The aim of this study was to evaluate the safety/efficacy of topical/intralesional vitamin D3 and its analogs for treatment of mild-to-moderate AA. We included clinical trials that evaluated topical/intralesional vitamin D3 and its analogs for the treatment of AA. Response rates were defined as either achieving a Score 4 (S4) response on the hair regrowth scale (≥75% regrowth) or reduction in the mean Severity of Alopecia Tool (SALT) score after treatment. The overall success rate of vitamin D3 and its analogs in the treatment of mild-to-moderate AA is about 53.75%. Both intralesional and topical vitamin D3 (odds ratio = 3.20; 95% confidence interval (CI): [1.24, 8.24] and mean difference (MD) = 2.11; 95% CI: [-1.10, 5.31], respectively) are effective in the treatment of mild-to-moderate AA. Additionally, topical vitamin D3 analogs had a synergistic effect when used in combination with other treatments including topical corticosteroids and NB-UVB (MD = 0.62; 95% CI: [-0.24, 1.48] and MD = 1.34; 95% CI: [0.96, 1.71]), respectively. Intralesional vitamin D3 showed lower efficacy compared to intralesional corticosteroid and topical bimatoprost (MD = -4.73; 95% CI: [-7.38, -2.08]). No serious adverse events were associated with the use of vitamin D3 and its analogs. Small number of randomized clinical trials, lack of baseline vitamin D3 levels and co-morbid autoimmune conditions assessment. Vitamin D3 and its analogs may serve as a safe, inexpensive alternative for mild-to-moderate patchy AA, either as a mono-therapeutic agent or as an adjuvant for more severe cases.