Low 25-hydroxyvitamin D levels are associated with vitiligo: a systematic review and meta-analysis.

BACKGROUND

Vitamin D deficiency is associated with a number of autoimmune diseases. We completed a meta-analysis of observational studies to establish whether there was a relationship between hypovitaminosis D and the autoimmune skin disease vitiligo.

METHODS

Comprehensive search was applied in the MEDLINE and EMBASE databases from their inception to December 2015. Inclusion criteria were observational studies that assessed 25-hydroxyvitamin D (25(OH)D) levels in adults with vitiligo. The main outcome was the mean difference in serum 25(OH)D level between patients with vitiligo and controls.

RESULTS

Our search strategy identified 383 articles; seventeen studies met the criteria for full-length review and seven studies, containing the data of 1200 patients, were included in a random-effects model meta-analysis. The pooled mean difference in serum 25-hydroxyvitamin D concentration between patients with vitiligo and controls was -7.45 ng/ml (95% confidence interval, -12.99 to -1.91, P-value = 0.01). The between-study heterogeneity (I(2) ) was 96%, P = value<0.001.

CONCLUSIONS

This meta-analysis identifies a significant relationship between low 25-hydroxyvitamin D levels and vitiligo, but does not prove causation. Our findings emphasize the importance of measuring 25-hydroxyvitamin D levels in patients with vitiligo. Further studies will be needed to establish whether vitamin D supplementation in this population improves the outcome of vitiligo.