title: Low 25-hydroxyvitamin D levels are associated with vitiligo: a systematic review and meta-analysis.
abstract: 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.
authors.affiliation: Department of Internal Medicine, Bassett Medical Center and Columbia University College of Physicians and Surgeons, Cooperstown, NY, USA.|Department of Preventive and Social Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Sikarin
authors.initials: S
authors.lastname: Upala
authors.affiliation: Department of Internal Medicine, Bassett Medical Center and Columbia University College of Physicians and Surgeons, Cooperstown, NY, USA.|Department of Preventive and Social Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Anawin
authors.identifier: http://orcid.org/0000-0002-3662-4136
authors.initials: A
authors.lastname: Sanguankeo
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014820:Vitiligo / Q000097:blood* / Q000453:epidemiology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: cholecalciferol; meta-analysis; pigmentation disorders; vitamin D; vitiligo