Association of Vitiligo and Alopecia Areata With Atopic Dermatitis: A Systematic Review and Meta-analysis.

IMPORTANCE Previous studies found conflicting results as to whether atopic dermatitis (AD) is increased in patients with vitiligo and alopecia areata (AA). OBJECTIVE To compare the prevalence of AD between patients with either vitiligo or AA and those without these disorders by performing a meta-analysis of observational studies. DATA SOURCES MEDLINE, EMBASE, Cochrane Library, Google Scholar, and a manual search of 12 additional journals between 1946 and April 5, 2014. STUDY SELECTION Observational studies published in any language that compared the prevalence of AD among patients with and without either vitiligo or AA. DATA EXTRACTION AND SYNTHESIS Data were extracted by 2 independent investigators. Quality of evidence was assessed using the Newcastle-Ottawa Scale and Methodological Evaluation of Observational Research checklist. A meta-analysis of studies assessing AD, vitiligo, and/or AA was performed using a fixed-effects model to estimate pooled odds ratios (ORs). Subset analyses were performed for childhood vs adult-onset vitiligo and alopecia totalis or alopecia universalis vs patchy alopecia. MAIN OUTCOMES AND MEASURES Self-reported and/or physician-diagnosed AD, vitiligo, and AA. RESULTS In total, 16 studies of vitiligo and 17 studies of AA were included in the review. In the pooled analysis of the studies that included control patients without vitiligo (n = 2) and control patients without AA (n = 3), patients with vitiligo (Cochran-Mantel-Haenszel OR, 7.82; 95% CI, 3.06-20.00, P < .001) or AA (OR, 2.57; 95% CI, 2.25-2.94, P < .001) had significantly higher odds of AD than did control patients without these disorders. Pooled analysis of 3 studies found higher odds of AD in patients with early-onset vitiligo (<12 years) compared with those with late-onset vitiligo (OR, 3.54; 95% CI, 2.24-5.63, P < .001). Pooled analysis of 4 studies found higher odds of AD in patients with alopecia totalis or alopecia universalis compared with those with patchy alopecia (OR, 1.22; 95% CI, 1.01-1.48, P = .04). CONCLUSIONS AND RELEVANCE Patients with either vitiligo, especially early-onset disease, or AA, especially alopecia totalis or alopecia universalis, have significantly increased risk for AD.