Racial characteristics of alopecia areata in the United States

Background: Epidemiologic studies on the association between race and alopecia areata (AA) are limited. Objective: To characterize racial differences of AA in the United States. Methods: Cross-sectional study of self-registered AA patients and noncases in the National Alopecia Areata Registry (NAAR). We evaluated odds of AA and its subtypes for 5 ethnic/racial groups using logistic regression. A sex-stratified analysis and a sensitivity analysis among dermatologist-confirmed cases were also performed. Results: We identified 9340 AA patients and 2064 noncases. Compared with whites, African Americans had greater odds of AA (odds ratio, 1.77; 95% confidence interval, 1.37-2.28) and Asians had lower odds (odds ratio, 0.40; 95% confidence interval, 0.32-0.50) of AA. The results were consistent in AA subtypes, dermatologist-confirmed cases, and by sex. Limitations: Residual confounding due to limited number of covariates. Recall or recruitment bias not representative of the entire disease spectrum. Also, outcome misclassification was possible because not all AA cases in the registry were confirmed by dermatologists. Conclusion: Our findings suggest higher odds of AA in African Americans and lower odds in Asians compared with whites. Future studies examining racial disparity in AA from clinical and genetic perspectives are warranted for a better understanding of the disease pathogenesis.