Background: Alopecia areata (AA) is a chronic autoimmune disease that leads to a high psychiatric, economic and systemic disease burden. A comprehensive understanding of AA epidemiology is essential for evaluating healthcare source utilization; however, a systematic approach to summarizing epidemiological data on AA is lacking.
Objectives: To investigate systematically the global, regional and national incidence and prevalence of AA.
Methods: A structured search was conducted using the databases MEDLINE, Embase, Cochrane Library, Web of Science, SciELO and Korean Journal Database from their date of inception to 4 October 2023. Studies that reported the prevalence or incidence of AA were included. We used a Bayesian hierarchical linear mixed model to analyse prevalence estimates. The primary outcomes of our study were the global, regional and national prevalence of physician-diagnosed AA for the overall population, for adults and for children. The incidence data were summarized descriptively.
Results: In total, 88 studies from 28 countries were included in the analysis. The reported incidence of AA tended to be higher in adults aged 19-50 years, and this trend was consistent with its estimated prevalence. The reported prevalence in overall populations tended to be higher in men vs. women. The estimated lifetime prevalence rate of AA was 0.10% [95% credible interval (CrI) 0.03-0.39] in the general population worldwide, 0.12% (95% CrI 0.02-0.52) in adults and 0.03% (95% CrI 0.01-0.12) in children. The estimated prevalence of AA was highest in the Asian region and lowest in the African region.
Conclusions: In this study, 48% of the Global Burden of Disease regions had insufficient data on the prevalence or incidence of AA. Further studies are needed to provide epidemiological information on middle- and low-income countries. Our study may serve as a crucial reference in terms of healthcare policy decisions.
Alopecia areata (AA) is a chronic autoimmune disease that can have both a psychological and physical impact on patients. An understanding of in whom, when and where the disease occurs (‘epidemiology’) is important to evaluate how healthcare resources are used in AA. There is a lack of analysis of epidemiological data in AA. This study investigated the global, regional and national incidence (the number of new cases in a specific time period) and prevalence (the rate of new cases occurring in a specific population over a specific period of time) of AA by reviewing multiple databases. Studies that reported the prevalence or incidence of AA were analysed. The primary outcomes were the global, regional and national prevalence of AA diagnosed by a doctor for the overall population, for adults only and for children only. Altogether, 88 studies from 28 countries were included in the review. The incidence of AA tended to be higher in adults aged 19–50 years, and this trend was consistent with its estimated prevalence. The estimated lifetime prevalence rate (i.e. the proportion of individuals that will be affected) of AA was 0.10% in the general population worldwide, 0.12% in adults and 0.03% in children. The estimated prevalence of AA was highest in the Asian region and lowest in the African region. Overall, we found that 48% of regions did not have enough data on the prevalence or incidence of AA. Further studies are needed to provide epidemiological data on AA, especially in middle- and low-income countries. Our results will help with healthcare policy decisions.
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