Epidemiology and burden of alopecia areata in Taiwan: a systematic review

Introduction: Alopecia areata (AA) is a common autoimmune disorder characterized by nonscarring hair loss on the scalp and/or body, affecting individuals of all genders, ages, and races. AA can occur alongside various autoimmune, atopic, and psychiatric conditions, affecting patients' quality of life. Although AA is a relatively common condition, recent epidemiological data regarding this condition in Taiwan are lacking. Methods: This systematic literature review aimed to assess the epidemiology, risk factors, and comorbidities associated with AA in Taiwan by analyzing articles published from January 2010 to June 2024. Results: A total of 37 studies were included, with most using the National Health Insurance Research Database (NHIRD) as the data source. The annual incidence and prevalence of AA in Taiwan were estimated at 0.011 and 0.014-0.016%, respectively. The mean age of AA onset ranged from 32 to 41.2 years, with a slight male predominance. Identified risk factors included autoimmune diseases, psychiatric disorders, viral infections, and lifestyle habits, while associated comorbidities involved chronic inflammatory dermatoses, atopic diseases, autoimmune diseases and mental disorders. Discussion: The review also highlighted evidence gaps, such as the need for validated diagnostic criteria in NHIRD and more research on ocular and systemic comorbidities. Given the significant disease burden of AA, further studies are needed to improve understanding and inform patient care and treatment strategies.