Epidemiological, clinical and economic burden of alopecia areata in Spain: a real-world retrospective study. The PETALO study.

Alopecia areata (AA) is a chronic autoimmune disease that causes non-scarring hair loss. Data are lacking on the epidemiology and clinical and economic burden of AA in Spain. To estimate the prevalence and incidence of AA in Spain and describe sociodemographic and clinical characteristics, treatment patterns, healthcare resource utilization (HCRU) and associated costs. This was an observational, retrospective, descriptive study based on the Health Improvement Network (THIN®) database (Cegedim Health Data, Spain). Patients with ICD9-Code 704.01 for AA, registered between 2014 and 2021, were identified. Prevalence (%) and incidence rates per 1,000 patient-years (IR) of AA were calculated and clinical characteristics, treatment characteristics and HCRU/costs were assessed. A total of 5,488 patients with AA were identified. The point prevalence of AA in 2021 was 0.44 (95% confidence interval [CI]: 0.43-0.45) overall, 0.48 (0.47-0.49) in adults, and 0.23 (0.21-0.26) in children ≤12 years. The 2021 IR for AA in adults was 0.55 (0.51-0.60). Of 3,351 adults with AA, 53.4% were female, mean (standard deviation [SD]) age was 43.1 (14.7) years, and 41.6% experienced comorbidities. Among adults, 2.7% used systemic treatment (0.5% immunosuppressants, 2.5% oral corticosteroids, 0.3% both). Laboratory tests and health care professional visits were the principal drivers of cost, which was €821.2 (1065.6)/patient in the first year after diagnosis. The epidemiology of AA in Spain is comparable with that reported for other countries, being more prevalent among adults. There is a significant burden of comorbidities and cost for patients, with limited use of systemic treatments, suggesting an unmet treatment need in this population.