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

Background: 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. Objectives: 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. Materials & Methods: This was an observational, retrospective, descriptive study based on the Health Improvement Network (THIN (R)) 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. Results: 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 <euro>821.2 (1065.6)/patient in the first year after diagnosis. Conclusion: 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.