The Epidemiology of Atopic Dermatitis among Adults and Adolescents with Alopecia Areata in the United States.

This study evaluated the prevalence, incidence, and relative risk of comorbid atopic dermatitis (AD) among patients with alopecia areata (AA) using data from the Merative MarketScan Research Databases. Eligible patients had ≥1 inpatient or ≥2 outpatient claims for AA between January 1, 2017 and October 31, 2023; were aged ≥12 years; and were continuously enrolled during the ≥5-year baseline period through the 6-month follow-up period; index date was the earliest date of AA diagnosis. AD prevalence (%) and incidence (cases per 1000 person-years) among patients with AA are reported and stratified by disease severity; a subgroup analysis was performed among adolescents (aged 12-17 years). Adjusted hazard ratios for being diagnosed with AD are reported for patients with moderate-to-severe versus those with mild AA. Prevalence of AD among patients with AA at baseline was 3.2% (overall prevalence in database: 12.1%), with most having moderate-to-severe AD; prevalence was higher among adolescents with AA (7.6%). Incidence of AD increased with AA disease severity, regardless of age. Those with moderate-to-severe AA had 78% higher risk of being diagnosed with AD than those with mild disease. Dermatologist-diagnosed patients had higher rates of comorbid AD regardless of AA severity. These data demonstrate the importance of increased risk of comorbid AD when making treatment decisions for patients with AA.