699 - Prevalence and incidence of atopic dermatitis in patients with alopecia areata in the United States: a population-based study
Authors: Mostaghimi Arash , Armstrong April W , Grada Ayman , Soliman Ahmed M , Li Chao , C Bristow Claire , Lipiszko Dawid , Silverberg Jonathan I , Issa Naiem T , Bunick Christopher G 
Published: August 2024

Abstract

Introduction/Background
Studies have shown that patients with vs without alopecia areata (AA) have a higher risk of developing atopic dermatitis (AD). However, the real-world prevalence and incidence of moderate-to-severe AD in patients with AA are not well characterized.

Objectives
To assess the real-world prevalence and incidence of comorbid AD among patients with AA using data from a US administrative claims database.

Methods
This retrospective analysis evaluated claims from the Merative Marketscan Commercial Claims and Encounters database. Eligible patients were aged ≥12 years at index date (first AA diagnosis), received an AA diagnosis (≥1 inpatient encounter or ≥2 outpatient encounters/claims based on International Classification of Diseases, Clinical Modification, 10th Revision [ICD-10-CM]: L63.x or 9th Revision [ICD-9-CM]: 704.01) between 01/01/2017–07/31/2023, and had continuous plan enrollment for 5 years prior to index. AA disease severity was evaluated during the 6-month follow-up period post-index date. Patients were considered to have moderate-to-severe AA if they were diagnosed with alopecia universalis (ICD-10-CM: L63.1) or alopecia totalis (ICD-10-CM: L63.0) or if they received prescriptions for any systemic immunomodulators, oral corticosteroids, nonsteroidal systemic agents, or phototherapy within 6 months post-index date. Very severe AA (subset of moderate-to-severe AA) was defined by a diagnosis of alopecia universalis (ICD-10-CM: L63.1) or alopecia totalis (ICD-10-CM: L63.0). AD was defined as ≥1 inpatient or ≥2 outpatient claims with diagnosis codes for AD (ICD-10-CM L20.x) or other AD-related conditions (ICD-9-CM 691.8). Moderate-to-severe AD was defined per the AD criteria plus claims indicating 1 of the following: ≥1 dispensing of dupilumab; ≥2 dispensing of high-potency topical corticosteroids or systemic immunosuppressants; or ≥3 dispensing of medium potency topical corticosteroids, topical tacrolimus, phototherapy, or oral/parenteral corticosteroids. AD prevalence was assessed during the 5 years pre-index period; prevalence was also assessed over a longer duration and included those with ≥1 AD diagnosis from 01/01/2007–index. AD incidence was assessed from the 7th month after the AA index date through the time of AD diagnosis or end of continuous enrollment. Relative risk for developing AD comorbidity among patients with AA was evaluated using Cox proportional hazards model, controlling for age, sex, obesity, Charlson Comorbidity Index (CCI), and geographic region.

Results
Of 429,903 patients identified with AA in the database, 10,863 met eligibility criteria and 9507 completed ≥6 months of follow-up post-index date (mild AA, n=7087; moderate-to-severe AA, n=2420; very severe AA, n=491). The 1-year period prevalence of AA in the US was 0.16% in 2022. Among the 10,863 eligible patients, 63.0% were female, the mean (SD) age was 40.4 (15.1) years, and the mean (SD) CCI was 0.7 (1.2). Among all eligible patients with AA (n=10,863), the prevalence (within 5 years pre-index date) was 3.1% for any AD and 2.3% for moderate-to-severe AD. Among patients with moderate-to-severe AA (n=2420), the prevalence was 4.8% for any AD and 4.2% for moderate-to-severe AD. The prevalence of any AD any time prior to index among all eligible patients with AA and moderate-to-severe AA was 11.9% and 14.6%, respectively. AD incidence at follow-up was 4 per 1000 person-years in patients with mild AA, 7 per 1000 person-years for moderate-to-severe AA, and 6 per 1000 person-years for very severe AA. Mean (SD) time to AD diagnosis after AA index date was 2.1 (1.7) years for patients with mild AA, 2.0 (1.7) years for moderate-to-severe AA, and 2.0 (1.7) years for very severe AA. Risk of developing AD was greater in patients with moderate-to-severe vs mild AA (adjusted hazard ratio 1.63 [95% CI 1.01, 2.64]).

Conclusions
Patients with moderate-to-severe vs mild AA had higher prevalence and incidence of AD comorbidity and higher prevalence of moderate-to-severe AD.