Psychiatric Comorbidities in Adult Patients with Atopic Dermatitis: A Nationwide Cohort Study Compared to Melanocytic Naevi

Background/Objectives: Atopic dermatitis (AD) is a chronic inflammatory skin disorder increasingly recognized for its association with psychiatric comorbidities. However, the extent of this association compared to dermatologic controls in Asian populations remains underexplored. We sought to evaluate the prevalence and risk of psychiatric comorbidities in adult patients with AD compared to those with melanocytic naevi using a nationwide population-based cohort. Methods: We conducted a retrospective cohort study utilizing the Korean National Health Insurance Service (NHIS) database, including individuals diagnosed with AD (ICD-10 code L20.0) or melanocytic naevi (ICD-10 code D22, excluding melanoma) between 1 January 2010 and 31 December 2023. Patients were required to have at least five years of diagnostic history and be 25 years or older at the end of the study. Psychiatric comorbidities were identified based on ICD-10 codes. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to compare psychiatric morbidity between groups. Results: Among 1,902,114 individuals (1,813,320 with AD and 88,794 with naevi), psychiatric comorbidities were more prevalent in the AD group (28.2%) compared to the naevi group (27.1%) (adjusted OR 1.04, 95% CI 1.02–1.05). While differences for major depression, bipolar disorder, and personality disorders were not statistically significant, other psychiatric categories suggested significantly higher prevalence in the AD group. Sex-stratified analysis revealed a higher overall psychiatric morbidity in women compared to men; however, the relative risk increase associated with AD was slightly greater in men than in women. Comparison with previous international studies suggests that Korea’s healthcare accessibility and nationwide mental health programs may contribute to the smaller observed difference. Conclusions: This large-scale cohort study highlights a modest but significant association between AD and psychiatric comorbidities in adults. Our findings underscore the importance of integrating mental health assessment into routine dermatologic care for AD patients to improve comprehensive disease management.