Lifetime Atopic Dermatitis is Associated With Risk of Autoimmune Thyroid Disease: Evidence From a Nationwide Study.

The association between atopic dermatitis (AD) and autoimmune thyroid disease (AITD) has received increasing attention. We investigated the association between AD and the risk of AITD in the Korean adult population. The medical data from 5,410 individuals aged ≥ 19 years from the Korea National Health and Nutrition Examination Survey 2013-2015 were categorized into 2 groups: (1) the thyroid dysfunction group (if they met the criteria of overt hyperthyroidism or overt hypothyroidism) and (2) the anti-thyroid peroxidase antibody (anti-TPO Ab)-positive group. Thyroid dysfunction and anti-TPO Ab positivity were each regarded as surrogate markers for the risk of AITD. The association between AD and the risk of AITD was investigated using multivariable logistic regression analysis to obtain the adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Age-stratified analyses were performed to assess the AD-conferred risks in each age group. Among 5,410 subjects (mean age: 44 years; 51% male), the prevalence of AD, thyroid dysfunction, and anti-TPO Ab positivity was 3.5%, 1.0%, and 6.4%, respectively. Individuals with AD had a higher tendency of having thyroid dysfunction (aOR,1.65; 95% CI, 0.44-6.23) and anti-TPO Ab positivity (aOR, 1.40; 95% CI, 0.73-2.70); however, none of the associations reached statistical significance in this analysis. Nevertheless, in the young adult group (aged 19-39 years), a statistically significant association between AD and thyroid dysfunction (aOR, 5.86; 95% CI, 1.51-22.67) and a marginally significant association between AD and anti-TPO Ab positivity (aOR, 2.05; 95% CI 0.91-4.65; P = 0.08) were found. Among older adults (aged ≥ 40 years), no statistically significant associations were observed for thyroid dysfunction (aOR, 0.41; 95% CI, 0.05-3.30) or anti-TPO Ab positivity (aOR, 1.00; 95% CI, 0.32-3.12). This suggests a relationship between AD and the risk of AITD, highlighting the need to consider comorbid thyroid disease in young adults with AD.