Serum 25-hydroxyvitamin D and adult-onset atopic dermatitis: insights from two large national cohorts.

Background

The incidence rate of adult-onset atopic dermatitis (AOAD) is rising. There is still limited evidence regarding the association between serum 25-hydroxyvitamin D (25(OH)D) and the risk of AOAD.

Objective

This study determined the extent to which a lower level of serum 25(OH)D is associated with the risk of AOAD in two large, population-based cohorts.

Methods

We included 6340 participants from the Korean National Health and Nutrition Examination Survey (KNHANES) and 229 260 participants from the UK Biobank cohort. The multivariable logistic regression analyses and multivariable Cox proportional hazards regression were performed to estimate odds ratios (ORs), hazard ratios (HRs) and 95% confidence intervals (CIs) of serum 25(OH)D in relation to incident AOAD.

Results

In the cross-sectional analysis, individuals with 25(OH)D deficiency or insufficiency had significantly higher odds of prevalent AOAD compared to those with sufficient levels (deficiency: OR, 1.80 [95% CI, 1.01-3.02]; insufficiency: OR, 1.61 [1.00-2.59]). In the prospective UK Biobank cohort, lower 25(OH)D status at the baseline was associated with an increased risk of incident AOAD during follow-up (deficiency: HR, 1.20 [1.04-1.38]; insufficiency: HR, 1.31 [1.09-1.58]). Despite differences in study design and outcome ascertainment, both cohorts showed a linear inverse relationship between serum 25(OH)D levels and AOAD risk.

Conclusions

Our findings revealed that elevated levels of serum 25(OH)D were robustly associated with a decreased risk of AOAD. These results hold considerable public health implications, indicating that the serum 25(OH)D may offer a practical and efficient means of detecting high-risk individuals and informing tailored intervention strategies.