Serum 25-Hydroxyvitamin D Level Might Be a Useful Indicator of Disease Severity in Obese Children With Atopic Dermatitis: A Case-Control Study

Objective: To assess the relationship between the severity of atopic dermatitis (AD) in children of varying weight categories and their serum 25-hydroxyvitamin D [25(OH)D] levels. Methods: The study population comprised 899 patients with AD and 854 age- and sex-matched controls. The Mann-Whitney U test and Kruskal-Wallis H tests were used to assess differences between groups, and Spearman correlation analysis was used to test correlation. Results: The 25(OH)D level in the AD group was M ( Q 25 , Q 75 ), 24.0 (19.7, 28.4) ng/mL, which was significantly lower than the control group (26.4 [23.6, 29.9] ng/mL; Z = −3.34, P = 0.001). 25(OH)D levels in children with AD were negatively correlated with body mass index ( r = −0.30, P < 0.001), Severity scoring of Atopic Dermatitis (SCORAD; r = −0.14, P < 0.001), total immunoglobulin E ( r = −0.13, P < 0.001), and eosinophil ( r = −0.08, P = 0.017). There were statistically significant differences in 25(OH)D ( H = 18.46, P < 0.001), total immunoglobulin E ( H = 9.13, P = 0.010), eosinophil ( H = 67.17, P < 0.001), and SCORAD ( H = 10.49, P = 0.005) among groups with different body mass index classification. The 25(OH)D levels were 22.3 (17.5, 27.1) ng/mL in the overweight AD group and 22.3 (17.6, 25.7) ng/mL in the obese AD group, which were significantly lower than those in the normal-weight AD group (24.7 [20.4, 25.5] ng/mL; P = 0.003, P = 0.004). 25(OH)D levels were negatively correlated with SCORAD in obese AD patients ( r = −0.25, P = 0.010). Conclusion: Vitamin D insufficient or deficient is obvious in children AD patients. The 25(OH)D levels in the overweight/obese AD group are significantly lower than those in the normal-weight AD group. Vitamin D level is negatively correlated with SCORAD in obese children with AD.