[Atopic dermatitis severity and vitamin D concentration: a cross-sectional study]

Contradictory findings have recently been published on the association between atopic dermatitis (AD) severity and vitamin D deficiency. The aim of this study was to examine the correlation between 25-hydroxyvitamin D (25(OH)D) concentration and AD severity.

A cross-sectional study was conducted from June 2011 to March 2013 in dermatology departments in adults and children with a diagnosis of AD. The severity of AD was assessed using the SCORAD and PO-SCORAD indexes and serum 25(OH)D concentrations were determined for all patients.

Sixty patients were included: 30 with severe AD and 30 with mild-to-moderate AD. The 25(OH)D concentration was lower in patients with severe AD than in patients with mild-to-moderate AD (15.9 ± 8.3 ng/mL vs. 21.5 ± 8.2 ng/mL; P=0.01). There was a negative correlation between 25(OH)D concentration and respectively, SCORAD (r=-0.47; P<0.001) and PO-SCORAD (r=-0.4; P=0.004) values. The correlation between 25(OH)D concentrations and SCORAD values remained valid after adjustment for age, phototype and season.

This study demonstrated an association between vitamin D deficiency and AD severity but showed no causal link between these variables. Confounding variables such as sun exposure and socioeconomic status were not recorded. A large-sale, comparative interventional study could confirm a real link between these two variables.