Direct infant ultraviolet light exposure is associated with eczema and immune development: a critical appraisal

Abstract

Summary Aim Rueter et al. aimed to ‘determine the effects of early postnatal vitamin D supplementation on infant eczema and immune development’. Setting and design This was a double‐blind randomized placebo‐controlled trial with an additional nonrandomized exploratory analysis on the effects of ultraviolet (UV) exposure led from a hospital setting. Study exposure Vitamin D (400 iU daily) drops or placebo drops (coconut and palm kernel oil) were allocated randomly to 195 infants born to families with a first‐degree relative with atopic disease. Eighty‐six of these infants were allocated personal UV dosimeters in a nonrandomized fashion to measure UV light (290–380 nm) exposure until 3 months of age. Outcomes Eczema and wheeze were assessed at 3 and 6 months, and 25 immune function markers were assessed at 6 months of age. Infant vitamin D levels and immune functions were measured at 6 months of age. Results Although vitamin D levels were significantly greater in infants in the intervention group than in those in the placebo group at 3 and 6 months of age, there was no difference in eczema between groups at either time point (10·0% vs. 6·7% at 3 months and 21·8 vs. 19·3% at 6 months for the vitamin D and placebo groups, respectively). In the subset of infants given a dosimeter, those with eczema had less UV light exposure (median 555 J m−2) than infants who did not develop eczema (median 998 J m−2). Across the 25 immune functions, UV light exposure was inversely correlated with interleukin‐2, granulocyte macrophage colony‐stimulating factor and eotaxin production by Toll‐like receptor ligands. Conclusions Vitamin D supplementation in high‐risk infants increased vitamin D levels but did not reduce eczema. Exploratory post‐hoc analyses in a nonrandomized subset showed an association between greater direct UV light exposure and reduction of eczema. The authors claim that their ‘findings indicate that UV light exposure appears more beneficial than vitamin D supplementation as an allergy prevention strategy in early life’.

Modifiable risk factors in paediatric atopic dermatitis: is the sun finally shining?

“…In a post‐hoc analysis, children with high cumulative UVR exposure in the first 3 months of life had a strongly reduced risk of eczema, indicating beneficial effects of the sun that were not explained by vitamin D . This finding is indeed consistent with other studies, but in the comprehensive and detailed analysis of this study, Maslin et al . argue that multiple explanations exist for the observed association including bias and confounding.…”

“…In this issue of the BJD , Maslin et al . give a critical appraisal of a recent RCT examining the effects of vitamin D supplementation in infants .…”

Avoidable research waste in dermatology: what are the solutions?

“…Funders have a key role to play here by not giving out ‘grants’ but, like the NIHR HTA Programme, making it a contracting requirement for the study to be registered and keeping back say 10% of the award until full publication is complete. Perhaps the greatest potential to reduce bias rests with journal readers to call out research waste when they see it, for example through critically appraised topics, 5 letters to the editor 6 or just rapid responses.…”