Abstract
Observational studies have shown that low vitamin D levels are linked to worse lung function and poor asthma control in children with asthma. We hypothesized that vitamin D supplementation would improve function, disease control, and quality of life in children with asthma (ages 6–16 years) and vitamin D levels below 30 ng/ml. We tested this hypothesis in a secondary analysis of data from the Vitamin D Kids Asthma Study (VDKA), a randomized, double-blind, parallel, placebo-controlled clinical trial. Each participant in the VDKA was randomly assigned to either daily placebo capsules or daily vitamin D3 (4,000 IU) plus low-dose inhaled fluticasone propionate. Of the 192 randomized participants, 176 were included in the analysis of change in percent predicted lung function measures (FEV(1), FVC, and FEV(1)/FVC) and asthma control scores. Of these 176 participants, 94 were also included in the analysis of change in asthma-related quality of life scores, as they were 10 years and older. Linear regression was used for the multivariable analysis of vitamin D supplementation and each outcome, which was adjusted for study site, race, sex, and time in the study. In this analysis, vitamin D supplementation was not significantly associated with change in any outcome (lung function measures, asthma control, or asthma-related quality of life) between the randomization and exit visits. Our results do not support recommending vitamin D supplementation to improve lung function, asthma control, or asthma-related quality of life in children with asthma and vitamin D levels below 30 ng/ml. Trial registration: clinicaltrials.gov identifier: NCT02687815