S95 Double-blind Multi-centre Randomised Controlled Trial Of Vitamin D3 Supplementation In Adults With Inhaled Corticosteroid-treated Asthma (vidias)

Abstract

Introduction and objectives Asthma exacerbations are commonly precipitated by viral upper respiratory infections (URI). Vitamin D insufficiency associates with susceptibility to URI in patients with asthma. A recent vitamin D trial in adults with asthma reported a trend towards reduced exacerbation risk in the intervention arm as a secondary outcome. Trials of vitamin D in adults with asthma with incidence of exacerbation and URI as primary outcome are lacking. We therefore conducted a multi‐centre randomised controlled trial of vitamin D3 supplementation in adults with asthma with co‐primary outcomes of severe exacerbation and URI. Methods Two hundred and fifty adults with inhaled corticosteroid (ICS)‐treated asthma were allocated to receive six 2‐monthly oral doses of 3 mg vitamin D3 or placebo over one year. Co‐primary outcomes were time to first severe exacerbation and time to first URI. Sub‐group analyses were performed to determine whether effects of supplementation were modified by baseline vitamin D status or genotype for thirty‐four single nucleotide polymorphisms in eleven vitamin D pathway genes. Results Participants were allocated to vitamin D3 vs. placebo in equal numbers; 82% were vitamin D insufficient at baseline. Vitamin D3 supplementation did not influence time to first severe exacerbation (aHR 1.02, 95% CI 0.69‐1.53, P = 0.91) or time to first URI (aHR 0.87, 95% CI 0.64‐1.16, P = 0.34). The influence of vitamin D3 on co‐primary outcomes was not modified by baseline vitamin D status or genotype. Of 16 pre‐specified secondary outcomes, only one showed a difference between arms: vitamin D supplementation induced a modest improvement in respiratory quality of life as evidenced by a reduction in mean total score for the St George's Respiratory Questionnaire at 2 months (‐3.9 points, p = 0.005), 6 months (‐3.7 points, p = 0.038) and 12 months (‐3.3 points, p = 0.060). Conclusions Vitamin D3 supplementation did not influence time to exacerbation or URI in a population of adults with ICS‐treated asthma with a high prevalence of baseline vitamin D insufficiency.