Effect of vitamin D supplementation on asthma control in patients with vitamin D deficiency: the ACVID randomised clinical trial

Background The relationship between asthma and vitamin D deficiency has been known for some time. However, interventional studies conducted in this regard have shown conflicting results. Objective To evaluate the efficacy of vitamin D supplementation in asthmatic patients in improving the degree of control of asthma. Methods Randomised, triple-blind, placebo-controlled, parallel-group study in adult asthmatic patients with serum 25-hydroxyvitamin-D-3 <30 ng/mL. The intervention group received oral supplementation with 16 000 IU of calcifediol per week, and the control group had placebo added to their usual asthma treatment. The study period was 6 months. The primary endpoint was the degree of asthma control as determined by the asthma control test (ACT). Secondary endpoints included quality of life measured using the mini Asthma Quality of Life Questionnaire, the number of asthma attacks, oral corticosteroid cycles, the dose of inhaled corticosteroids, number of emergency visits, unscheduled consultations with the primary care physician and hospitalisations for asthma. Results One hundred and twelve patients were randomised (mean age 55 years, with 87 (78%) being women). Of the 112 patients, 106 (95%) completed the trial. Half the patients (56) were assigned to the intervention group and the other half to the control group. A statistically significant clinical improvement was observed in the intervention group (+3.09) compared with the control group (-0.57) (difference 3.66 (95% CI 0.89 to 5.43); p<0.001) as measured using ACT scores. Among the secondary endpoints, a significant improvement in the quality of life was found in the intervention group (5.34), compared with the control group (4.64) (difference 0.7 (95% CI 0.15 to 1.25); p=0.01). Conclusion Among adults with asthma and vitamin D deficiency, supplementation with weekly oral calcifediol compared with placebo improved asthma control over 6 months. Further research is needed to assess long-term efficacy and safety. Trial registration number NCT02805907.