Vitamin D supplementation does not reduce COPD exacerbations
MedWire News: High-dose vitamin D supplementation does not reduce the incidence of exacerbations in patients with moderate to very severe chronic obstructive pulmonary disease (COPD), Belgian researchers report.
Wim Janssens and colleagues from University Hospitals Leuven explain that low serum 25-hydroxyvitamin D (25-[OH]D) levels -which reflect vitamin D status - are associated with reduced lung function (measured as the forced expiratory volume in one second [FEV1]), impaired immunologic control, and increased airway inflammation.
Furthermore, the researchers have previously demonstrated that vitamin D deficiency (defined as serum 25-[OH]D levels <20ng/mL), is present in 60% to 75% of patients with severe COPD.
In the present study, Janssens and team investigated whether supplementation with high doses of vitamin D could reduce the incidence of COPD exacerbations in a group of 182 patients with moderate to very severe COPD (FEV1<80% predicted) and a history of recent exacerbations.
The patients were randomly assigned to receive 100,000 IU of vitamin D supplementation (n=91) or placebo (n=91) every 4 weeks for 1 year.
At baseline, both groups had a mean serum 25-(OH)D level of 20 ng/mL. During the study, this increased significantly to 52 ng/mL in the vitamin D group, but only marginally to 22 ng/mL in the placebo group, resulting in a significant mean between-group difference of 30 ng/mL.
During the trial there were 229 exacerbations reported in the vitamin D group and 239 reported in the placebo group.
The researchers observed that the median time to first exacerbation - the primary study outcome - did not differ significantly between the vitamin D and placebo groups, at 84 versus 56 days, which is equivalent to a hazard ratio (HR) of 1.1.
There were also no significant between group differences in exacerbation rates (rate ratio [RR]=0.94), FEV1 (1.22 vs 1.17 L), hospitalization rate (RR=1.13), and the risk for death (HR=0.69).
However, a post-hoc analysis in 30 participants with severe vitamin D deficiency (serum 25-[OH]D<10 ng/mL) at baseline showed a significant 43% reduction in the rate of exacerbations in the vitamin D group compared with the placebo group.
Janssens and co-authors comment that the lack of a therapeutic effect with vitamin D may be due to the fact that most participants presented with severe vitamin D deficiency and were receiving maximum inhalation therapy.
"As all of these treatments are known to reduce exacerbations, any additional effect of vitamin D in addition to regular treatment is probably more difficult to obtain," they write.
They add: "Intervention in the earlier stages of COPD when patients receive fewer medications might therefore be more effective, which is consistent with the idea that such milder stages are also more sensitive to disease modification."
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By Laura Cowen