Vitamin D Supplementation Does Not Improve Persistent Asthma Outcomes

Erick Forno, MD, MPH

A new study found that vitamin D₃ supplementation did not significantly improve the time to severe asthma exacerbation among children with persistent asthma and low vitamin D levels.

A team led by Erick Forno, MD, MPH, Department of Pediatrics, University of Pittsburgh, assessed whether vitamin D supplementation reduced time to severe asthma exacerbation in high-risk children aged 6-16 years and with serum vitamin D levels <30 ng/mL and ≥10 ng/mL.

In the randomized, double-blind, placebo-controlled study—known as The Vitamin D to Prevent Severe Asthma Exacerbations (VDKA)—investigators enrolled a total of 192 participants (mean age, 9.8 years; 77 girls), of which 180 completed the trial.

Participants were randomized 1:1 to receive either vitamin D₃ (4000 IU/d) or placebo for 48 weeks. Both groups were additionally treated with twice-daily doses of inhaled fluticasone propionate (6-11 years: 88 μg; ≥12 years: 110 μg).

During the trial, vitamin D levels in all participants were assessed in-person at baseline, then weeks 16, 32, and 48.

The primary outcome sought by the investigators was time to a severe asthma exacerbation. Secondary outcomes included time to a viral-induced severe exacerbation, the proportion of patients who experienced a reduction in corticosteroid reduction, and the cumulative dose of fluticasone dose by the end of the trial.

Results from the study showed that 36 vitamin-treated participants had 1 or more severe exacerbations—versus 33 in the placebo group.

For the vitamin D treatment group, the mean time to exacerbation was 240 days compared with 253 days for the placebo group (mean group difference: -13.1; 95% CI, -42.6 to 16.4).

The investigators noted that the hazard ratio (HR) was 1.13 (95% CI; 0.69-1.8; P = .63).

The mean number of days to first viral-induced severe exacerbation for the vitamin D₃ and placebo groups was 272 and 281, respectively (-9.1 days; 95% CI, -35.5 to 17.2).

The adjusted HR was 1.32 (95% CI, 0.63-2.75; P = .46).

Additionally, during the midpoint of the trial, 28 (31%) vitamin-treated patients had a reduction of inhaled corticosteroid use, versus 29 (32%) in the placebo group (-1.1%; 95% CI, -14.6 to 12.4).

There was no difference in cumulative fluticasone dose reduction between the groups. (59.6 mg vs 55.2 mg, respectively [4.41 mg; 95% CI, -0.99 to 9.80]).

And finally, they reported that the rate of serious adverse events were similar between the groups.

Forno and colleagues acknowledged that the rates of severe asthma exacerbation in both the vitamin D₃ (37.5%) and placebo (34.4%) group were lower than they excepted; furthermore, the lack of power in the study limited their ability to assess whether this small difference was statistically significant.

“The findings do not support the use of vitamin D₃ supplementation to prevent severe asthma exacerbations in this group of patients,” they concluded.

The study, “Effect of Vitamin D₃ Supplementation on Severe Asthma Exacerbations in Children with Asthma and Low Vitamin D Levels: The VDKA Randomized Clinical Trial” was published online in JAMA.