October 12, 2017
2 min read

Vitamin D prevents severe asthma exacerbations

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Vitamin D supplementation reduced the rate of asthma exacerbations requiring treatment with systemic corticosteroids, as well as exacerbations requiring hospitalizations, according to findings published in the Lancet Respiratory Medicine.

“A previous aggregate data meta-analysis of randomized controlled trials showed that vitamin D supplementation reduces the rate of asthma exacerbations requiring treatment with systemic corticosteroids,” David A. Jolliffe, PhD, from Barts and The London School of Medicine and Dentistry, and colleagues wrote. “Whether this effect is restricted to patients with low baseline vitamin D status is unknown.”

Jolliffe and colleagues performed a systematic review and one-step and two-step meta-analysis of eight eligible double-blind, placebo-controlled, randomized controlled trials that evaluated the effects of vitamin D3 or vitamin D2 supplementation in patients with asthma experiencing asthma exacerbations. From these eight trials, researchers sought individual participant data and obtained it for seven studies, totaling 955 participants.

The researchers aimed to determine the incidence of asthma exacerbation that required systemic corticosteroid treatment, while adjusting for age and sex and clustering by study. They also conducted subgroup analyses to determine if there was variation in the effects of vitamin D on asthma exacerbation risk by baseline 25-hydroxyvitamin D (25[OH]D) concentration, age, ethnic or racial origin, BMI, vitamin D dosing regimen, use of inhaled corticosteroids or end-study 25(OH)D levels.

High-quality evidence revealed that among all participants, the rate of asthma exacerbation requiring treatment with systemic corticosteroids declined 30% from 0.43 events per person per year to 0.30 as a result of vitamin D supplementation (adjusted incidence rate ratio [aIRR] = 0.74; 95% CI, 0.56-0.97). Vitamin D supplementation reduced the incidence of at least one asthma exacerbation requiring ED attendance or hospital admission or both (adjusted OR = 0.46; 95% CI, 0.24-0.91). The proportion of participants with at least one exacerbation and time to first exacerbation did not significantly differ between vitamin D and placebo groups.

Subgroup analyses of three studies (n = 92) showed that in participants with baseline 25(OH)D of less than 25 nmol/L, there was a statistically significant reduction in the rate of asthma exacerbations requiring treatment with systemic corticosteroids (aIRR = 0.33; 95% CI, 0.11-0.98). However, this reduction in exacerbation rate was not seen in participants with higher baseline 25(OH)D levels (aIRR = 0.77; 95% CI, 0.58-1.03), according to moderate-quality evidence from six studies, totaling 764 participants. The effects of vitamin D supplementation did not differ across subgroups.

Six studies were considered as having low risk for bias, while the risk was unclear in one study. There was no evidence of heterogeneity of the vitamin D effect (I² = 0.0; P = 0.56), according to the two-step meta-analysis. Data indicated that vitamin D was safe and the rate of severe adverse events was similar between participants taking vitamin D and those taking placebo.

“These results add to the ever growing body of evidence that vitamin D can support immune function as well as bone health... Vitamin D is safe to take and relatively inexpensive, so supplementation represents a potentially cost-effective strategy to reduce this problem,” Adrian R. Martineau, PhD, lead researcher from Barts and The London School of Medicine and Dentistry, said in a press release. – by Alaina Tedesco

Disclosures: The authors report no relevant financial disclosures.