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Vitamin D supplementation to prevent asthma exacerbations: systematic review and meta-analysis of individual participant data
Lancet Respiratory Medicine
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Background: Aggregate data meta-analysis of randomized controlled trials (RCTs) shows that vitamin D supplementation reduces the rate of moderate/severe asthma exacerbations, defined as those requiring treatment with systemic corticosteroids. It is not known whether this effect is restricted to patients with lower baseline vitamin D status. Methods: We conducted a systematic review with one-step and two-step meta-analyses of individual participant data (IPD) from randomised controlled trials adjusting for age, sex, and clustering by study. Sub-group analyses were done to determine whether effects of vitamin D on risk of asthma exacerbation varied according to baseline 25-hydroxyvitamin D (25[OH]D) concentration, age, sex, ethnic / racial origin, body mass index, vitamin D dosing regimen, use of inhaled corticosteroids or study duration. Findings: IPD were sought for eight eligible randomised controlled trials (total 1,078 participants), and obtained for 955/978 (97.6%) participants in seven studies. Vitamin D supplementation reduced the rate of moderate/severe asthma exacerbation among all participants (adjusted Incidence Rate Ratio [aIRR] 0.74, 95% CI 0.56 to 0.97, P=0.03, 955 participants in 7 studies). Sub-group analyses revealed that statistically significant protective effects were seen in participants with baseline 25(OH)D <25 nmol/L (aIRR 0.33, 95% CI 0.11 to 0.98, P=0.046, 92 participants in 3 studies) but not in those with higher baseline 25(OH)D levels (aIRR 0.77, 95% CI 0.58 to 1.03, P=0.08, 764 participants in 6 studies; P for interaction =0.25). P values for interaction were also >0.05 for all other sub-group analyses performed. Interpretation: Vitamin D supplementation reduced the rate of moderate/severe asthma exacerbation overall. We did not find definitive evidence that effects of this intervention differed across sub-groups of patients. Funding: Health Technology Assessment Program, National Institute for Health Research (Reference Number 13/03/25)
AuthorsMARTINEAU, AR; jolliffe, DA; griffiths, CJ; greenberg, L; hooper, RL; camargo, C; kerley, C; jensen, M; mauger, D; stelmach, I;...
- Population Health