Jolliffe DA, et al. - In this study, researchers analyzed data from double-blind, placebo-controlled, randomised controlled trials assessing vitamin D supplementation as a preventive strategy for asthma exacerbations requiring treatment with systemic corticosteroids. Furthermore, it was investigated if impacts of vitamin D on risk of asthma exacerbation varied according to baseline 25-hydroxyvitamin D (25[OH]D) concentration, age, ethnic or racial origin, body-mass index, vitamin D dosing regimen, use of inhaled corticosteroids, or end-study 25(OH)D levels. Findings demonstrated that as a result of vitamin D supplementation, an overall reduction occurred in the rate of asthma exacerbations requiring treatment with systemic corticosteroids. Notably, researchers did not find definitive evidence that effects of this intervention differed across subgroups of patients.