This study will determine whether vitamin D3 prevents severe asthma attacks in children who have a serum vitamin D (25(OH)D) level \<30 ng/ml and who are being treated with inhaled corticosteroids for asthma. Half the participants will receive vitamin D3 at a dose of 4,000 IU/day, and the other half will receive placebo.
Results from experimental studies, observational studies, two small trials, and a recent meta-analysis suggest that vitamin D reduces the risk of severe asthma exacerbations, and that this protective effect may be due to immune modulation of viral illnesses and/or increased response to inhaled corticosteroids (ICS). On the basis of those findings, the investigators hypothesize that vitamin D reduces the incidence of severe asthma exacerbations in high-risk school-aged children who have a serum vitamin D level \<30 ng/ml and who are being treated with ICS for persistent asthma. The investigators further hypothesize that this protective effect results from reduced incidence of common viral illnesses or enhanced response to ICS. These hypotheses will be tested in a 48-week randomized double-masked placebo-controlled trial of vitamin D3 supplementation to prevent severe asthma exacerbations in 400 children aged 6 to 16 years who have vitamin D insufficiency or deficiency (a serum 25(OH)D \<30 ng/ml) and experienced a severe exacerbation in the prior year (a marker of high risk for subsequent events), and who (after a run-in period) are well controlled on medium-dose inhaled corticosteroids. Our primary aim will determine whether vitamin D3 (4,000 IU/day) reduces the risk of severe asthma exacerbations (our primary outcome) in participating children. Secondary aims will determine the efficacy of vitamin D3 supplementation in: 1) preventing severe asthma exacerbations due to viral infections, 2) reducing the daily and average cumulative dose of inhaled corticosteroids. Study participation involves 8-9 visits, with each visit lasting between 30-90 minutes. Participation requires completion of study questionnaires, spirometry (breathing tests), and collection of blood samples (to measure vitamin D levels) and urine samples (to measure urinary calcium/creatinine ratios) at some study visits. Since the start of the study, vitamin D levels and urinary calcium/creatinine ratios have been simultaneously measured, to monitor for both vitamin D toxicity and high risk of severe vitamin D deficiency or rickets, which (should they occur) would be managed by a pediatric endocrinologist or a pediatric nephrologist, as appropriate. All safety data for the study is regularly reviewed by a Data Safety Monitoring Board appointed by the National Heart, Lung and Blood Institute, as well as by the Institutional Review Board of each participating institution. Total study participation will last about one year.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
192
The vitamin D3 will be in oral gel cap form and contain 4000 International Units (IU) of cholecalciferol per gel cap.
The placebo is a gel cap that is indistinguishable from the vitamin D3 gel cap.
University of California - San Francisco
San Francisco, California, United States
National Jewish Health
Denver, Colorado, United States
Boston Children's Hospital
Boston, Massachusetts, United States
Saint Louis Children's Hospital
St Louis, Missouri, United States
Days to a Severe Asthma Exacerbation
A severe asthma exacerbation is defined as an exacerbation that meets either of these criteria: 1) Use of systemic corticosteroids (tablets, suspension, or injection), or an increase from a stable maintenance dose, for at least 3 days OR 2) A hospitalization or ER visit because of asthma, requiring systemic corticosteroids.
Time frame: 48 weeks
Days to Viral-induced Severe Exacerbation
A severe viral asthma exacerbation is defined as a severe asthma exacerbation \[defined as an exacerbation that meets either of these criteria: 1) Use of systemic corticosteroids (tablets, suspension, or injection), or an increase from a stable maintenance dose, for at least 3 days OR 2) A hospitalization or ER visit because of asthma, requiring systemic corticosteroids\] along with a positive respiratory viral panel from a nasal blow collected within 72 hours of the exacerbation.
Time frame: 48 weeks
Proportion of Participants in Whom Fluticasone Dose Was Halved at Visit 6
In the absence of moderate or severe asthma exacerbations, participants may have their dose of inhaled corticosteroids (ICS) reduced by 50% if the following criteria are met at visit 6 (halfway through the Trial Phase): * Asthma Control Test (ACT) score greater than 19 * Both pre-bronchodilator FEV1 and FEV1/FVC ≥80% of predicted * Use of ≤4 puffs of a rescue inhaler per week * ≤1 day per month with asthma symptoms preventing full participation in usual daily activities * Clinician's judgment regarding adequate asthma control
Time frame: 24 weeks
Average Cumulative Prescribed Dose of ICS at the End of the Trial
The average cumulative dose of inhaled corticosteroids (ICS) during the study period
Time frame: 48 weeks
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Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, United States
Rainbow Babies and Children's Hospital
Cleveland, Ohio, United States
Children's Hospital of Pittsburgh of UPMC
Pittsburgh, Pennsylvania, United States