Lung VITAL: Rationale, design, and baseline characteristics of an ancillary study evaluating the effects of vitamin D and/or marine omega-3 fatty acid supplements on acute exacerbations of chronic respiratory disease, asthma control, pneumonia and lung function in adults

Abstract

Laboratory and observational research studies suggest that vitamin D and marine omega-3 fatty acids may reduce risk for pneumonia, acute exacerbations of respiratory diseases including chronic obstructive lung disease (COPD) or asthma, and decline of lung function, but prevention trials with adequate dosing, adequate power, and adequate time to follow-up are lacking. The ongoing Lung VITAL study is taking advantage of a large clinical trial-the VITamin D and OmegA-3 TriaL (VITAL)--to conduct the first major evaluation of the influences of vitamin D and marine omega-3 fatty acid supplementation on pneumonia risk, respiratory exacerbation episodes, asthma control and lung function in adults. VITAL is a 5-year U.S.-wide randomized, double-blind, placebo-controlled, 2 × 2 factorial trial of supplementation with vitamin D3 ([cholecalciferol], 2000 IU/day) and marine omega-3 FA (Omacor® fish oil, eicosapentaenoic acid [EPA]+docosahexaenoic acid [DHA], 1g/day) for primary prevention of CVD and cancer among men and women, at baseline aged ≥50 and ≥55, respectively, with 5107 African Americans. In a subset of 1973 participants from 11 urban U.S. centers, lung function is measured before and two years after randomization. Yearly follow-up questionnaires assess incident pneumonia in the entire randomized population, and exacerbations of respiratory disease, asthma control and dyspnea in a subpopulation of 4314 randomized participants enriched, as shown in presentation of baseline characteristics, for respiratory disease, respiratory symptoms, and history of cigarette smoking. Self-reported pneumonia hospitalization will be confirmed by medical record review, and exacerbations will be confirmed by Center for Medicare and Medicaid Services data review.

Trial registration: ClinicalTrials.gov NCT01728571.

Keywords: COPD; Lung function; Omega-3 fatty acids; Randomized clinical trial; Respiratory symptoms; Vitamin D.

Fig. 1

Mechanisms by which vitamin D may improve handling of respiratory infections, lung function, or immune modulation, with downstream influences on incident pneumonia, respiratory symptoms and disease progression. Adapted from Manson [27] and Litonjua [60]. ^{, ,}

Fig. 2

Mechanisms by which marine omega-3 fatty acids may reduce inflammation, improve lung function, and reduce exacerbations of asthma or COPD. Adapted from Manson [27] and Wendell [25].

Fig. 3

Odds of symptoms (95% CI) for increasing pack-year history of smoking, compared to never smoking. Models are adjusted for age, height, body-mass index (kg/m²), gender, and race/ethnicity.

Fig. 4

Level of lung function (95% CI) for increasing pack-year history of smoking, compared to never smoking. Models are adjusted for age, height, body-mass index (kg/m²), gender, and race/ethnicity.