Abstract
BackgroundVitamin D is well known for its function in calcium homeostasis and bone mineralisation, but is increasingly studied for its potential immunomodulatory properties. Vitamin D deficiency is a common problem in patients with COPD. Previous studies have not demonstrated a beneficial effect of vitamin D on exacerbation rate in COPD patients. However, subgroup analyses suggested protective effects in vitamin D deficient patients. Our objective is to assess the effect of vitamin D supplementation on exacerbation rate specifically in vitamin D deficient COPD patients.Methods/DesignWe will perform a randomised, multi-center, double-blind, placebo-controlled intervention study. The study population consists of 240 COPD patients aged 40 years and older with vitamin D deficiency (25-hydroxyvitamin D concentration < 50 nmol/L). Participants will be recruited after an exacerbation and will be randomly allocated in a 1:1 ratio to receive vitamin D3 16800 IU or placebo orally once a week during 1 year. Participants will receive a diary card to register the incidence of exacerbations and changes in medication during the study period. Visits will be performed at baseline, at 6 months and at 12 months after randomisation. Participants will undergo spirometry, measurement of total lung capacity and assessment of maximal respiratory mouth pressure. Several physical performance and hand grip strength tests will be performed, questionnaires on quality of life and physical activity will be filled in, a nasal secretion sample and swab will be obtained and blood samples will be taken. The primary outcome will be exacerbation rate.DiscussionThis study will be the first RCT aimed at the effects of vitamin D supplementation on exacerbation rate in vitamin D deficient COPD patients. Also, in contrast to earlier studies that used infrequent dosing regimens, our trial will study effects of a weekly dose of vitamin D supplementation. Secondly, the immunomodulatory effects of vitamin D on host immune response of COPD patients and underlying mechanisms will be studied. Finally, the effects on physical functioning will be examined.Trial registrationThis trial is registered in ClinicalTrials.gov, ID number NCT02122627. Date of Registration April 2014.
Highlights
Chronic obstructive pulmonary disease (COPD) is characterized by a persistent airflow limitation and an abnormal inflammatory response of the airways
This study will be the first RCT aimed at the effects of vitamin D supplementation on exacerbation rate in vitamin D deficient COPD patients
Vitamin D deficiency is highly prevalent in patients with COPD [3, 4]
Summary
Chronic obstructive pulmonary disease (COPD) is characterized by a persistent airflow limitation and an abnormal inflammatory response of the airways. The discovery of the presence of vitamin D receptors (VDR) in many other cells, such as monocytes, macrophages, muscle cells and endothelial cells, has elicited hypotheses of direct vitamin D effects on these cells. These hypotheses are further strengthened by local 25-hydroxyvitamin D-1-alpha-hydroxylase activity, which converts the inactive 25-hydroxyvitamin D (25(OH)D) to the active 1,25-dihydroxyvitamin D (1,25(OH)2D), in many of these cells. The presence of vitamin D receptors on immune cells [5] and the high prevalence of vitamin D deficiency among COPD patients has given rise to the hypothesis that vitamin D might have a potential effect in preventing exacerbations in patients with COPD [6]. Our objective is to assess the effect of vitamin D supplementation on exacerbation rate in vitamin D deficient COPD patients
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