Rationale: Although vitamin D is well known for its function in calcium homeostasis and bone mineralisation, several studies have shown immunomodulatory effects of vitamin D. Vitamin D deficiency is a common problem in patients with COPD..~Objective: To assess the effect of vitamin D supplementation on exacerbation rate in patients with COPD and a vitamin D deficiency.~Study design: Randomized, multi-center, double-blind, placebo-controlled intervention study.~Study population: 240 patients aged 40 years and older with COPD and a vitamin D deficiency (25-hydroxyvitamin D concentration(25OHD)<50 nmol/l) with a COPD exacerbation. An exacerbation is defined as sustained worsening of respiratory symptoms during 48 hours and requiring oral corticosteroid, antibiotic or combination treatment that was initiated by a physician. Respiratory symptoms include at least one of the Anthonisen criteria (increased dyspnoea, sputum volume or purulence). Patients with a severe vitamin D deficiency (25OHD<15 nmol/l), known osteoporosis and/or use of vitamin D supplementation > 400 IU per day will be excluded.~Intervention: Participants will be randomly allocated to receive vitamin D3 16800 IU or placebo orally once a week during 1 year.~Main study parameters/endpoints: The primary endpoint is exacerbation rate.~Follow-up of the study:~Recruitment of participants is more troublesome than expected due to several reasons, more use of vitamin D supplements, higher 250hydroxyvitamin D levels than anticipated, less suitability due to presence other exclusion criteria.~29/8/2017 total number recruited participants is 119~10/7/2018 closure of recruitment, total number recruited participants is 158
Vitamin D has an immunomodulatory role. the aim of the present study is to assess the effect of vitamin D supplementation on exacerbation rate of COPD patient with a vitamin D deficiency.