Principal objective: To define the therapeutic effect of Vitamin D in the chronic maintenance treatment of COPD by means of a prospective randomized placebo-controlled double blind study of 182 patients with a follow-up of at least one year. Primary endpoint is the median time to next exacerbation. Secondary endpoints are total number of exacerbations per group, number of exacerbations per patient per year, percentage of patients with one or more exacerbations per year, days of antibiotics and oral steroids, quality of life, FEV1, muscle force and survival.
Other objectives: First, to investigate the role of local and systemic levels of 25-OHD and 1,25-(OH)2D on the intensity and prevalence of bacterial colonisation, inflammatory markers, proteases and markers of oxidative stress in induced sputa and exhaled air. Second, to explore whether correction of Vitamin D deficiency by the oral supplementation of Vitamin D triggers the VDR-mediated cathelicidin pathway and increases local or systemic concentrations of the natural antimicrobial polypeptide cathelicidin with enhanced eradication of bacteria.
