ABSTRACT
Aims: To investigate the impact of supplemental vitamin D on pulmonary function in patients with stable chronic obstructive pulmonary disease (COPD). Study Design: Case-control study Place and Duration of Study: Department internal medicine, Rouhani hospital, Babol university of medical sciences, Babol, Iran. Over six months from September 2011 through February 2012 Methodology: Patients with COPD allocated to the treatment or control group intermittently. Thirty patients in the treatment group received 50.000 IU oral cholecalciferol weekly for two months plus routine treatment and 28 patients who served as controls received only their usual medications. The serum 25-hydroxyvitamin D (25-OHD) and FEV1% was measured at baseline and two months later. The primary objective was to determine treatment response defined as 5% or greater increase from baseline in FEV1% and the secondary objective was to determine the association between vitamin D supplementation and treatment response. In statistical analysis Spearman's correlation coefficient was used to determine correlation and logistic regression analysis with calculation of odds ratio (OR) was used to determine association. Results: Mean age of the patients and controls was 67.1±10.5 years and 66.±12.2 years respectively (P=0.83).Thirteen patients (43.3%) versus 3 (10.7%) controls responded to treatment (P=0.009). Treatment response was positively correlated with mean serum 25- OHD changes from baseline (Spearman's correlation coefficient = 0.358, P=0.026). Mean 25-OHD change from baseline in the responders was significantly higher than in no responders (P = 0.031). Mean 25-OHD changes were positively correlated with FEV1% (P = 0.013).Vitamin D supplementation increased the treatment response by OR = 6.37 (95% CI, 1.57-25.8). After adjustment for inhaled bronchodilator, corticosteroid therapy, age, weight, smoking, ESR and CRP the odds of treatment response in vitamin D group increased to 17.1 (95%CI, 2.39-122, P= 0.005). Conclusion: The findings of this study indicate that, two months vitamin D supplement to the drug regimen of COPD confers small pulmonary function improvement as compared with controls and justify serum 25-OHD measurement in COPD. Raising serum 25-OHD to sufficient levels with longer duration of treatment may exert further benefits.