The efficacy of vitamin D therapy for patients with COPD: a meta-analysis of randomized controlled trials

BACKGROUND: Many studies have demonstrated that vitamin D has clinical benefits when used to treat patients with chronic obstructive pulmonary disease (COPD). However, most of these studies have insufficient samples or inconsistent results. The aim of this meta-analysis was to evaluate the effects of vitamin D therapy in patients with COPD. METHODS: We performed an electronic literature search of the databases PubMed, China National Knowledge Internet (CNKI), Embase, Web of Science and Wanfang Data. Meta-analysis was carried out by Review Manager Version 5.3 (Revman 5.3), and standardized mean difference (SMD) and mean difference (MD) were used to assess the efficacy of vitamin D therapy in patients with COPD. RESULTS: A total of 25 articles involving 2,670 participants were included in this study. The overall results showed a statistical significance of vitamin D therapy in patients with COPD on forced expiratory volume in 1 second (FEV1) (SMD: 1.21, 95% CI: 0.76-1.66, P<0.01), FEV1/FVC (SMD: 1.07, 95% CI: 0.56-1.58, P<0.01), Exacerbations (SMD: 0.39, 95% CI: 0.23-0.64, P<0.01), Sputum volume (SMD: -6.02, 95% CI: -8.25 to 3.79, P<0.01), 6-minute walk distance (6MWD) (MD: 8.82, 95% CI: 1.67-15.98, P=0.02) and COPD assessment test (CAT) score (SMD: -1.19, 95% CI: -1.74 to 0.63, P<0.01). CONCLUSIONS: Our analysis indicated that vitamin D used in patients with COPD could improve the lung function (FEV1, FEV1/FVC), 6MWD and reduce acute exacerbation, sputum volume and CAT score.