Vitamin D status in COPD patients at Chris Hani Baragwanath Hospital

Abstract

Background: There has been a growing interest in nutritional/ lifestyle factors, including vitamin D, that may impact Chronic Obstructive Pulmonary Disease (COPD). Most data are in Caucasian populations and temperate climates with minimal African (ethnicity and geographical) data. Objectives: The primary objective was to determine amongst COPD patients the prevalence of vitamin D deficiency (25 [OH]D ≤ 20 ng/ml) and insufficiency (25[OH]D - 21-29 ng/ml). Secondary objectives were to investigate the association between vitamin D and demographic/lifestyle factors; lung function parameters; markers of COPD severity and corticosteroid usage. Methods: A prospective, cross-sectional study of 76 COPD patients was conducted at a tertiary Johannesburg hospital. Patients were interviewed regarding demographic/lifestyle factors, COPD severity markers and corticosteroid therapy. The most recent spirometry was recorded. Blood samples were taken for calcium, alkaline phosphatase and vitamin D. Patients were stratified according to vitamin D status (deficiency and non-deficiency) and statistical analysis was performed to assess for associations. Results: The sample included 72% males and 63% black/ African patients. The prevalence of vitamin D deficiency and insufficiency were 48% (95% confidence interval [CI] 42 -54) and 35% (CI 30-41), respectively. The Modified Medical Research Council (MMRC) dyspnoea scale of ≥2 was associated with a relative risk of 1.34 (CI 1.05-1.7) for vitamin D deficiency in univariate analysis. In multivariate regression only sunlight exposure (<1 hour/day) was an independent predictor of vitamin D deficiency (Odds ratio 2.4, CI 1.3 -4.5) Conclusion: A high prevalence of suboptimal vitamin D levels exists within this sample COPD population. A higher MMRC score was associated with an increased risk of vitamin D deficiency while low sunlight exposure was the only independent predictor of vitamin D deficiency.