Associations between 25-hydroxy-vitamin D levels, lung function, and exacerbation outcomes in COPD: An analysis of the SPIROMICS cohort

Abstract Introduction The relationship between 25-hydroxy-vitamin D (25-OH-vitamin D) and COPD outcomes remains unclear. Using the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS), we determined associations between baseline 25-OH-vitamin D and cross-sectional and longitudinal lung function and COPD exacerbations. Methods Serum 25-OH-vitamin D level was measured in stored samples from 1609 SPIROMICS participants with COPD. 25-OH-vitamin D levels were modeled continuously and dichotomized as deficient ( Results Vitamin D deficiency was present in 21% of the cohort and was more prevalent in the younger-aged, active smokers, and African-Americans. Vitamin D deficiency was independently associated with 4.11 lower FEV1 %-predicted at enrollment (95% CI -6.90 to -1.34 %-predicted, P=0.004), 1.27 %-predicted greater rate-of-FEV1-decline after one year (95% CI -2.32 to -0.22 %-predicted/yr; P=0.02), and higher odds of any COPD exacerbation in the prior year (OR 1.32; 95% CI 1.00-1.74; P=0.049). Each 10 ng/ml decrease in 25-OH-vitamin D was associated with lower baseline lung function [-1.27 %-predicted (95% CI -2.32 to -0.22 %-predicted); P=0.02] and increased odds of any exacerbation in the year prior to enrollment [OR 1.11 (95% CI 1.01-1.22); P=0.04]. Interpretation Vitamin D deficiency is associated with worse cross-sectional and longitudinal lung function and increased odds of prior COPD exacerbations. These findings identify 25-OH-vitamin D levels as a potentially useful marker of adverse COPD-related outcomes.