Burkes RM, Ceppe AS, Doerschuk CM, et al. - Researchers investigated the links between baseline 25-hydroxy-vitamin D (25-OH-vitamin D) and cross-sectional and longitudinal lung function and COPD exacerbations, by using the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS). Stored samples from 1,609 SPIROMICS participants with COPD were analyzed for serum 25-OH-vitamin D level. 25-OH-vitamin D concentrations were modeled continuously and divided as deficient (< 20 ng/ml) vs not deficient (≥ 20 ng/ml). Findings revealed worse cross-sectional and longitudinal lung function as well as increased odds of prior COPD exacerbations in relation to vitamin D deficiency. The potential usefulness of 25-OH-vitamin D levels was indicated as a marker of adverse COPD-related results.