Abstract

Introduction: In cross-sectional studies, low serum levels of 25-hydroxyvitamin D are associated with a higher prevalence of cardiovascular risk factors. This study aimed to determine whether vitamin D deficiency is related to cardiovascular disease. Material and Methods: This nested case-control study was performed within the framework of a population-based Cohort study (Tehran Lipid and Glucose Study, TLGS) among male and female participants, aged 30 years or older (mean [SD] age, 56.7 [10.6] years), free of diagnosed cardiovascular disease at initial blood collection. Using risk set sampling, controls (n=251) were selected in a 1:1 ratio and matched for age, sex and date of blood collection. We measured serum 25-hydroxyvitamin D levels in serum specimens,  kept at -80°C until assay. Results: Median serum 25(OH)D was significantly lower in the CVD group than in controls (p<0.001). For 25(OH)D values of less than 10 ng/ml, compared with values more than 20 ng/ml (reference), the multivariable-adjusted OR (with 95% confidence intervals) for incident cardiovascular events was 3.21 (1.75-5.88). Conclusion: Low levels of 25(OH)D are independently associated with higher risk of cardiovascular events in a graded manner, even after adjustment for factors known to be associated with coronary artery disease.