Associations between vitamin D and cardiovascular outcomes; Tehran Lipid and Glucose Study.

Background: Vitamin D status seems to have an association with cardiometabolic risk factors and its deficiency may negatively affect the cardiovascular outcomes. The aim of this study was to determine the possible association between vitamin D status and cardiovascular outcomes.

Method: We performed a nested case control study within the Tehran Lipid and Glucose Study (TLGS), which followed a representative sample of Tehranian adults. A total of 251 matched pairs, aged>30 years, were selected. Cases were TLGS individuals that were free of cardiovascular disease (CVD) at the beginning of study and developed CVD during assessments of 5.7 year follow up. Each case was matched by age, sex and the month of entry to study with a randomly selected control (risk-set sampling). Prespecified cut points were used to characterize varying degrees of 25-OH D deficiency (<10, between 10 and 14.9, and ≥ 15 ng/ml). Conditional logistic regression was used to investigate the association between 25-OH-D concentration and the incident cardiovascular outcomes.

Results: The mean age of participants was 56.84 ± 11.17 years and 244 (48.6%) were women. The median (IQ: 25-75) of serum 25-OH-D was 14.1 ng/ml (9.6-29 ng/ml) and 306 (61%) of participants had serum 25-OH-D<15 g/ml. Median serum 25-OH-D was lower in cases (12.5 vs. 18.1, P<0.001). After adjustment for potential confounders, the odds ratio of serum 25-OH-D<10 ng/ml for having CVD outcomes was 2.90 compared with 25-OH-D ≥ 15 (95% confidence interval (CI): 1.67-5.12, P<0.001).

Conclusion: Our results indicate that serum 25-OH-D concentration has an independent association with cardiovascular outcomes in adult Tehranians.