Serum 25-hydroxyvitamin D, cardiovascular risk markers, and incident cardiovascular disease in a high risk community population.

BACKGROUND It is unclear whether vitamin D status is related to cardiovascular risk beyond that explained by conventional risk markers. We examined the relationship between serum 25-hydroxy (OH) vitamin D and incident cardiovascular disease (CVD; heart attack/stroke) after adjusting for individual- and community-level covariates from laboratory and administrative data. METHODS Patients receiving their first 25-OH vitamin D test in Calgary, Alberta from 2009-2013 without a past CVD diagnosis but an electrocardiogram and body mass index (BMI) +/- 3 months from testing were included. First results for lipid profile, fasting plasma glucose, and HbA1c measured +/- 3 months from testing were retrieved. Census dissemination area (CDA)-level indicators of socioeconomic status (SES) in 2011 as well as CVD diagnoses >3 months from testing between 2009 and 2016 were retrieved. Linear and Poisson regression were used to examine associations between 25-OH vitamin D quartile and covariates, and Cox proportional hazard models were used to examine associations with incident CVD before and after adjustment. RESULTS Among 72 348 patients, there were 1898 CVD events over a median of 6.0 years. Increasing quartile of 25-OH vitamin D was associated with improved lipid and glycemic profiles (p < 0.01), higher CDA-level SES indicators (p < 0.01), but importantly a lower risk of CVD (Q4 vs Q1: HR: 0.72, 95% CI: 0.63-0.81, p for trend < 0.01) after adjusting for age, sex and average daily hours of sunlight during month of testing. This was unaffected by adjustment for BMI, slightly attenuated by adjustment for SES but completely abolished by adjustment for laboratory-measured cardiovascular risk markers. CONCLUSIONS Vitamin D status likely offers no additional information on CVD risk over conventional laboratory-measured risk markers.