Summary
Background
Some evidence suggests that an inadequate vitamin D level may increase the risk atherosclerotic cardiovascular disease. Whether low vitamin D has a role in venous thromboembolism (VTE), i.e., venous thrombosis and pulmonary embolism, is largely unexplored.
Objectives
We tested prospectively in the Atherosclerosis Risk in Communities (ARIC) cohort whether the serum concentration of 25-hydroxyvitamin D (25(OH)D) is inversely associated with VTE incidence and whether it partly explains the African American excess of VTE in ARIC.
Patients and Methods
We measured 25(OH)D using mass spectroscopy in stored samples of 12,752 ARIC study participants and followed them over a median of 19.7 years (1990-92 through 2011) for incidence of VTE (n = 537).
Results
The seasonally-adjusted 25(OH)D concentration was not associated with VTE incidence. In a model adjusted for age, race, sex, hormone replacement therapy, and body mass index, the hazard ratios of VTE across 25(OH)D quintiles 5 (high) to 1 (low) were: 1 (Ref.), 0.84 (0.65, 1.08), 0.88 (0.68, 1.13), 1.04 (0.78, 1.38), and 0.90 (0.64, 1.27). The lowest 25(OH)D quintile comprised 59% African Americans, whereas the highest quintile comprised 7% African Americans. Yet, lower 25(OH)D concentrations explained little of the 63% greater VTE risk of African Americans over whites in this cohort.
Conclusions
Low 25(OH)D was not a risk factor for VTE in this prospective study. Yet, the totality of literature (three studies) suggests that low 25(OH)D might modestly increase VTE risk in whites, but this needs further confirmation.