Abstract 3611: Cardiovascular risk factors and venous thromboembolism: A meta-analysis

Background: The concept that venous thromboembolism (VTE) and atherosclerosis are two distinct entities has recently been challenged. Patients with spontaneous VTE had more asymptomatic carotid atherosclerotic lesions and a higher incidence of cardiovascular disease than patients with VTE secondary to known risk factors and controls. However, no clear relationship between cardiovascular risk factors and VTE has ever been determined. We performed a meta-analysis to assess the potential association between well known cardiovascular risk factors and VTE. Methods: Medline and EMBASE databases were searched to identify studies that evaluated the prevalence of major cardiovascular risk factors in VTE patients and in controls. The studies were selected using a priori defined criteria and each study was reviewed by two authors who abstracted data on study characteristics, study quality and outcomes. Odds Ratio (OR) or weighted mean differences and 95% confidence intervals (CI) were calculated and pooled using a random-effects model. Statistical heterogeneity was evaluated using the I 2 statistic. Results: Twenty-one case-control and cohort studies with a total of 63.552 patients met the inclusion criteria. Compared to controls, the risk of VTE was 2.33 for obesity (95% CI 1.68 –3.24), 1.51 for hypertension (1.23–1.85), 1.42 for diabetes (1.12–1.77), 1.18 for smoking (0.95–1.46), and 1.16 for hypercholesterolemia (0.67–2.02). Weighted mean HDL cholesterol levels were significantly lower in VTE patients compared to controls, whereas no difference was observed in total cholesterol and LDL cholesterol levels. Significant heterogeneity among studies was detected in all subgroups, except for diabetes. Higher quality studies were more homogeneous and, except for hypertension, the significant associations remained unchanged. Discussion: Common cardiovascular risk factors are associated with an increased risk of VTE. This association between VTE and atherothrombosis has obvious clinical implications with respect to screening, risk factor modification and future therapy. Future prospective studies could investigate underlying mechanisms of this two-way relation.