Increased risk of CVD after VT is determined by common etiologic factors

Patients with venous thrombosis (VT) have an increased risk of subsequent CVD (CVD), but the underlying pathophysiology is unclear. Using data from the Multiple Environmental and Genetic Assessment of risk factors for venous thrombosis follow-up study, 4480 patients with VT, 2926 partner control participants, and 2638 random digit dialing (RDD) control participants were followed-up between 1999 and 2008. Incidence rates and hazard ratios with 95% confidence intervals (95% CIs) of CVD (defined as myocardial infarction or ischemic stroke) were calculated for patients vs controls. Measurable confounders (age, sex, body mass index, smoking, chronic disease, malignancy, genetic thrombophilia, and procoagulant markers) were adjusted for when comparing patients with RDD controls. Unmeasured lifestyle-related factors were also considered by comparing patients with their partners. During a median follow-up time of 5 years, 124 CVD events occurred. Incidence of CVD per 1000 person-years was 3.2 (95% CI, 2.5-4.0) in patients, 2.2 (95% CI, 1.5-3.0) in partners, and 1.6 (95% CI, 0.9-2.6) in RDD controls. Crude hazard ratio was 2.2 (95% CI, 1.2-3.8) in patients compared with RDD controls and 1.5 (95% CI, 1.0-2.3) in patients compared with partners. After adjustment for all confounders, these risks attenuated to 1.8 (95% CI, 0.8-4.2) and 1.3 (95% CI, 0.7-2.5) for patients compared with RDD control participants and partners, respectively. In conclusion, individuals with VT had an increased risk of CVD. This could be explained by common etiologic factors.