Increased risk of arterial thromboembolism after a prior episode of venous thromboembolism: results from the Prevention of REnal and Vascular ENd stage Disease (PREVEND) Study

Large population-based studies are needed to establish the magnitude and duration of the recently suggested association between arterial and venous thromboembolism. In 1997-98, all inhabitants of Groningen, the Netherlands, aged 28-75 years (n = 85 421), were invited to participate in a study that followed and monitored responding subjects (n = 40 856) for venous and arterial thromboembolism until 2009. Thromboembolism was verified with national registries of hospital discharge diagnoses and death certificates, anticoagulation clinic and medical records. During a median follow-up of 10·7 years, 549 participants developed venous thromboembolism and 3283 developed arterial thromboembolism. Annual incidence of arterial thromboembolism after venous thromboembolism was 2·03% [95% confidence interval (CI), 1·48-2·71], compared to 0·87% (95% CI, 0·84-0·90) in subjects without venous thromboembolism. The hazard ratio (HR) of arterial thromboembolism after venous thromboembolism was 1·40 (95% CI, 1·04-1·88) after adjustment for age, sex and cardiovascular risk factors. This risk was highest during the first year after venous thromboembolism [annual incidence, 3·00% (95% CI, 1·64-5·04); adjusted HR, 2·01 (95% CI, 1·19-3·40)] and after an unprovoked event [annual incidence, 2·53% (95% CI, 1·68-3·66); adjusted HR, 1·62 (95% CI, 1·11-2·34)]. This study showed that subjects with venous thromboembolism are at increased risk for arterial thromboembolism, particularly in the first year after venous thromboembolism and after an unprovoked event.