• venous thrombosis;
  • epidemiology;
  • interleukin 8;
  • inflammation;
  • risk factors

Summary. Elevated plasma levels of interleukin 8 (IL-8) were previously shown to be associated with recurrent venous thrombosis. To assess the risk of venous thrombosis, IL-8 plasma concentrations were measured in patients and control subjects of the Leiden Thrombophilia Study (LETS). This population based case–control study included 474 patients with a first deep-vein thrombosis and 474 age- and sex-matched controls. The risk of venous thrombosis for subjects with elevated IL-8 levels (above 90th percentile of controls) compared with subjects with IL-8 levels below the 90th percentile was increased 1·8-fold (95%CI 1·2–2·8). Adjusted for age and sex, the odds ratio was 1·9 (95%CI 1·3–2·8). IL-8 concentrations were weakly correlated with age, male sex, and concentrations of C-reactive protein, factor VIII coagulation activity and homocysteine, but adjustment for these factors did not substantially affect the association between IL-8 and venous thrombosis. Our results suggest that IL-8 is a risk factor for venous thrombosis.