In contemporary patients with polycythemia vera, rates of thrombosis and risk factors delineate a new clinical epidemiology.

In multivariable analysis, previous arterial event (hazard ratio [HR], 1.7; 95% confidence interval [CI], 1.2 to 2.4) and hypertension (HR, 1.6; 95% CI, 1.2 to 2.2) were significantly associated with subsequent arterial events whereas previous venous event (HR, 2.6; 95% CI, 1.5 to 4.4) and age ≥65 years (HR, 1.7; 95% CI, 1.2 to 2.5) were significant predictors of future venous thrombosis.