Venous thromboembolic events after cerebral vein thrombosis.

BACKGROUND AND PURPOSE After cerebral vein and dural sinus thrombosis (CVT), there is an increased risk of further venous thromboembolic events (VTEs). Time to a second cerebral or systemic venous thrombotic event and risk factors for recurrence have not been investigated in large prospective studies. METHODS We used the International Study on Cerebral Vein and Dural sinus Thrombosis, which included 624 patients with CVT followed up for a median of 13.9 months. Outcome measures included all symptomatic VTEs and CVT recurrence. Potential predictors of recurrence, including demographic characteristics, imaging features, thrombophilic abnormalities, other risk factors for CVT, and anticoagulation, were analyzed by Cox survival analysis. RESULTS Of the 624 included patients, 36 (5.8%) had at least 1 venous thromboembolic event. The rate of VTEs after the initial CVT was 4.1 per 100 person-years. Of all VTEs, 63.2% (n=24) occurred within the first year. Fourteen patients (2.2%) had an episode of recurrent CVT and the rate of recurrence was 1.5 per 100 person-years. Nine (64.3%) of these CVT recurrences occurred within the first year. Male gender (hazard ratios=2.6; 95% CI, 1.4 to 5.1; P=0.004) and polycythemia/thrombocythemia (hazard ratios=4.4; 95% CI, 1.6 to 12.7; P=0.005) were the only factors associated with a significant higher risk of VTEs in multivariate survival analysis. CONCLUSIONS The risk of recurrence of CVT is low but is moderate for other VTEs. Recurrence of venous thrombosis after CVT is more frequent among men and in patients with polycythemia/thrombocythemia.