Epidemiology of venous thromboembolism in 9489 patients with malignant glioma.

The authors sought to define the incidence of symptomatic venous thromboembolism (VTE) in patients harboring malignant gliomas. The authors conducted a retrospective analysis of data obtained in all cases of malignant glioma diagnosed in California during a 6-year period; the occurrence of a VTE was identified using linked hospital discharge data. The Cox proportional hazard model was used to analyze the association of specific risk factors with the development of a VTE or death within 2 years of the cancer diagnosis. Among 9489 cases, the 2-year cumulative incidence of VTE was 7.5% (715 cases), with a rate of 16.1 events per 100 person-years during the first 6 months. Three hundred ninety-one (55%) of these 715 cases were diagnosed within 61 days of major neurosurgery. Risk factors for VTE included older age (hazard ratio [HR] 2.6, confidence interval [CI] 2.0-3.4 for age range 65-74 years compared with < or = 45 years), glioblastoma multiforme histology (HR 1.7, CI 1.4-2.1), three or more chronic comorbidities (HR 3.5, CI 2.8-4.3 [compared with no comorbidity]), and neurosurgery within 61 days (HR 1.7, CI 1.3-2.3). Patients in whom a VTE was present were at higher risk of dying within 2 years (HR 1.3, CI 1.2-1.4). In a nested case-control analysis of all VTE cases, there was no association between insertion of a vena cava filter and the risk of a recurrent VTE. In patients harboring a glioma there was a very high incidence of symptomatic VTEs, particularly within 2 months of neurosurgery. The development of a VTE was associated with a 30% increase in the risk of death within 2 years. Further studies are needed to determine if risk stratification and the use of medical prophylaxis after neurosurgery improves outcomes.