Epidemiology of venous thromboembolism in 9489 patients with malignant glioma

Object. The authors sought to define the incidence of symptomatic venous thromboembolism (VTE) in patients harboring malignant gliomas. Methods. 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 <= 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. Conclusions. 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.