ABO blood group is a potent risk factor for venous thromboembolism in patients with malignant gliomas

BACKGROUND: Venous thromboembolism (VTE) is a common cause of morbidity and mortality among patients with malignant gliomas. To investigate the pathogenesis of VTE and facilitate targeted prophylaxis strategies, the authors aimed to characterize VTE risk factors in these patients. METHODS: The authors conducted a retrospective chart review of 130 adult patients with glioma who received their primary therapy at the Johns Hopkins Hospital (Baltimore, MD) between 1991 and 2001. Symptomatic VTE was confirmed by objective radiologic testing. The association between clinical and laboratory characteristics and VTE was assessed using parametric and nonparametric statistical tests and survival analysis. RESULTS: VTE developed in 28 patients (21.5%) at a median of 4.8 months after diagnosis (interquartile range, 2.1-13.2). Patients with tumors > 5 cm were more likely to develop VTE than patients with smaller tumors (hazard ratio = 2.2; P = 0.04). For every year increase in age, the hazard ratios for thrombosis increased by 3% (P = 0.011). When stratified by ABO blood group, the hazard ratios for thrombosis were 2.7 and 9.4 for patients with blood groups A (P = 0.045) and AB (P < 0.0001), respectively, compared with patients with blood group O. No association was observed between VTE and the other patient characteristics analyzed. CONCLUSIONS: Patient age, tumor size, and particularly ABO blood group are risk factors for VTE among patients with malignant gliomas. These findings may facilitate the development of a thrombosis risk score that will allow physicians to individualize VTE prophylaxis regimens.