Though anticoagulants are common frontline treatment for patients with venous thromboembolism (VTE), patients with cancer who develop VTE may be at an increased risk for bleeding – complicating treatment decisions about VTE prophylaxis. At the 22nd Congress of the European Hematology Association, Alejandro Lazo-Langner, MD, from Western University in London, Ontario, and colleagues presented results from a retrospective, population-based cohort study designed to determine the risk-benefit profile of anticoagulant therapy in patients with cancer and VTE.
The authors determined that "the seven-day mortality after a major bleeding event is at least nine times higher than after a VTE recurrence, although the estimate is imprecise," questioning whether anticoagulation therapy is worth the risk in certain patients with cancer and VTE.
The researchers analyzed de-identified information from administrative databases housed at the Institute for Clinical Evaluative Sciences (a non-profit health services research institute in Toronto, Canada). They included patients >65 years old with cancer who developed a VTE event within six months of the initial cancer diagnosis (mean age = 75 years; range not provided). Recurrent VTE and major bleeding events (including upper and lower gastrointestinal and intracranial bleeding events) were assessed within 180 days of the index date. Next, they estimated mortality within seven days of the VTE recurrence or major bleeding event and analyzed ratios of bleeding-related mortality, compared with VTE recurrence-related mortality.
Treatment (the first available prescription for an anticoagulant within 7 days of the index VTE event) included:
- low-molecular-weight heparin (LMWH) alone: 59.9%
- warfarin alone: 22.1%
- LMWH followed by warfarin: 15.3%
- rivaroxaban: 2.7%
Between 2004 and 2014, 6,967 VTE events were recorded.
At 180 days after the index VTE event, the authors identified 235 major bleeding events (3%) and 1,184 VTE recurrences (17%). Within seven days of the outcome event, there were 26 deaths after major bleeding (11%) and six deaths after VTE (0.5%). The mortality ratio for major bleeding versus VTE was 21.8 (95% CI 9-53).
The researchers did not find differences based on anticoagulant prescription. "[These] data should be taken into consideration when designing studies and interventions involving anticoagulant therapy in this population," they concluded.
The study is limited by its retrospective design.
The study authors report no relevant conflicts of interest.
Lazo-Langner A, Louzada M, Garg A, et al. Assessing the risk-benefit of anticoagulants in elderly patients with cancer-associated venous thromboembolism: a population based study. Abstract #S441. Presented at the 22nd Congress of the European Hematology Association, June 24, 2017; Madrid, Spain.