Bleeding or clotting in elderly patients with cancer-associated venous thromboembolism: which is worse?

The risk of venous thrombosis (VTE) is higher in cancer patients, and so is the risk of bleeding. Whereas anticoagulant therapy lowers the risk of thrombosis recurrence, it further increases the risk of bleeding. Previous studies suggested that the risks of dying from a thrombosis recurrence or bleeding are similar, but such findings may not apply to cancer patients. Therefore, Lazo-Langner and colleagues sought to estimate the risk and benefit of anticoagulant therapy in cancer patients developing a VTE using data from administrative databases.

This population-based retrospective cohort study conducted in Ontario, Canada, included patients who were ≥ 65 years with cancer and a VTE diagnosed within 6 months of the initial cancer diagnosis. VTE was identified through a previously validated algorithm using a combination of diagnostic codes for deep vein thrombosis (DVT) and pulmonary embolism (PE) and codes identifying diagnostic procedures for VTE (i.e. ultrasound, CT pulmonary angiography, lung scintigraphy) within 7 days of each other. Recurrent VTE and major bleeding (MB) events were assessed within 6 months of the initial VTE. MB was identified using a previously validated algorithm and included upper and lower gastrointestinal and intracranial bleeding events. The VTE recurrence, MB and the 7-day mortality after VTE recurrence or MB events, as well as the ratio of the mortality for MB compared to VTE recurrence were estimated.

Between 2004 and 2014 there were 6.967 VTE events identified in cancer patients over 65 years of age and treated with an anticoagulant. Mean age was 75 years, and 47.6% patients were women. Of all patients, 59.9% received prescriptions for LMWH alone, 15.3% for LMWH followed by warfarin, 22.1% for warfarin and 2.7% for rivaroxaban. At 6 months of the initial VTE, there were 235 (3%) MB events and 1.184 (17%) VTE recurrences. The 7-day mortality rate was 0.5% for VTE and 11% for MB with a ratio of 21.8 (95% CI 9-53). There were no differences between anticoagulants.

In conclusion, this study suggests that the use of anticoagulants in patients 65 years or older with cancer-related thrombosis results in an at least 9 times higher mortality if they develop a major bleeding event, compared to a VTE recurrence. This information should be confirmed in further studies and taken into account when designing studies and interventions in this population.

Reference

Lazo-Langner A, Louzada M, Garg A. Assessing the risk-benefit of anticoagulants in elderly patients with cancer-associated venous thromboembolism: a population based study. EHA 2017, oral presentation, abstract S441.