PB0929 - Comparison between full dose and reduced dose enoxaparin in the management of cancer-associated venous thromboembolism

Background: Treatment of cancer-associated venous thromboembolism (VTE) is challenging due to high rates of both recurrent thrombosis and major bleeding. Low molecular weight heparin remains the preferred anticoagulant in select patients. Trials evaluating dalteparin have reduced the dose after one month. The optimal enoxaparin dosing regimen for cancer-associated VTE remains uncertain.

Aims: To compare the efficacy and safety of full dose enoxaparin (1mg/kg twice daily or 1.5mg/kg daily) versus reduced dose enoxaparin (≤1mg/kg daily) in the management of cancer-associated VTE.

Methods: A single-centre, retrospective audit was performed on patients with active cancer and acute VTE between January 2014 and December 2018. All patients received full dose enoxaparin for at least the first 28 days. Following this, patients either remained on full dose enoxaparin or were changed to reduced dose enoxaparin, at their treating clinician’s discretion. The primary outcome was recurrent VTE at six months. All suspected recurrences were blindly adjudicated by two reviewers. Secondary outcomes were rates of ISTH-defined major bleeding and mortality. The study received institutional ethics committee approval.

Results: 257 patients (median age 64, 53% female) were identified with active cancer and acute VTE. 141 patients (55%) remained on full dose enoxaparin and 116 patients (45%) received reduced dose enoxaparin. Patient characteristics and outcomes are shown in Table 1 and Table 2. There was no difference in rates of recurrent VTE at six months between reduced dose enoxaparin and full dose enoxaparin (5.2% versus 5.7%, p=0.86). There was also no difference in major bleeding events (9.5% versus 7.1% p=0.49). Mortality was lower in patients who received reduced dose enoxaparin (16% versus 39%, p< 0.01). 97% of deaths were due to cancer, with no deaths attributable to VTE or bleeding.

Conclusion(s): The efficacy of reduced dose enoxaparin appears comparable to full dose enoxaparin in the management of cancer-associated VTE, though without less major bleeding.