#111 A pill for the second clot I do not want
CLINICAL QUESTION
Are novel anti-coagulants as effective as warfarin in treating acute venous thromboembolism (VTE)?
BOTTOM LINE
Studies show novel anti-coagulants are non-inferior to warfarin in the treatment of VTE and generally have less major bleeding. Regulatory approval, patient values, and drug costs should help in deciding which therapy to use.
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EVIDENCE
Five large, industry-funded, non-inferiority randomized clinical trials compared available novel oral anticoagulants to warfarin. Patients’ mean age 55-58 years, ~60% men, ~20% with previous VTE, significant renal impairment excluded.
- Rivaroxaban: 15mg bid x three weeks, then 20mg qd for three, six, or 12 months for 3,449 deep vein thrombosis (DVT)1 and 4,832 pulmonary embolism (PE)2 patients had:
- Similar rates of: recurrent VTE (2-3%), major or clinically significant bleeding (8-11%), and death (2-3%).
- Dabigatran: 150mg bid for six months in 5,107 DVT or PE patients3,4 had:
- Similar rates of recurrent VTE: ~2-2.5%.
- Statistically significantly less major or clinically relevant bleeding: 5.3% vs. 8.5%, Number Needed to Treat (NNT) 32.
- More acute coronary syndromes (9 vs. 5) but statistics not reported.
- Apixaban: 10mg bid x seven days, then 5mg bid x six months in 5,395 DVT or PE patients5 had:
- Similar rates of recurrent VTE or VTE-related death: 2.2% vs. 2.6%.
- Statistically significantly less major or clinically significant bleeding: 4.3% vs. 9.7%, NNT 19.
- Non-inferiority margins set higher than clinically important differences:
- Rivaroxaban considered non-inferior to warfarin if had ≤twice the number of recurrent VTEs. Dabigatran margins set higher, apixaban lower.
- Warfarin time in therapeutic range ~60%, lower earlier in studies.1-5
- Compared to placebo, extending novel oral anticoagulant therapy decreases VTE recurrence which is partially offset by increased bleeding.1,6,7
- Extending treatment with aspirin also decreases VTE recurrence.8
- LMWH is recommended for treating VTEs in cancer patients.9
- Only rivaroxaban is currently approved in Canada for VTE treatment.10
- Drug costs, six months (Alberta): rivaroxaban ~$625, warfarin ~$40.11
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