#73 Novel Oral Anti-coagulants (NOACs): is newer better?
CLINICAL QUESTION
For patients with non-valvular atrial fibrillation (AF), do the NOACs (dabigatran, rivaroxaban, apixaban) have advantages over warfarin?
BOTTOM LINE
Compared to warfarin, NOACs offer some benefits for patients with non-valvular atrial fibrillation. The decision to use a NOAC or warfarin should be made after reviewing the patient’s previous INR stability, kidney function and discussing the potential benefits and risks, direct and indirect costs with the patient.
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EVIDENCE
All randomized controlled trials compared NOACs to warfarin: patients mean age 70-73 years, 35-40% female, 1.8-2 years follow-up. All outcomes versus warfarin:
- Dabigatran: 150mg BID or 110mg BID,1,2 18, 113 patients, mean CHADS2=2.1.
- Stroke & systemic embolism:
- 150mg: 0.60% less/year, Number Needed to Treat (NNT)=167.
- 110 mg: No statistical difference.
- Major Bleed:
- 150mg: No statistical difference.
- 110mg: 0.70% less/year, NNT=143.
- o Mortality:
- 150mg: Borderline significance [p=0.051, absolute difference would be 0.49% less/year, NNT=205].
- 110mg: No statistical difference.
- Stroke & systemic embolism:
- • Rivaroxaban: 20mg QD,3 14,264 patients, mean CHADS2=3.5.
- Stroke & systemic embolism, major bleed, or mortality: No statistical difference.
- • Apixaban: 5mg BID,4 18,201 patients, mean CHADS2=2.1
- Stroke & systemic embolism: 0.33% less/year, NNT=303.
- Major Bleed: 0.96% less/year, NNT=104.
- Mortality: 0.42% less/year, NNT=238.
- While statistical significance was achieved in some endpoints, whether clinically meaningful differences exist between the agents is unknown.
- In Canada, only dabigatran and rivaroxaban are currently approved for AF stroke prevention.
- Appropriate patient selection important:
- Use CHADS2, time in therapeutic INR range, and tools http://www.vhpharmsci.com/sparc/ to aid discussion.
- NOACs contra-indicated in patients with significant renal impairment (CrCl < 30 mL/min), use lower doses if moderate renal impairment (CrCl 30-50 mL/min).5
- Major bleeding occurs with all anticoagulants:
- NOACs: no established reversal strategy.
- Bleeding risk factors: (primarily from dabigatran experience): age > 80 years, impaired6 or deteriorating renal function5, < 60 kg6, and starting before INR < 2.0.6
- Potential risk of myocardial infarction (dabigatran): Number Needed to Harm (NNH)=250-500.1,2,7
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This needs to be updated since apixaban is approved in Canada and reversal agents do exist for NOACS
Interesting.