Cardiovascular, bleeding, and mortality risks in elderly medicare patients treated with dabigatran or warfarin for nonvalvular atrial fibrillation.

We have entered a new era with novel oral anticoagulants specifically targeted at thrombin (e.g. dabigatran) or factor Xa (e.g. rivaroxaban, apixaban, or edoxaban). In a myriad of clinical trials, these agents have been shown to be as good as or better than conventional oral anticoagulants, i.e. vitamin K antagonists, in patients with atrial fibrillation and venous thromboembolism. However, it is well known that real-life clinical practice outcomes may differ from results in clinical trials. Hence, it is very useful to record safety information on patients in regular clinical settings.

In this study, the authors collected information on 134,414 mostly elderly patients (37,587 person-years follow up) from a Medicare database who initiated dabigatran or the vitamin K antagonist warfarin for prevention of thromboembolic complications in atrial fibrillation. Patients were compared after correction for propensity matched risk factors. Hazard ratios for ischaemic stroke, acute myocardial infarction and death were reduced by about 10% with dabigatran (150 mg twice daily) compared to vitamin K antagonists. The risk of intracranial haemorrhage was markedly lower in the dabigatran group (HR 0.34, 95% confidence interval 0.26-0.46). In contrast, the risk of gastrointestinal bleeding was higher in dabigatran-treated patients (HR 1.24, 95% confidence interval 1.14-1.44). The group of patients treated with a 50% lower dose of dabigatran (75 mg twice daily) intended for patients with renal impairment but applied in this study for many other patient groups) had similar outcomes compared to warfarin except for a lower dabigatran-associated risk for intracranial haemorrhage.

This is a very useful study demonstrating that in real-life use in elderly patients (who were underrepresented in clinical studies so far) novel oral anticoagulants confer a benefit over conventional anticoagulation with vitamin K antagonists. This information supports the introduction of this new class of agents in clinical practice.

– Marcel Levi

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