Novel oral anticoagulants work as well as warfarin


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Clinical trials have shown that novel oral anticoagulants (NOACs) are as efficacious as warfarin in reducing the risk of stroke in patients with atrial fibrillation, reports the MJA.

Notwithstanding, the reaserchers say that concerns remain regarding the efficacy of NOACs in real life situations, given the study looked at patients older than 75 with other health conditions.

Three NOACs — dabigatran, rivaroxaban and apixaban — were listed by the PBS  in 2013, but there is little information about their uptake in clinical practice in Australia, say researchers.

“We conducted a retrospective observational study to examine overall use and initiation of oral anticoagulants, and the characteristics of patients for whom they are prescribed. We used administrative claims data from the Veterans’ Affairs for patients who were full entitlement holders. Researchers say that Monthly rates of NOAC and warfarin use were calculated from 1 January 2012 – 31 August 2014, and numbers of veterans initiated each month on low-dose and high-dose NOACs were calculated for the period 1 September 2013 – 31 August 2014. Clinical characteristics of new users of NOACs or warfarin (patients who hadn’t used warfarin in the previous 12 months) were compared,” say researchers.

In the year after NOACs were listed on the PBS, the overall rate of anticoagulation therapy increased, while the rate of warfarin use actually decreased There were 3936 and 1506 new users of NOACs and warfarin, respectively. The median age of patients in the cohort was 86 years. And the use of low-dose formulations of NOACs was most common, potentially reflecting impaired renal function in this older population, the MJA reports

Those on NOACs were younger, more likely to be men, had fewer comorbidities, and were less likely to be in aged care facilities. Also, use of DAAS was similar for NOAC and warfarin users (10.6% [416/3936] and 10.7% [161/1506] respectively). But those initiated on NOACs had fewer hospitalisations recorded in the previous 12 months for gastrointestinal bleed, stroke and myocardial infarct compared with those initiated on warfarin. Also, the concomitant use of antithrombotic medicines was significantly lower in those initiated on NOACs compared with those initiated on warfarin (21.0% [803/3819] v 35.1% [491/1397], P < 0.0001). Non-steroidal anti-inflammatory drug use was greater in those patients started on NOACs (Together with the lack of reversibility of the anticoagulation effect of NOACs, these results are of concern and suggest that prescribers should consider the potential risk of bleeds when NOACs are co-administered with medicines such as non-steroidal anti-inflammatory drugs. This analysis was performed in an older veteran population and may not be relevant to the wider Australian population.

The researchers say that the overall increased use of oral anticoagulants since the introduction of NOACs may reflect use in patients who were previously considered unsuitable for warfarin. They say that it appears that pre-existing risk factors are being considered by prescribers when making the choice between NOACs and warfarin. However, they stress that prescribers need to remain vigilant to the risk of bleeding with NOACs, particularly in patients who are taking other medicines that might increase bleeding risk.

 

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