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New Anti-Clotting Drug Bests Warfarin, Study Says


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New Anti-Clotting Drug Bests Warfarin, Study Says

Our Review Summary

There’s a great discussion to be had about the best ways to reduce stroke risk and the pharmaceutical approaches on the horizon, but this story takes too much on faith from a press release and a researcher getting paid by the pharmaceutical company marketing the drug in question.


Why This Matters

Patients with atrial fibrillation have a recognized higher likelihood of having a stroke than those without the heart rhythm abnormality.  In order to reduce the risk of stroke, two drugs have been traditionally employed; aspirin and warfarin.  Although warfarin has been shown to be better at reducing the risk of stroke than aspirin, it has a much higher bleeding complication rate.  And, warfarin therapy must be routinely monitored with blood tests and the dose adjustments made to maintain an adequate level of anticoagulation.  Aspirin is used when the patient’s risk of bleeding is larger than their risk of stroke.  Newer drugs, without the need for constant titration, that work as well as well controlled warfarin therapy and without as high a risk of bleeding have recently become available.  Apixaban is the pharmaceutical industry’s latest attempt to replace warfarin for this indication.

While perhaps easier to use, the newer agents come at a financial and potentially a clinical cost.  These newer drugs cost up to $300 per month and are more expensive than the combined cost of warfarin and routine blood testing.  An earlier version of a warfarin replacement looked good in early trials and was approved by the FDA only to be withdrawn because of liver toxicity with long term treatment. The New Drug Application for apixaban has been delayed twice by the Food and Drug Administration.


Does the story adequately discuss the costs of the intervention?

Not Satisfactory

There is no mention of costs in this story, even though apixaban has been found to be quite costly. A study in Nature Cardiology, for example, found that apixaban cost $3,545 per patient compared to $1,805 for patients treated with aspirin.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The story does quantify the benefits, albeit only in relative terms. The story says, “Apixaban showed a 21 percent relative reduction in the incidence of strokes or systemic embolisms (clots) when compared to warfarin, a 31 percent relative reduction in major bleeding and an 11 percent relative reduction in overall mortality, the researchers found.” We would have liked to have seen these comparisons in absolute terms. When you read in the story, for example, that 18,000 patients were studied, you might assume that a huge number of them died, meaning that 11% percent difference represents hundreds of people. In reality, the differences were quite small.  For example, the 21% relative reduction in stroke or embolism is an absolute difference of 1.27% with apixaban as compared to 1.6% with warfarin. The 31% relative risk reduction in major bleeding is an absolute difference of 2.13% with apixaban and 3.09% with warfarin.  This is a great example of why absolute numbers are so important in this type of story.

Does the story adequately explain/quantify the harms of the intervention?

Not Satisfactory

The story does not mention any potential harms from long term or short term use of apixaban.

Does the story seem to grasp the quality of the evidence?

Not Satisfactory

The story really explains very little about the study design. In many ways, the study does seem very impressive. As the study abstract explains, “ARISTOTLE was a double-blind, randomised trial that enrolled 18 201 patients with atrial fibrillation in 39 countries. Patients were randomly assigned apixaban 5 mg twice daily (n=9120) or warfarin (target international normalised ratio 2·0—3·0; n=9081). The primary endpoint was stroke or systemic embolism.” Some details from the study would have been important for people to understand the importance of the results, and, at the same time, some discussion of the limitations of the study would have provided important context.

Does the story commit disease-mongering?


There was no disease mongering in the story. It simply provides a short explanation of the disorder, saying, “Atrial fibrillation affects more than 2.6 million people in the United States. In people with atrial fibrillation, disorganized electrical activity causes ineffective contraction of the upper chambers of the heart. This increases the risk for blood clots that can cause stroke.”

Does the story use independent sources and identify conflicts of interest?

Not Satisfactory

There were no independent sources in the story, as the story itself says at the bottom: “SOURCES: Jack Ansell, M.D., chairman, department of medicine, Lenox Hill Hospital, New York City; Duke Medicine, news release, Oct. 1, 2012” The story does point out that Ansell is “a consultant to Bristol-Myers Squibb and Pfizer, the companies that are marketing the drug as Eliquis.” But it does not point out the more important fact that those companies funded the study.

The article was accompanied by an editorial that provided both context and balance.  Regrettably, the story did not provide either.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

There are other existing drugs (Xarelto and Pradaxa) used as warfarin replacements that were not mentioned.  The absence of this information makes it appear that apixaban is the only game in town and it is clearly not.

Does the story establish the availability of the treatment/test/product/procedure?


The story explains that the drug has not yet been approved by the FDA.

Does the story establish the true novelty of the approach?

Not Satisfactory

The story makes a very bold claim by quoting the press release about the study. It says, “With new oral anticoagulants, such as apixaban, we might not need risk scores to guide treatment decisions for stroke prevention in patients with atrial fibrillation. This may simplify how physicians make decisions and also improve patient care.” The implication is clear: Throw away risk scores because apixaban is just that safe. The story does not provide enough evidence to let that claim go unchallenged.

Does the story appear to rely solely or largely on a news release?

Not Satisfactory

The first quote in the story comes from the press release. Normally, this wouldn’t disqualify a story in this category, but the story did not provide any outside perspective to counter the overall feel of the piece, which comes across like a press release or advertisement.

Total Score: 2 of 10 Satisfactory


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