Rapid Uptake of New Oral Anticoagulants in AF Patients

August 22, 2014

BOSTON, MA — Physicians treating patients with atrial fibrillation (AF) have enthusiastically embraced the new oral anticoagulants, with more than 60% of all new prescriptions in June 2013 being filled for dabigatran (Pradaxa, Boehringer Ingelheim), rivaroxaban (Xarelto, Bayer Pharma/Janssen Pharmaceuticals), and apixaban (Eliquis, Bristol-Myers Squibb/Pfizer)[1].

The new drugs are considerably more expensive, too, with spending on novel oral anticoagulants accounting for 98% of all anticoagulant-related healthcare dollars, according to a new study. On average, patients paid $54 for warfarin in the first six months of their treatment, whereas dabigatran and rivaroxaban cost patients $205 and $221, respectively. For insurers, the cost of warfarin, dabigatran, and rivaroxaban in the first six months of treatment was $68, $852, and $865, respectively.

These numbers, according to lead researcher Dr Nihar Desai (Brigham and Women's Hospital, Boston, MA) and colleagues, "translate into billions of dollars at a national level."

In an editorial accompanying the study[2], Dr Joseph Alpert (University of Arizona College of Medicine, Tucson) said the oral anticoagulants have been a welcome addition for physicians who treat patients with AF, especially since there is no need for frequent monitoring of clotting, as with warfarin, and no need for dietary restrictions.

"However, as is often the case in clinical medicine, there is no perfect solution to any problem," he writes. The most important downside with these new drugs is the cost. Combined patient and insurer costs during the first six months of treatment is $900 higher with the new agents compared with warfarin.

"I always advise patients receiving a prescription for one of the novel oral anticoagulants to check with their insurance company before handing in the prescription to see what their copayment will be. The range that I have seen is from $30 per month to $140 per month," writes Alpert. "Often patients with very high copayment requirements choose to continue or initiate therapy with warfarin."

AF Landscape Changed in 2010

In the beginning, there was warfarin, but the AF landscape has been substantially altered in recent years. Dabigatran, a direct thrombin inhibitor, was approved for the prevention of stroke in October 2010. Rivaroxaban, a factor Xa inhibitor, was approved for the same indication in November 2011, and apixaban, also a factor Xa inhibitor, was approved in December 2012. Edoxaban (Lixiana, Daiichi Sankyo) and betrixaban (Portola Pharmaceuticals/Merck) are also in the pipeline and may one day join this changing field.

In the present analysis, which is published in the American Journal of Medicine, Desai and colleagues assessed nationwide medical and prescription claims data from patients covered by Aetna, a large US healthcare benefits company. They identified 6893 patients with nonvalvular AF newly started on an oral anticoagulant between October 2010 and June 2013. During this three-year period, there were 45 472 prescriptions filled for anticoagulants, including 58% for warfarin, 33% for dabigatran, 9.3% for rivaroxaban, and 0.1% for apixaban.

By October 2011, one year after the drug gained approval, patients were as likely to be prescribed dabigatran as they were warfarin, according to the analysis. Rivaroxaban use increased quickly, too, with more patients being treated with this drug than with warfarin and dabigatran by 2013. During the study period, apixaban was on the market for only six months, but there was still a modest increase in its use. By June 2013, 2% of prescriptions filled were for apixaban.

Peak dabigatran use occurred in October 2011, one year after approval and just before the introduction of rivaroxaban, and declined steadily since then. By June 2013, approximately 15% of patients were prescribed dabigatran compared with 44% at its peak. The researchers speculate the drop-off might be related to reports of an increased risk of MI and serious and fatal bleeding in dabigatran users, or it might be related to the twice-daily dosing of the anticoagulant.

The MI issue was even considered in a large Food and Drug Administration (FDA) review of dabigatran use in Medicare patients. The review has recently wrapped up, with the agency saying the drug posed no increased risk of MI when compared with warfarin.

In his editorial, Alpert points out there is no antidote to reverse the anticoagulant effect with these new drugs in the case of bleeding. For him, though, this is not a major concern, given the short half-lives of dabigatran, rivaroxaban, and apixaban. If the anticoagulants are discontinued, "normal anticoagulation returns in a relatively short time, particularly when compared with warfarin." He does urge caution by using lower doses of the new anticoagulants in elderly patients and those individuals also taking aspirin or clopidogrel.

Funding for the study was provided by an unrestricted grant from CVS Caremark to Brigham and Women's Hospital. Alpert is the editor in chief of the American Journal of Medicine and reports serving on the data safety and monitoring board for the ROCKET-AF and PIONEER studies, two trials involving rivaroxaban.

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