Although warfarin is widely used to prevent strokes in patients with atrial fibrillation (AF), previous research has found the discontinuation rate to be high. In a study published online Aug. 6 in Circulation: Cardiovascular Quality and Outcomes, researchers found that a newer drug, dabigatran, resulted in better persistence rates in patients newly diagnosed with nonvalvular AF.

Warfarin (Coumadin, Bristol-Myers Squibb) therapy has demonstrated efficacy in reducing ischemic stroke risk in AF patients, but “largely because of the complex dosing regimen requiring frequent INR [International Normalized Ratio] monitoring, treatment with warfarin has been associated with both adherence and persistence issues,” the authors wrote.

Martin Zalesak, MD, PhD, of Trinity Partners, a consulting firm in Waltham, Mass. and his colleagues from Boehringer Ingelheim Pharmaceuticals and the Duke-NUS Graduate Medical School in Singapore, examined U.S. Department of Defense claims data to identiy patients taking warfarin or dabigatran (Pradaxa, Boehringer Ingelheim) between Oct. 2010 and June 2012. They included 5,145 patients who were newly diagnosed with nonvalvular AF and initiating either drug.

After six months of drug therapy, persistence rates were higher for dabigatran (72 percent) than for warfarin (53 percent). The rates were also higher after one year.

The authors linked certain factors to persistence for both drugs. Dabigatran persistence tended to increase with older age, higher stroke risk, lower risk of bleeding and more comorbidities. For warfarin, persistence was more likely with older patients, no history of intracerebral bleeding and residence in the Midwestern or Southern U.S. 

In addition to the improved persistence rates they found in their research, the authors noted dabigatran does not increase the risk of bleeding and does not require monitoring for INR.

Despite the advantages of dabigatran and the study findings, “[p]ersistence between these two therapies in the real world is not known,” they wrote.

Seven of the study authors are employed by Trinity Partners, a firm Boehringer Ingelheim hired as study collaborators. The study was funded by Boehringer Ingelheim.

For more on treatment options in AF, please read "Anticoagulants: The Brave New World."