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New Findings Support Safety and Efficacy of Dabigatran (Pradaxa) for Atrial Fibrillation

Largest observational study of newer oral anticoagulant

An FDA-sponsored study of more than 134,000 Medicare patients found that dabigatran etexilate mesylate (Pradaxa) was associated with significantly reduced risks of ischemic stroke, intracranial hemorrhage, and death, but significantly increased the risk of major gastrointestinal (GI) hemorrhage, compared with warfarin in patients with non-valvular atrial fibrillation (NVAF).

The study found no difference in major bleeds or in myocardial infarction with dabigatran compared with warfarin. According to the drug’s developer (Boehringer Ingelheim), the study, which was published online October 30 in Circulation, reinforces the favorable benefit–risk profile of dabigatran, as shown in the pivotal RE-LY trial for stroke risk reduction in patients with NVAF.

The FDA study was based on data from patients older than 65 years enrolled in Medicare who started therapy with dabigatran or warfarin between October 2010 and December 2012. Each group comprised 67,207 patients. The analysis showed that dabigatran was generally associated with better patient outcomes compared with warfarin. The primary outcomes included the following:

  • 20 percent reduced risk of ischemic stroke (hazard ratio [HR]: 0.80; 205 vs. 270 events)
  • No difference in major hemorrhage (HR: 0.97; 777 vs. 851 events)
  • 66% reduced risk of intracranial hemorrhage (HR: 0.34; 60 vs. 186 events)
  • 28% increased risk of gastrointestinal bleeding (HR: 1.28; 623 vs. 513 events)
  • No statistical difference in acute myocardial infarction (HR: 0.92; 285 vs. 327 events)

The study also found the following secondary outcomes:

  • 14% reduced risk of mortality (HR: 0.86; 603 vs. 744 events)
  • No difference in all hospitalized bleeds (HR: 1.00; 1,079 vs. 1,139 events).

Dabigatran is approved to reduce the risk of stroke and systemic embolism in patients with NVAF; for the treatment of deep venous thrombosis (DVT) and pulmonary embolism (PE) in patients who have been treated with a parenteral anticoagulant for 5 to 10 days; and to reduce the risk of recurrent DVT and PE in patients who have been previously treated.

Dabigatran 150 mg twice daily is the only oral anticoagulant to demonstrate superior reduction of ischemic stroke compared with warfarin in patients with NVAF. Dabigatran also demonstrated a similar rate of major bleeding events. Ischemic strokes are the most common type of stroke that NVAF patients experience.

The efficacy and safety of dabigatran in NVAF were established in the large RE-LY trial (N = 18,113). The study showed that, compared with well-controlled warfarin (n = 6,022), dabigatran 150 mg (n = 6,076) significantly reduced the risk of stroke and systemic embolism by 35% (primary efficacy endpoint: 134 [2.2%] vs. 202 [3.4%] events, respectively; HR: 0.65; P = 0.0001); ischemic stroke by 25% (103 [1.7%] vs. 134 [2.2%] events; HR: 0.75; P = 0.0296); and hemorrhagic stroke by 74% (12 [0.2%] vs. 45 [0.8%] events; HR: 0.26; P < 0.0001). The rate of all-cause mortality was lower with dabigatran 150 mg than with warfarin (3.6% per year vs. 4.1% per year, respectively).

Treatment with dabigatran 150 mg led to a 59% reduction in intracranial hemorrhage compared with warfarin (38 events vs. 90 events, respectively) and showed numerically lower rates of fatal and life-threatening bleeds (28 vs. 39 and 179 vs. 218, respectively).

Dabigatran was associated with a higher rate of total GI bleeds (6.1% vs. 4.0%) and major GI bleeds (1.6% vs. 1.1%; 50% increased risk with the 150-mg dose) compared with warfarin.

Source: Boehringer Ingelheim; November 3, 2014.

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