NEW YORK (Reuters Health) – Patients with atrial fibrillation had a lower risk of hemorrhagic stroke with dabigatran than with warfarin in the RE-LY study, researchers say.
The risk of ischemic stroke was no different with one drug or the other, however.
In RE-LY, compared to warfarin, dabigatran 110 mg twice daily was associated with similar stroke and systemic embolism rates but lower rates of major bleeding, whereas dabigatran 150 mg twice daily was associated with lower rates of stroke and systemic embolism but similar rates of major hemorrhage.
“This post-hoc subgroup analysis published in Stroke provides strong support that compared to warfarin, Pradaxa (dabigatran etexilate mesylate) is a safe and effective treatment option when used as directed in Asian and non-Asian patients with atrial fibrillation,” Mary Lewis from Public Relations, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut told Reuters Health. “The findings from this subgroup analysis are also consistent with the findings from the pivotal RE-LY trial.”
Dr. Masatsugu Hori from Osaka Medical Center for Cancer and Cardiovascular Diseases in Japan and colleagues analyzed RE-LY patient data from 2782 Asians and 15,331 non-Asians.
As reported June 6th online in Stroke, non-Asians spent more time in the therapeutic INR range for warfarin (66.2%) than Asians (54.5%). The Asian patients spent less time above the therapeutic range (10.1%, vs 14.0% for non-Asians) and more time below the therapeutic range (35.4%, vs 19.8% for non-Asians).
Among Asian patients, the rates of stroke of systemic embolism per year were higher on warfarin (3.06%) than on dabigatran 110 mg BID (2.50%) or 150 mg BID (1.39%), but only the higher dose of dabigatran was associated with a significantly lower rate.
Results were similar, albeit with lower rates overall, for non-Asians (1.48% for warfarin, 1.37% for dabigatran 110 mg BID, and 1.06% for dabigatran 150 mg BID).
Hemorrhagic stroke rates on warfarin were significantly higher among Asian patients (0.75% per year) than among non-Asian patients (0.32% per year; p=0.007), but hemorrhagic stroke rates were much lower among dabigatran-treated patients in both groups.
“This is the first subgroup analysis to show that Asian patients experience a high rate of hemorrhagic stroke when taking warfarin,” Lewis said.
Compared with warfarin, major bleeding rates for Asian patients were 43% lower with dabigatran 110 mg BID and 43% lower with dabigatran 150 mg BID, and total bleeding rates were 52% lower with dabigatran 110 mg BID and 40% lower with dabigatran 150 mg BID.
“For total bleeding there was a statistically significant interaction between treatment and region (Asian versus non-Asian) indicating that dabigatran reduced the risk of bleeding outcomes more in Asians than in non-Asians,” the researchers note.
The net clinical benefit consistently favored dabigatran over warfarin in both Asians and non-Asians, but only dabigatran 150 mg BID was clearly superior to warfarin in Asian patients.
“The findings provide strong support that compared to warfarin, Pradaxa is a safe and effective treatment option when used as directed for Asian and non-Asian patients with AF,” Lewis said.
“The 110 mg dose of Pradaxa is not approved for use in the U.S.,” Lewis added.
Dr. Hori referred our inquiry to Boehringer Ingelheim Pharmaceuticals, which responded on his behalf.
Boehringer Ingelheim funded the study, provided consultancy fees for Dr. Hori, and employed one of the other 18 authors. Nippon Boehringer Ingelheim employed two other authors.