Dabigatran superieur aan warfarine, onafhankelijk van INR
Dabigatran superior to warfarin irrespective of INR control
Patients with atrial fibrillation (AF) have fewer strokes and bleeding events when taking dabigatran than when treated with warfarin, even if their international normalized ratios (INRs) are strictly controlled, shows further analysis of the RE-LY study.
The RE-LY (Randomized Evaluation of Long-term Anticoagulation Therapy) study, which included 18,113 AF patients, originally found that twice-daily dabigatran 150 mg prevented more strokes than did warfarin and had a similar safety profile, whereas the 110 mg dose was noninferior in terms of stroke prevention but had a better safety profile.
The latest analysis shows that "dabigatran is not simply superior or noninferior to warfarin because of poor INR control," said Deirdre Lane and Gregory Lip (University of Birmingham, UK) in a commentary accompanying the research paper.
Control of INR varied widely among the 951 study centers, with the average time their patients spent within the therapeutic range of 2.0-3.0 (TTR) ranging from 44% to 77%.
Overall, the finding of superior stroke and embolism prevention with dabigatran 150 mg and noninferior prevention with the 110-mg dose versus warfarin remained consistent after accounting for centers' average TTR, Lars Wallentin (Uppsala University, Sweden) and team report in The Lancet.
TTR also did not interact with the relationship of intracranial bleeding with dabigatran versus warfarin. But TTR did influence the relationship of major bleeding with treatment allocation, with event rates similar for patients given dabigatran 150 mg and those given warfarin by a center that maintained a high average TTR, but higher among warfarin-treated patients from centers with poor TTR maintenance (bottom quartile; TTR <57•1%).Major bleeding rates were lower with dabigatran 110 mg than warfarin irrespective of TTR.
Lane and Lip commented: "This finding suggests that dabigatran 110 mg has a better safety profile irrespective of the centers' quality of INR control, whereas the safety benefit of dabigatran 150 mg might only be evident when INR control is poor."
They went on to suggest that patients at low bleeding risk could be given the 150 mg dabigatran dose, in view of its superior embolic protection relative to that of warfarin, while patients at high bleeding risk could benefit from the improved safety profile of the 110 mg dose versus warfarin without losing embolic protection.