NEW YORK (Reuters Health) - Dabigatran and warfarin offer similar stroke-prevention efficacy in patients with atrial fibrillation (AF), but their side effect profiles differ, according to a systematic review and meta-analysis of real-world clinical practice.
"There could be many reasons for the differences in our findings, such as differences in the quality of evidence of observational studies and randomized controlled trials (RCTs) or differences in the included study populations between the observational studies in our review and the RE-LY trial," Dr. Robert J. Romanelli from Palo Alto Medical Foundation Research Institute, California, told Reuters Health by email.
The RE-LY trial is the only RCT to have evaluated dabigatran in stroke prevention, and RCTs are prone to selection biases less likely to be present in well designed observational studies, Dr. Romanelli and colleagues note in Circulation:Cardiovascular and Quality Outcomes, online January 26.
The team used data from seven retrospective cohort studies to compare the effectiveness and safety of dabigatran and warfarin among more than 348,750 patients with nonvalvular AF.
During an overall mean follow-up of 794 days, dabigatran 150mg or 110 mg was similar to warfarin in ischemic stroke prevention.
Both the higher and lower dabigatran doses had significantly lower hazards of intracranial bleeding compared with warfarin (pooled hazard ratio, 0.44 and 0.49, respectively). But the hazard of gastrointestinal bleeding was significantly greater for dabigatran 150 mg (but not for 110 mg) than for warfarin (pHR, 1.23). The 110 mg dose of dabigatran was only available during the trial; it's now sold in 150 mg or 75 mg capsules.
The increased risk of gastrointestinal bleeding with the higher dose of dabigatran was significant only in older populations (75 years or older).
"Data presented in this review reflect relative risk, which is not always clinically meaningful," the researchers caution. "It is important to bear in mind that event rates for the outcome of interest are low under standard treatment."
"I don't think the findings from this one reviewshould change clinical practice," Dr. Romanelli said. "If anything, this study revealed areas for future research.