Recently, the FDA issued a report, based in part on data from the questionable RE-LY study, stating that adverse events involving serious and fatal hemorrhaging caused by the anti-coagulant drug Pradaxa may have been somewhat exaggerated. The three authors of the report – none of whom have ties to the manufacturer – suggest that much of the bad news surrounding Pradaxa is due to the fact that it is a relatively new drug and therefore subject to more media scrutiny. Beyond that, however, the report states that, based on an analysis of the RE-LY study, rates of uncontrolled bleeding caused by Pradaxa is approximately the same as that caused by warfarin, which has been standard treatment since the 1950s.
The RE-LY study had some problems however, not the least of which were insufficient controls. Ideally, any scientific study involving comparisons between two medications requires that both researchers and subjects be completely unaware of whom is receiving what – until the results have been recorded. This was the case according to a letter from the University of British Columbia Health Sciences Department (published on the Therpeutics Initiative website in early 2011). Additionally, the lead researcher on the RE-LY study later disclosed that he had a “financial relationship” with Pradaxa's manufacturer, Boehringer-Ingelheim.
Now, Dr. Kevin McConeghy of the University of Illinois has said that, according to his own analysis of the data, rates of hemorrhaging due to Pradaxa are as far more than those caused by warfarin. Dr. McConeghy, who presented his data at the recent American College of Cardiology (ACC) 2013 Scientific Sessions, notes that patients treated with Pradaxa (dabigatran) were on the average older than those who had been taking warfarin (75 for the Pradaxa group vs. 68.5 for the warfarin group). There were other small, yet potentially significant differences between the two groups, which leads Dr. McConeghy to warn that his data “should not be used to draw any definite conclusions.”
Nonetheless, this has sent some conflicting messages about the safety of dabigatran – and it does not change the fact that, while bleeding from warfarin can be stopped with high doses of Vitamin K, there is as of yet no such antidote for the adverse effects of Pradaxa.
Hughes, Sue. “Mixed Messages on New Bleeding Data With Dabigatran.” Heartwire via TheHeart.org, 15 March 2013. Available at http://www.theheart.org/article/1519257.do.
N/A. “Dabigatran for Atrial Fibrillation: Why We Can Not Rely on RE-LY.” Therapeutics Initiative, University of British Columbia Department of Anesthesiology, Pharmacology and Therapeutics (January - March 2011). Available at http://www.ti.ubc.ca/letter80.
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