Lawyers for patients suing Johnson & Johnson and Bayer over the safety of the anticoagulant drug Xarelto (rivaroxaban) say that in a letter published in the New England Journal of Medicine, Duke University researchers left out critical laboratory data.
Lawyers asked a judge to unseal documents in the case, which involves more than 5,000 lawsuits filed by patients and their families who claim Xarelto harmed them. Five hundred suits involve patient deaths, the New York Times reports.
Editors at the New England Journal of Medicine say they did not know that separate laboratory data existed until a reporter contacted them, but the editors dismissed the data’s relevance and said they stood by the article’s analysis, according to the Times.
Xarelto—sold by Johnson & Johnson in the U.S. and by Bayer overseas—is the best seller in a new class of anitcoagulants seeking to replace warfarin, a drug with a sixty-year history. Blood thinners are prescribed for patients suffering from atrial fibrillation (irregular heart rhythm) and to prevent blood clots, deep vein thrombosis (DVT) and pulmonary embolism in patients undergoing knee or hip replacement surgery.
Xarelto and other drugs in its class have been marketed as more convenient than warfarin because the newer drugs do not require the regular blood testing and dietary restrictions imposed on warfarin users.
Duke Clinical Research Institute ran the three-year clinical trial involving more than 14,000 patients that led to Xarelto’s approval by the Food and Drug Administration (FDA). The trial compared the number of strokes and bleeding events experienced by patients taking Xarelto with those in patients using warfarin. But some experts are concerned that a faulty blood-monitor device may have led doctors to give patients the wrong dose of warfarin, which could have favored Xarelto in trial results. Last month the Duke researchers published an analysis in the New England Journal of Medicine and concluded that the problems with the device did not change the trial’s results. But some researchers say a better way to evaluate the device’s accuracy is to compare the device readings with test results done at a central laboratory. The investigators say they did that at two points in the trial, drawing blood from more than 5,000 of the patients taking warfarin and sending the samples for testing. The blood was taken 12 and 24 weeks after patients enrolled in the trial.
The Duke researchers made no mention of the lab data in their letter, however. The New England Journal of Medicine editors said in an interview that they did not know about the lab data until a reporter for the Times asked about it. Dr. Jeffrey M. Drazen, editor in chief, disputed the claim that the editors had been misled about the data, and said it was not relevant to the letter that was published.
Dr. Steven Nissen, a cardiologist at the Cleveland Clinic, served on the FDA advisory panel that approved Xarelto in 2011. Nissen was one of two panel members who voted against Xarelto approval, but he expressed doubt that an after-the-fact analysis would yield answers, according to the Times. “Given the fact that the device was inaccurate, there is no way anybody can tell you what would have happened in the trial,” he said.