Is the Evidence for the Anticoagulant Rivaroxaban Valid? Interview with:

Dr. Deborah Cohen

Dr. Deborah Cohen

Dr. Deborah Cohen
Associate Editor BMJ
BMA House, Tavistock Square

Medical Research: What is the background for this study? What are the main findings?

Dr. Cohen: Anyone familiar with warfarin understands the critical role of INR values in determining the proper dose for warfarin patients. The INR value in an individual patient is the most important piece of information a doctor considers when determining the warfarin dose. If the doctor gives too little warfarin then the patient may be at undue risk of stroke; if too much, the patient may be at undue risk of a major bleed.

The BMJ investigation revealed that the INR device used to manage the ~7,000 warfarin patients in the ROCKET trial (which served as the basis for approval of the non-valvular atrial fibrillation indication) was defective.

As such – doctors were relying upon a defective device in determining the dose of the warfarin patients – which has a direct influence on the stroke and bleeding risk in that patient. Since this was a comparative trial – any deficiency in the performance of the comparator arm (warfarin) would skew the results in favour of the study drug (rivaroxaban).

Since INR directly influences strokes and bleeds – the primary efficacy and safety endpoints – it very much questions, if not undermines, the overall results of this trial.

Medical Research: What should clinicians and patients take away from your report?

Dr. Cohen: Patients should talk to their doctor about what to do next. Doctors should demand a full and transparent accounting of the exact nature and scope of the problem from the regulators and the makers of rivaroxaban.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Cohen: This is all about transparency. It is simply unacceptable for defects like this to be discovered by the press and not the regulators who are charged with policing these medicines or the drugs companies who sell them.

As explained in detail in my piece, all the information necessary to discover this problem was in the possession of global health authorities as well as Janssen – part of Johnson and Johnson – and Bayer.

I firmly believe that if there was greater transparency in clinical trial data that instances such as this could have been detected sooner.

Also, as Guido Rasi, the executive director of the European Medicines Agency, has said there is a need for further independent study of this whole class of drugs. Which drug in the class is safest and most effective and how well do they compare to well controlled warfarin?


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Dr. Deborah Cohen (2016). Is the Evidence for the Anticoagulant Rivaroxaban Valid? 

Last Updated on February 6, 2016 by Marie Benz MD FAAD