The future of the INR

Traditional anticoagulants such as warfarin and heparin prevent clot formation by interfering with the ability of proteins in the blood called clotting factors to function. Dabigatran is a new class of anticoagulants called thrombin inhibitors that work by interfering with the stage of clot formation, preventing the protein thrombin from converting fibrinogen to fibrin. So how will this affect the medical laboratory?
The warfarin industry is a billion dollar industry and part of the cost is constantly monitoring its therapeutic affect on the patient. The test used to monitor warfarin therapy is called the the INR (short for International Ratio). A low INR means that the dose is to low, there is an increased risk of clots forming. A high INR means there is a risk of uncontrolled bleeding. Both situations require time and resources to bring the INR back into a therapeutic range.
Since Dabigatran does not require any blood tests to monitor it, the INR could become obsolete, and with it the entire lab infrastructure that goes into doing this test.
This is not the first time an established anticoagulant therapy was replaced by a better replacement. For years a drug called heparin was used to treat blood clots. Like warfarin, it needed to be constantly monitored by a lab test called the APTT and had to be administered intravenously in a hospital setting. Then ten years ago Lovenox (also known as low molecular heparin), was released. It had the benefits of being injectable, not requiring constant
But if dagibatrin replaces warfarin as a treatment for the prevention of blood clots, the patient no longer needs to have any monitoring done, and the lab loses a client. Can you blame the patient though? No more having to go to the lab to be poked and prodded, over time veins become scarred resulting in it become harder and more painful to get blood specimens for the INR test. Dagibatrin has none of the dietary restrictions that warfarin has.
It stands as a testament to warfarin’s contribution as a cost effective way of improving people’s lives that it has taken over 50 years before a suitable replacement might be found.
How can labs face the challenges dabigatrin present?
Even if dagibatran replaces warfarin, it will not make it or the INR test obsolete. Like all drugs, dagibatran cannot be taken by everyone. Heartburn was the major non-bleeding related side effect, so severe that it had to be discontinued.
The long term affects of taking dagibatran have not been studied as well. How will the human body be affected by taking this drug for six months, 1 year 1 decade? Possible, dagibatran will have some minor side effects that will require some lab testing. An example of this would be how lipitor now requires liver function testing to be done.
Another side effect was there being a very small but statistically significant increase in the risk of heart attack for some patients. Why is still being investigated, but it could require some sort of lab test to screen patients that are in this risk group, possible a future gene test designed for this.
Even if the patient has none of the above problems, as with any anticoagulant therapy there is a chance of uncontrolled bleeding. It will be up to the lab to determine if the bleeding is due to dagibatran. This will be done by using either of two tests, thrombin time (TT) or ecarin clotting time (ECT). Medical labs will need to add these two tests to physicians if dagibatran use increases.
It is quite possible that warfarin may become obsolete, and this will have a huge impact on Medical Laboratories.
But it is only by understanding what these changes are and preparing for them that labs will be able to survive and even thrive.
Thank you for taking the time to read my posting. I look forward to your thoughts and comments.
Regards,

Mark Hawkins