Friday, February 5, 2010

FDA, Warfarin, still not as sexy to me.

When everyone poo poo'd Warfarin, I became very, very upset. Here was a good clinical case for using PGx tests. Not a great case, but a good case. It was only when I began to think about feasability.

Lets face it, most decisions around starting coumadin happen in the hospital. Why?

Well, most patients receive an anticoagulation injection medication that most people have to be specially trained to administer at home versus a nurse in the hospital. Further, the rat poison known as coumadin is dangerous to take and is tricky to dose. So in the hospital is where a lot of people get titrated to the right dose.

This creates multiple problems

1. Insurers do not like paying for expensive meds like low molecular weight Heparin
2. Insurers do not like paying for extra hopsital days to dose a medication
3. Hospitals do not make any more money keeping people in the hospital to dose coumadin
4. Doctors do like to keep patients safe

This creates a market opportunity with demand.

But the question remains "Will testing get patients out of hospital quicker?"


Does this testing keep patients safer?


Will the FDA change the label?

They already did.

However, how many hospitals can run CYP2C9 and VKORC1?

Not very many.

What is the TAT?

Unless it is 24 hours it will not be that helpful.

Now as a Hospital, what is the ROI?
Now as a Insurer what is the ROI?
Now as a physician what is the cost of interpretation?

From a view point of a clinician who supports Personalized Medicine. We need to get rid of Coumadin and use Dabigatriban.

Is this testing useful? Yes. Is it clinically utilizable. If you are willing to wait a month.

Will this get quicker? Yes.

How much quicker? 2 weeks quicker.....but the fact remains, unless you can get a TAT of 12-24 hours this is not a reality in most worlds.....

The Sherpa Says: Great that the FDA notices the utility, but not great that the test is still too slow.


Unknown said...

look up iverson genetics. they turn around the warfarin genetic test in 24 hrs.

Kristine Ashcraft, Genelex said...

Turnaround in 24 hours could be offered by any lab doing genetic testing if volume justified it, but the notion that 24-hour TAT is needed is a fallacy. Genotype based dose adjustment should be made on day 4 or 5, not day 2. In the first few days, patients can be given a 5 mg dose because the levels have not reached steady state. Withouth genotyping you do not know if they will reach steady state on day 4 or 5 (CYP2C9 EMs), day 8-10(CYP2C9 *1/*2 IMs), or 12-15 days for the remaining phenotypes. This lack of information causes "oversteer" that can lead to dangerous bleeding events. Please take a moment to watch for more information on this.

Steve Murphy MD said...

Excellent video. Thank you. That being said, I do believe that doctors will not order this test until it is a 24 hour TAT.

Maybe you have a different market, but I know doctors. I agree that titration decisions should be made later on. Especially since we are talking about SS versus INR.......

However, the problem still exists.

All Hospitals should be equipped to perform this testing and should have 24 hour TAT. Why 24 hour TAT? Because doctors won't like to wait too long in anticipation.

For insurers, to say it will take 12 days for SS, they most likely would not pay for anything but discharge on day 3 with a lovenox bridge.

Insurers could drive the ship here. So could hospitals.

The fallacy is that doctors will order this testing without a prompt or 24 hour TAT......or without some good leadership.


Steve Murphy MD said...


Thanks. I know Dean Sproles. Great guy.

Misha said...

I think the more disturbing thing is that we've known that there is a relationship between genotype and warfarin for 45 YEARS. VKORC1 and CYP2C9 were cloned a long time ago. And yet we don't seem to be anywhere near consensus.

Steve Murphy MD said...

I totally agree. Here we are in the next century still debating this. I think partly this is due to the lack of education. But also, I blame this on the lack of research until now. Why are we only getting funding to do the studies now? WTF?