Thursday, June 18, 2009

Factor V Leiden testing not useful?


I was at morning report about 6 months ago after hearing a talk from the Leiden people. It turns out they had never intended the testing to be used the way it has in the US.

In fact, it seems for the last few years, everywhere you turned, every doctor was doing genetic testing......this time not for Hemochromatosis, which, again is not particularly useful as a screening test for disease state. This given the low penetrence and of the disease in those who have the mutations (Which is once again why DTC HFE testing is silly)

This time it was for Prothrombotic state with Factor V Leiden and GP20210A mutations/polymorphisms.

Why did we do this? Well, we ere taught that having these mutations put these patients at risk of having Deep Vein Thrombosis. Even perhaps that we give aspirin or blood thinners to these patients to PREVENT DVT etc......

In fact companies sprang up offering DTC thrombosis testing. It was actually one of DNA Direct's first offerings, before they wisened up and got into the clinical genetics business. But after this my guess is healthcare plans may balk at their advice to do Thrombophilia testing....So much for letting genetic counselors guide test management.....

But back to my story....

At morning report, I posed a question to the residents........
"What piece of evidence exists that indicates that we should be doing genetic testing for patients who have had DVT or Pulmonary Embolism?"

They were shocked at my answer........

"There are really no good studies which make me want to do genetic testing!"

"What?" they said. They even argued that I was wrong! Vehemently.......finally it is nice to see what I said have some teeth. Imagine that, a gene guy arguing against genetic testing.

Did you see? AHRQ, the research organization that is part of the Department of Health and Human Services.....(to be read as the comparative effectiveness organization)

Well, they find, upon reviewing 7777 titles and including 124 studies, they find..........

No direct evidence that testing for these mutations leads to improved clinical outcomes in adults with a history of VTE or their adult family members. The literature supports the conclusion that while these assays have high analytic validity, the test results have variable clinical validity for predicting VTE in these populations and have only weak clinical utility.

And we are talking Odds Ratios of 10 here guys and gals

Heterozygosity [odds ratio (OR) =1.56 (95 percent confidence interval (CI) 1.14 to 2.12)] and homozygosity [OR=2.65 (95 percent C.I. 1.2 to 6.0)] for FVL in probands are predictive of recurrent VTE. Heterozygosity for FVL predicts VTE in family members [OR=3.5 (95 percent C.I. 2.5 to 5.0)] as does homozygosity for FVL [OR=18 (95 percent C.I. 7.8 to 40)].......

So I really think we need to be very serious in analyzing our clinical utility of genetic tests......

Whether SNP scan or Genome or Single Molecular test.....The Government is on to this molecular game now......they will not rest until all waste is removed from their system. When insurers see what the government is doing they are likely to follow.

Which means we will begin to see even bigger claims of BU11$H!T out of marketing folks to overcome the overwhelming "MEH" coming out of the US Government and the physicians......

It is just good medicine to look at clinical utility of a test before ordering it. Which is why I predict only bad doctors will not heed the call of AHRQ here and why I still maintain MDVIP is practicing bad medicine by integrating a test with no current clinical utility into the care of their patients....

Stop the partnership Ed, I beg you.......

The Sherpa Says: I am completely unsurprised about this as I have been avoiding the hypercoag genetic work up lately. After the scientist from Leiden said that this was a ruse.....I began to wonder how many millions insurers had paid for this testing.......Thousands get PEs every year, even more get DVTs.......Maybe resource management would be better through Generation Health than DNA DIRECT

2 comments:

Alberto said...

Dear Dr. Murphy,
I remember I have studied on lecture notes some conditions in which to ask for a screening on trombophilia, such as first episode of DVT (age < 45), recurrent DVT without risk factors, DVT during pregnancy and many other.
Do you know which is the major ebm reference on this topic?
The review on FVL that you have linked is huge and too specialistic for a student I think. I just read on the abstract that there is some week clinical utility.
I was thinking that in the list of situations in which ask for screening, I have "asymptomatic people with parents with known thrombophilia condition". I would like to know what you think about this and if you could give me some tips to study this issue better. Knowing the carrier state of a mutation could bring for example a woman in avoiding contraceptive pills / smoking / any other risk factor, and doing so prevent a first DVT event. Thanks for letting me look more deeply on this topic.

Steve Murphy MD said...

Alberto,
Upon the pretty full review by AHRQ. It is clear that there is little advantage. But, the evidence is lacking

http://www.ncbi.nlm.nih.gov/pubmed/19151859?ordinalpos=6&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum

FYI,
-Steve