Coagucheck vs InRatio

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My Coaguchek has indeed worked perfectly in over 4 years of use and whenever I have comparison tested with the
hospital blood lab the results have been exactly the same.
The allowed variance according to Roche guidelines is .2
Sorry that I don't have any bridging experiences to share, but I don't foresee that as an issue anyway.

Thanks, Bina - that's a great data point. Sounds pretty accurate and reliable.

I just got off the phone with Alere support. They gave me an email address to escalate the questions to one of their staff physicians. The short answer was "No, you can't use INRatio strips during bridging, Lovenox is a known interferent, and the requested interval is a 24 hour wait period after stopping Lovenox." However, when I delved into the anti-factor Xa activity numbers, they decided to escalate the inquiry. I think the main question at this point is: is the use of INRatio strips during Lovenox bridging contraindicated due to lack of data, or because a specific study has indicated that it would be problematic. I'll report back on my findings.

Incidentally, I spoke with Donna, the technical support representative at Alere, and she was very nice and very helpful. The contact info for Alere is:

1-877-441-7440
tech support - press 2
for inratio - press 1

Best,
pem
 
I noted before that Alere's tech support was friendly and helpful. I think the InRatio insert suggests that testing when lovenox levels are UP TO 4 U/ml (that's units per millileter, rather than international units which are used for vitamins and other medications) should be okay to test.

However, it'll be good to see how long it takes Alere to respond to this question (which seemed to already be answered in their product inserts)
 
Way to go Pem!

Thanks for looking into all this. I would like to know the answer to this question.

Incidentally, I called my future anticoagualtion clinic at the Kaiser Permanente Los Angeles Medical Center. They are willing to work with home testers, and do, but they don't cover the cost of the meter. It sounded like they required home testers to use the INRatio2 meter. I asked the bridging accuracy question, but the person who called wasn't sure about it.

Them requiring the INRatio meter could mean they think it is the most accurate (even during bridging). It would be nice to get some real comparative data points.
 
I noted before that Alere's tech support was friendly and helpful. I think the InRatio insert suggests that testing when lovenox levels are UP TO 4 U/ml (that's units per millileter, rather than international units which are used for vitamins and other medications) should be okay to test.

However, it'll be good to see how long it takes Alere to respond to this question (which seemed to already be answered in their product inserts)

Hi protimenow!

Thanks for clarifying the use of "units" vs "international units".

It would certainly seem that way on the surface. The package insert indicates: "In Vitro studies show the Alere INRatio system to be sensitive to levels of heparin and low molecular weight heparin of 4 U/ml or greater. This test should not be used for patients on heparin therapy."

The first sentence indicates that INRatio is sensitive above 4 U/ml, but it doesn't make any claims about its sensitivity below that threshold, which would be a different claim. The second sentence sounds like a clear contraindication. So I'm wondering now if you've presented evidence that I've missed in support of the use of INRatio for bridging. Have I?

Thanks and best,
pem
 
Way to go Pem!

Thanks for looking into all this. I would like to know the answer to this question.

Incidentally, I called my future anticoagualtion clinic at the Kaiser Permanente Los Angeles Medical Center. They are willing to work with home testers, and do, but they don't cover the cost of the meter. It sounded like they required home testers to use the INRatio2 meter. I asked the bridging accuracy question, but the person who called wasn't sure about it.

Them requiring the INRatio meter could mean they think it is the most accurate (even during bridging). It would be nice to get some real comparative data points.

Kaiser, Alere, etc. requiring or encouraging the use of one meter over the other is purely for financial reasons.
It has absolutely nothing to do with the accuracy of the meter.

The American insurance companies and clinics tend to have a huge (~300% ) price mark up if clients purchase
their own meter from them. Here in Canada meters can be bought by patients outright. Price= $500.
Either meter will serve you well, Good Luck :)
 
Bina,

That very well may be true. I will press that point when I talk to the Kaiser clinic in the future.

Even so, at this point, I will need to see some real test data before I know what to believe about bridging accuracy.

On the other hand, since the need for bridging is rare, I may not end up making a decision based on this.
 
I have had my INRatio2 machine for 5 years now. Before I got my machine, I used to go to the hospital lab. Did that for 31 years, can you believe that!

Anyway, in the 5 years that I've had my home monitor, I have not had a lab draw to see how my INR readings compare to my finger sticks with my home machine.
Have any of you with home machines had a lab draw (vein draw) for comparisons? Would this be a wise thing to do, I wonder?

Just asking....?
 
N Jean - I haven't had a blood draw for comparison -- but two years ago, I got hit in the head by a dishwasher that I was helping load into a car. I got a mild concussion. I was taken to a local emergency room, and they did a blood draw - coming back with a 2.92. The day before, I did my regular weekly test using a ProTime 3 machine - and had a 2.9. I've moved from the ProTime 3 (still a good machine, but requiring a bit more blood and refrigeration of the strips) to an InRatio. I've made one or two comparison blood draws, and the meters were close - if not exact. When I had a really low INR a few months ago, and didn't want to eat up strips while I was getting my INR back into range, I did tests on my InRatio and CoaguChek S - and these results, too, were within a tenth of a point.

The FDA is pretty sticky about approving devices like these (there's a meter from ProTime that STILL hasn't gotten FDA approval, after more than a year) - so I'd be pretty confident in the results of any meter. There IS an issue with meter accuracy above an INR of 4 or so -- with high INRs, I've seen recommendations that the value be confirmed by a blood draw - but for INRs below 4 or so, I would personally be extremely comfortable with the results from my meter - whichever one I'm using.
 
Pem -- the only answer I can give you right now is that there is a difference in the action of Lovenox and Heparin. It's not contradictory to say that the test shouldn't be used for people taking Heparin and to say that people bridging with Lovenox can still do the test.

However, I'd still be concerned with testing using a meter if I'm taking Lovenox, without something more conclusive from my meter manufacturer. (It SEEMS as if you CAN get an accurate test if your Lovenox concentration is below 4 U/ml, according to the insert that I quoted).
 
N Jean - I haven't had a blood draw for comparison -- but two years ago, I got hit in the head by a dishwasher that I was helping load into a car. I got a mild concussion. I was taken to a local emergency room, and they did a blood draw - coming back with a 2.92. The day before, I did my regular weekly test using a ProTime 3 machine - and had a 2.9. I've moved from the ProTime 3 (still a good machine, but requiring a bit more blood and refrigeration of the strips) to an InRatio. I've made one or two comparison blood draws, and the meters were close - if not exact. When I had a really low INR a few months ago, and didn't want to eat up strips while I was getting my INR back into range, I did tests on my InRatio and CoaguChek S - and these results, too, were within a tenth of a point.

The FDA is pretty sticky about approving devices like these (there's a meter from ProTime that STILL hasn't gotten FDA approval, after more than a year) - so I'd be pretty confident in the results of any meter. There IS an issue with meter accuracy above an INR of 4 or so -- with high INRs, I've seen recommendations that the value be confirmed by a blood draw - but for INRs below 4 or so, I would personally be extremely comfortable with the results from my meter - whichever one I'm using.

Thanks for your reply.

When I first got the meter, I do remember that my doctor recommended I conduct two lab draws and compare them to the my monitor to test for accuracy. The results were almost identical and the dr was pretty impressed with the comparisons. Since then, however, I had not done anymore comparisons but I feel very confident w/my home monitor results.
 
I have had my INRatio2 machine for 5 years now. Before I got my machine, I used to go to the hospital lab. Did that for 31 years, can you believe that!

Anyway, in the 5 years that I've had my home monitor, I have not had a lab draw to see how my INR readings compare to my finger sticks with my home machine.
Have any of you with home machines had a lab draw (vein draw) for comparisons? Would this be a wise thing to do, I wonder?

Just asking....?
Hello Njean
Thirty-one years!!! That's staying power. My hat's off to you.
What is the state of your veins?

Following 3 years of vein draws my the vein in my left arm was crying for mercy. The vein in my right arm had been tied shut the result of right heart catheterization. Medical personnel never bothered to tell me and when I found out on my own I looked around for a better method of testing and found one--POC home monitoring. Had I known prior to valve replacement I would have chosen a tissue valve.

When I found a hospital that recommended home monitors I decided to get one and haven't looked back nor regretted my decision. The hospital enrolled me in a study to assess the safety and efficacy of POC requiring me to do a vein draw for comparison every 6 months. I think Roche prefers this for accuracy as well.

I don't think it would hurt to do it especially if your require a blood test for other reasons an INR could be done at the same time.

Once again--congratulations--31 years. It's hard to believe you have any veins left.
Sandra
 
I have had my INRatio2 machine for 5 years now. Before I got my machine, I used to go to the hospital lab. Did that for 31 years, can you believe that!

Anyway, in the 5 years that I've had my home monitor, I have not had a lab draw to see how my INR readings compare to my finger sticks with my home machine.
Have any of you with home machines had a lab draw (vein draw) for comparisons? Would this be a wise thing to do, I wonder?

Just asking....?


I have done the lab draw, home monitor comparison for 2 years. I test every two weeks at home and now go to lab once a month just to keep my doctor happy.
 
I have done the lab draw, home monitor comparison for 2 years. I test every two weeks at home and now go to lab once a month just to keep my doctor happy.

And how have they compared, Freddie? Is your lab draw a vein draw or finger prick like the home monitor?

The reason I ask is because when I compared the finger prick draw at another coumadin clinic I was asked to go, their INR readings did not jive w/my home monitor at all. It was the vein draws that were closer to my home monitor readings.
 
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Hello Njean
Thirty-one years!!! That's staying power. My hat's off to you.
What is the state of your veins?

Following 3 years of vein draws my the vein in my left arm was crying for mercy. The vein in my right arm had been tied shut the result of right heart catheterization. Medical personnel never bothered to tell me and when I found out on my own I looked around for a better method of testing and found one--POC home monitoring. Had I known prior to valve replacement I would have chosen a tissue valve.

When I found a hospital that recommended home monitors I decided to get one and haven't looked back nor regretted my decision. The hospital enrolled me in a study to assess the safety and efficacy of POC requiring me to do a vein draw for comparison every 6 months. I think Roche prefers this for accuracy as well.

I don't think it would hurt to do it especially if your require a blood test for other reasons an INR could be done at the same time.

Once again--congratulations--31 years. It's hard to believe you have any veins left.
Sandra

You know, Sandra, considering everything I've gone through in all these years, my veins have held up wonderfully. The doctors and nurses have always raved about what great veins I have! Thank God for that!
 
And how have they compared, Freddie? Is your lab draw a vein draw or finger prick like the home monitor?

My monitor has always been .2 or .3 higher than the vein draw. Only once has the lab been higher than my results, which was .2 higher.

Here's today's results: Monitor reading today was 3.0, vein draw was taken within an hour of doing home testing. Haven't received their results of vein draw yet, but going by pass results from the lab, their results will be 2.7 or higher but not over 3.0.
 
Pem -- the only answer I can give you right now is that there is a difference in the action of Lovenox and Heparin. It's not contradictory to say that the test shouldn't be used for people taking Heparin and to say that people bridging with Lovenox can still do the test.

However, I'd still be concerned with testing using a meter if I'm taking Lovenox, without something more conclusive from my meter manufacturer. (It SEEMS as if you CAN get an accurate test if your Lovenox concentration is below 4 U/ml, according to the insert that I quoted).

Protimenow,

Thanks. Until now, I thought the only difference between Heparin and Lovenox is that the former is given intravenously and the latter is given subcutaneously (those joyful belly shots). Thanks for clarifying that important distinction!

You wrote: "It SEEMS as if you CAN get an accurate test if your Lovenox concentration is below 4 U/ml, according to the insert that I quoted"

Are you referring to this quote: "In Vitro studies show teh Alere INRatio system to be sensitive to levels of heparin and low molecular weight heparin of 4 U/ml or greater." ? If so, I would be cautious about drawing such a conclusion. As an analogy, consider the following statement: "the road gets wet when it rains more than 4 inches per hour." Would you conclude from that that people don't get wet when it rains less than 4 inches per hour? Do you see what I'm getting at?

Anyway, thanks again for pointing out the difference between heparin and lovenox, especially for the purposes of interpreting the manufacturer's guidance!

Best,
pem
 
My monitor has always been .2 or .3 higher than the vein draw. Only once has the lab been higher than my results, which was .2 higher.

Here's today's results: Monitor reading today was 3.0, vein draw was taken within an hour of doing home testing. Haven't received their results of vein draw yet, but going by pass results from the lab, their results will be 2.7 or higher but not over 3.0.

As someone pointed out earlier - as long as the difference is consistent, then you have a reading you can work with, right? The question is, which one is the true INR? I suppose most people would assume the venous draw lab result is the gold standard, so you would always make an adjustment of -0.2 to your home reading for the purposes of adjusting dosage. Does that sound right?

Thanks,
pem
 
My monitor has always been .2 or .3 higher than the vein draw. Only once has the lab been higher than my results, which was .2 higher.

Here's today's results: Monitor reading today was 3.0, vein draw was taken within an hour of doing home testing. Haven't received their results of vein draw yet, but going by pass results from the lab, their results will be 2.7 or higher but not over 3.0.

Confirmed lab results for today is 2.9
 
Pem:

A couple answers:

First, I was referring to the statement that said (I'm paraphrasing) that you can't test if you're using Heparin. This, to me, sounded like it wasn't excluding Lovenox.

As far as your question about 'gold standard,' I'm not entirely convinced about how gold a standard the blood draw is, UNLESS the place where the blood is drawn also does the test on the blood, and usually does it without too much delay. Here's why: venous blood is put into a glass tube with a material that keeps the blood from coagulating. You don't really know how the blood is stored or handled between the time it's drawn and the time the lab tests it. Also - the labs use 'standardized' reagents, which cause the blood to coagulate, and from which the INR is determined. If the reagents aren't perfect - not perfectly set at the value that is established for them when the label is put onto the reagent container - there's a possibility that the INR value may be slightly off. Certainly, no reagent manufacturer would intentionally put anything other than the exact reagent value on its packaging, but it's possible that these values fall within a range of values -- so INRs may be tenths or hundreds of a point high or low when the testing is done.

By contrast, the strip makers produce large batches of test strips. An inaccurate code value (which is, I assume, a pretty exact value for the reagent used on the strip) could render results of testing with the strips to be inaccurate for a large group of users. Such an error would be, at the very least, embarrassing to the manufacturer, but could also expose them to lawsuits, could call their reliability into question, and could do a great deal of damage to the company -- and may even be dangerous for patients who rely on accurate results. I can't see a strip manufacturer NOT running multiple quality controls on their strips and reagents before shipping them - to do otherwise could be catastrophic.

That said, improper storage of the strips could, conceivably, cause slightly inaccurate results. This problem is probably mitigated by the existence of quality controls on the strips put out for the current machines from each test company (Roche, Alere, ITC).

I'm not entirely convinced that lab blood draws are necessarily a gold standard versus INR test machines. Either method will give you a pretty close picture of your actual INR. Perhaps there is no such thing as a 'true' INR. (INR is a ratio between the prothrombin time and the reagent value -- if the value of the reagent is slightly off, due to many factors, even in the lab reagents or the strip reagents, a reported INR might be slightly inaccurate)

In any case, if your INR is WAY out of range, it's a good idea to repeat the test (if this is a lab test) or to get a lab blood draw to confirm a troubling meter result.
 
As someone pointed out earlier - as long as the difference is consistent, then you have a reading you can work with, right? The question is, which one is the true INR? I suppose most people would assume the venous draw lab result is the gold standard, so you would always make an adjustment of -0.2 to your home reading for the purposes of adjusting dosage. Does that sound right?

Thanks,
pem


Lab technicians are allowed a .2 variance when testing INR. Once a blood sample is taken, 3 tests are perform and from that an average is determined. So lets say it's a good average than to say a lab draw result is the gold standard.

I do not adjust my dosage if I'm within my target range which is 2.5 - 3.5. Even if the lab came back with a result of 2.3 and my home monitor had a reading of 2.6

A true INR is only as true as when it was taken. INR can fluctuate throughout the course of the day. IMPO, INR however it is taken and what the result is; is a good average.
 
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