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Ross

Well-known member
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Dec 15, 2001
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Hello Brendan, nice to see someone from the company come aboard.

I'll ask a question that's on everyones minds that is using the INRatio.

Why do we have to maintain an INR of 3.1 or higher from the tests on the INRatio to score at least a 2.5 at the lab? I know .6 is the window, but I'm running a consistent .7 between what I get on the meter and what the lab draw gets.
 
I agree with Ross. For example, in the ER yesterday, my INR was 3.7 which is fine for me because my range is 3.0-4.0. I don't even worry if I am closer to 4.5 because I have a mechanical mitral and a-fib so I want my INR to be high.

Using my INRatio today, my INR was 4.3. One could argue that it is a day later and thus the difference but there is always a .5 or so difference and the INRatio is always higher than the lab tests.

It's not a big deal for me because I know about it now but it was an issue and concern when I first started using it. I know other new users have the same issue.

Welcome to our world.
 
I'll chime in with more of the same. I have my range set to 3.0-4.0 for this very reason. There was an inquiry in October by the FDA sent to Hemosense with regard to this but Hemosense never responded adequately. I also emailed them about the consistent difference, and they never responded. Maybe Brendon can get some kind of answer as he deals in higher volume than anyone single user.
 
Your questions

Your questions

Greetings All:

Thank you all for your warm welcome. I have just recently joined HemoSense and am in the process of learning a lot about the PT/INR industry as well as the INRatio monitor. In fact, it was while conducting searches on Google to learn more about the industry that I found this site and began to read some of the forum messages. In doing so, I felt that this is an excellent site that I should be a part of and decided to register. However, I?m not yet prepared to start answering product performance questions, but hope that in time I may be able to be a point of reference and insight for your questions. Until then, I feel that I must defer your questions to HemoSense Technical Support.

1-877-436-6444 x4 OR [email protected]

I?m a very customer focused person so I do hope that I can be more interactive with your questions down the road.

Thanks for your understanding.

Brendan
 
Hey Brendan, tell tech support to sign up! :D

Welcome to the group, what you don't learn at work, you'll learn here, I swear to it. ;)
 
Add my name to the list of INRatio users who have had a difference in the results from my machine vs. a lab draw. I tested myself last Wednesday and my INR was 2.9. At the ER on Thursday, using a lab draw, it was 2.2. Hopefully, the INRatio is the correct number because 2.2 is a little too close for comfort for me. LINDA
 
Ross said:
Why do we have to maintain an INR of 3.1 or higher from the tests on the INRatio to score at least a 2.5 at the lab? I know .6 is the window, but I'm running a consistent .7 between what I get on the meter and what the lab draw gets.

Let me thank everyone for their patience regarding a response to this question. My background is extensively in blood glucose and even though I thought the answer may be similar figured that waiting would be the best approach.

While it's natural to desire to see the same number on your INRatio as the lab it is not likely to happen for several reasons. One reason that that WHO allows for a +/- 20% variation is due to the introduction of small minute variations between the tests. Keeping in mind that there are numerous user factors that can affect the result from technique, to various blood related components. Keep in mind also that you're testing on two different devices (one designed for home use) the other for lab use. To illustrate this point it should be noted that even between lab instruments you will find variations. This link goes to pdf file that demonstrates this point.

http://www.hemosense.com/support/downloads/TechBulletin103_INR_and_ISI_revA.pdf

Note that along the bottom axis are individual patients and along the side axis is the INR result plotted by the different lab instruments. Thus, even in a scientific setting lab machines will give different results. So, who is right? It's really impossible to answer that question. The best approach is to work with your Doctor and understand the relationship and coorolation. As long as you're always .6 higher you and your doctor can have a discussion regarding this. Should this number shrink or become larger that would be a "Flag" of sorts to possibly explore any changes that may have occured.
 
Brendan our problems happen when Doctors look at the results and see that .6 variance, then come off with "Your machine is not accurate enough" and some have turned down home testing for this reason. We, as users of the INRatio know that to score a normal INR in the lab, we must maintain the high end of our range on the meter. New people won't know this though and it scares them when their doctors begin questioning the accuracy of the tests.

I just think you, as a Representative of HemoSense should be aware of what were experiencing in the field. ;)

By the way, don't know if this can be confirmed, but I was told that the thromboplastin used in the strips are a more sensitive European thrombosplastin and that may be the reason for the differences. Don't know that that holds any water, but it had me thinking.
 
Ross said:
Brendan our problems happen when Doctors look at the results and see that .6 variance, then come off with "Your machine is not accurate enough" and some have turned down home testing for this reason. We, as users of the INRatio know that to score a normal INR in the lab, we must maintain the high end of our range on the meter. New people won't know this though and it scares them when their doctors begin questioning the accuracy of the tests.

I just think you, as a Representative of HemoSense should be aware of what were experiencing in the field. ;)

By the way, don't know if this can be confirmed, but I was told that the thromboplastin used in the strips are a more sensitive European thrombosplastin and that may be the reason for the differences. Don't know that that holds any water, but it had me thinking.

Ross:

Yes, we understand this occurs and we know the importance of the patient and physician being on the same page. HemoSense is spending a lot of energy on education and awareness of anti-coagulation therapy and the benefits of home PT/INR testing. Of course, that doesn't mean that we'll be able to convince every physician. FWIW, there are still physicians that don't push regular testing of glucose for type II diabetes. They tell their patients eat right and exercise and you'll be just fine.

Again, I would discourage you from generalizing that all INRatio users need to keep in the "high end" on INRatio assuming that the INRatio is "low" vs. a "true" result. I say this because depending upon the lab equipment and all the various possibilities of testing error that can occur a different patient my have a completely different experience with INRatio. Some patients may even see very close results on their INRatio compared to the lab. What IS important is that each patient works with their physician to understand their specific PT/INR results and how to manage their particular case of anti-coagulation therapy.

Brendan
 
I know (or assume) we use a different machine to you - We use coaguchek S for Chloe but have the exact same issues every time we do venus vs coaguchek, no matter how close together we try and do the bloods they always come up 0.6 lower on venus than on coaguchek. Consequently, I have to agree with Ross and others and I keep Chloe's INR to the higher end of her range of 3-4. I prefer it closer to the 4 mark.

Good luck making some sense of it! lol

Emma
xxx
 
You know Emma, this is what kills me. INR was supposed to level the playing field between different labs and thromboplastin ISI indexes, but that's not what I'm seeing.
 
HemoSense-Brendan said:
Ross:Again, I would discourage you from generalizing that all INRatio users need to keep in the "high end" on INRatio assuming that the INRatio is "low" vs. a "true" result. I say this because depending upon the lab equipment and all the various possibilities of testing error that can occur a different patient my have a completely different experience with INRatio. Some patients may even see very close results on their INRatio compared to the lab. What IS important is that each patient works with their physician to understand their specific PT/INR results and how to manage their particular case of anti-coagulation therapy.

Brendan

Point taken. I'm only citing what appears to be a uniform thing amongst the INRatio users in this forum. I realize everyone is different, it's just that most all of us have to score a 3.1 or better on our units or the lab tells us were out of range on the low side.
 
HemoSense-Brendan said:
As long as you're always .6 higher you and your doctor can have a discussion regarding this.


HemoSense-Brendan said:
Again, I would discourage you from generalizing that all INRatio users need to keep in the "high end" on INRatio assuming that the INRatio is "low" vs. a "true" result. I say this because depending upon the lab equipment and all the various possibilities of testing error that can occur a different patient my have a completely different experience with INRatio. Some patients may even see very close results on their INRatio compared to the lab.

So, in other words, you would discourage Ross from suggesting that people keep their range on the 'high end', but you would encourage people to stay .6 higher than the low end.:confused: :confused: :confused:

Cris
 
Ross said:
it's just that most all of us have to score a 3.1 or better on our units or the lab tells us were out of range on the low side.
I'm one of those folks who tends to score about 0.5 to 0.6 high in the INRatio than the lab tests. Even with the admitted +/- 20% on INR testing, the medical community relies heavily (rightly or wrongly) on lab tests as the "gold standard". I set my range on the INRatio to be 3.0-4.0 to keep from getting the "OVER RANGE" message too often. The FDA is aware of the discrepancy http://www.fda.gov/foi/warning_letters/g5503d.htm and hopefully Brendan and Hemosense are working on a fix to get better agreement. It might be something as simple as recalibrating the strip codes or needing a software upgrade in the units. (Brendan, are they flash upgradable on the user end, or would they have to go back to the factory? I would guess the latter.) Being aware of the difference, I'm still more comfortable home testing than less frequent checks at the doctor's office.
 
Cris N said:
So, in other words, you would discourage Ross from suggesting that people keep their range on the 'high end', but you would encourage people to stay .6 higher than the low end.:confused: :confused: :confused:

Cris


Actually, I'm only suggesting that patients work with their physicians to understand what range they want them to stay in based upon their experience with comparing INRatio results vs. their lab equipment. As the Jacobson data indicated, even labratory devices vary from each other when compared to each other using the same sample. Thus, it's safe to believe that a home device will vary from the lab too.

It should be noted that some people experience results on their INRatio that are very close to their lab! I get the sense that some people don't want to believe that, but they really do! Don't just assume that your INRatio reads high or low based upon someone else's experience. WORK WITH YOUR PHYSICIAN and follow his/her direction.

Hope that clarifies
 
Interesting...

Interesting...

I have to check w/Nathan to be sure, but I think his coumadin clinic wants him higher as well with his INRatio....they don't want him falling under 3.0. He was actually closer to the lab draws that the clinics Pro Time machine. I will have to double check w/him to make sure I am relaying this right.
 
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