My own experience is opposite of yours. About one year ago I purchased an INRatio2 and test weekly at home, but I have to go to my docs office monthly(his insistence) for his lab tech to test with a Coagucheck XS.....and I use that day to check my monitor against theirs. Of my last 14 tests(lab vs home over the past year) the Coagucheck XS has read above the INRatio2 eleven times, usually +.2, below one time, -.3 and 0 difference two times. Since both meters test close to each other, I am comfortable that both meter are pretty accurate.
A DIFFERENT Meter - Coagusense
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My own experience is opposite of yours. About one year ago I purchased an INRatio2 and test weekly at home, but I have to go to my docs office monthly(his insistence) for his lab tech to test with a Coagucheck XS.....and I use that day to check my monitor against theirs. Of my last 14 tests(lab vs home over the past year) the Coagucheck XS has read above the INRatio2 eleven times, usually +.2, below one time, -.3 and 0 difference two times. Since both meters test close to each other, I am comfortable that both meter are pretty accurate.
Does your doctor's lab tech send the blood out to a lab (or, perhaps, run it from the tube using a different meter?). If the tech is using a different meter, this may not prove a lot. If he stores the blood improperly, the lab results could also be somewhat less than accurate.
However, having your results closely reflecting those of your doctor's method (whatever it is), is good enough for me, too. Just try to stay in range (on either meter), and you should be fine.
However, having your results closely reflecting those of your doctor's method (whatever it is), is good enough for me, too. Just try to stay in range (on either meter), and you should be fine.
The past few weeks, I've stopped (not necessarily completely consciously) testing with the CoaguChek XS. My test a month ago, using the Coag-Sense was very close to the hospital lab. I expect that my results from a test yesterday will also be close to the lab's results. I'm testing weekly, but for the past few weeks only on the Coag-Sense (although I have adequate supplies for CoaguChek XS, InRatio and Protime meters).
At this point, I seem to have found a meter that I'm most comfortable with the results of. It seems to diverge considerably less than the CoaguChek XS and InRatio when my INR is at or above the top of my range, and it seems to slightly underestimate the lab results when I'm near the bottom of my range -- effectively helping me to stay IN range.
I'm not quite ready to get rid of the CoaguChek XS -- especially because I know that strips will be available for many years to come -- but, to me, the InRatio and InRatio 2 are too wildly inaccurate as to be of little diagnostic use to me. (And, if the ProTime testing was less of a hassle, I may try it some more, too).
At this point, I seem to have found a meter that I'm most comfortable with the results of. It seems to diverge considerably less than the CoaguChek XS and InRatio when my INR is at or above the top of my range, and it seems to slightly underestimate the lab results when I'm near the bottom of my range -- effectively helping me to stay IN range.
I'm not quite ready to get rid of the CoaguChek XS -- especially because I know that strips will be available for many years to come -- but, to me, the InRatio and InRatio 2 are too wildly inaccurate as to be of little diagnostic use to me. (And, if the ProTime testing was less of a hassle, I may try it some more, too).
latearrival
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Coaguchek XS INR readings systematically and significantly too high
Coaguchek XS INR readings systematically and significantly too high
Hi
This is a really informative discussion! I just joined the forum so I could post my experience in case it might be of interest to anyone else that might stumble across the thread the way I did...
I have a Coaguchek XS which I've been using for the past two years to manage my own warfarin dosing (with my cardiologist's blessing once I'd proved I knew enough to do so). I assumed the XS was accurate enough for guiding my dose change decisions. The device is small, quick and easy to use and I love it. However, I recently had a lab INR test and I was able to do my own test a few hours later with the XS. A difference of +0.8 (Lab 3.5, Coaguchek 4.1) worried me and so I've been collecting comparison data once a week for the last 6 weeks.
Here's my data (lab test and self-administered Coaguchek XS tests done no more than 2 hours apart, usually less than an hour):
Lab XS Difference
3.5 4.3 +0.8
3.0 4.1 +1.1
3.0 3.5 +0.5
3.0 3.7 +0.7
3.4 4.0 +0.6
2.6 3.1 +0.5
3.0 3.4 +0.4
As you can see, my Coaguchek XS is systematically higher than the lab (an average of 0.66).
Most worryingly, this difference is enough for me to have made the wrong dosing decision (e.g. decreasing my dose when I should have been maintaining it) on 5 out of the last 7 weeks if I had relied on the Coaguchek XS result. Looking at my last two years of Coaguchek XS INR results I have probably been below range (2.5 to 3.5) for 60-70% of the time. Lucky I haven't had a stroke!
This quote sums things up for me:
I wish either my cardiologist or surgeon had advised me of this when I first got the machine. It would also have been nice if Roche Australia's Customer Service, when I spoke to them, didn't try and fob me off by implying that their devices are infallible.
(As an aside, have any of you tried testing your 'significant other' with your machine? I think it would be interesting to see if their INR = 1.0).
Coaguchek XS INR readings systematically and significantly too high
Hi
This is a really informative discussion! I just joined the forum so I could post my experience in case it might be of interest to anyone else that might stumble across the thread the way I did...
I have a Coaguchek XS which I've been using for the past two years to manage my own warfarin dosing (with my cardiologist's blessing once I'd proved I knew enough to do so). I assumed the XS was accurate enough for guiding my dose change decisions. The device is small, quick and easy to use and I love it. However, I recently had a lab INR test and I was able to do my own test a few hours later with the XS. A difference of +0.8 (Lab 3.5, Coaguchek 4.1) worried me and so I've been collecting comparison data once a week for the last 6 weeks.
Here's my data (lab test and self-administered Coaguchek XS tests done no more than 2 hours apart, usually less than an hour):
Lab XS Difference
3.5 4.3 +0.8
3.0 4.1 +1.1
3.0 3.5 +0.5
3.0 3.7 +0.7
3.4 4.0 +0.6
2.6 3.1 +0.5
3.0 3.4 +0.4
As you can see, my Coaguchek XS is systematically higher than the lab (an average of 0.66).
Most worryingly, this difference is enough for me to have made the wrong dosing decision (e.g. decreasing my dose when I should have been maintaining it) on 5 out of the last 7 weeks if I had relied on the Coaguchek XS result. Looking at my last two years of Coaguchek XS INR results I have probably been below range (2.5 to 3.5) for 60-70% of the time. Lucky I haven't had a stroke!
This quote sums things up for me:
I wish either my cardiologist or surgeon had advised me of this when I first got the machine. It would also have been nice if Roche Australia's Customer Service, when I spoke to them, didn't try and fob me off by implying that their devices are infallible.
(As an aside, have any of you tried testing your 'significant other' with your machine? I think it would be interesting to see if their INR = 1.0).
I'm sorry, but not surprised to see that your lab and meter exhibit so much variance. I'm also glad to see that your INR, according to a lab, didn't fall below 2.6.
It's most worrisome when the meter shows a value between 2.0 and 2.5 - in my experience, it often means that your actual INR is around 2.0, and possibly even below 2.0. It was reliance on the accuracy of my earlier meter (I won't say which one, but anyone who watches my postings knows which one it is) that made me comfortable with a 2.6, not realizing that my INR was more like 1.7 or 1.8.
It's also reasonable to expect that, as the INRs get higher, the amount of error between lab and meter (CoaguChek XS and InRatio) increases.
In my case, I am most comfortable with my CoagSense meter, and haven't always confirmed the value against the CoaguChek XS. My CoagSense seems to slightly under-report, so an INR of 2.0-2.5 on this meter is not particularly worrisome to me. I would much rather be ABOVE the LOW END of my range than slightly above the high end. For me, it seems easier to deal with a bit of extra bruising or bleeding than it is to deal with the possibility of a stroke.
I'm glad to see that you're learning to relate your meter's values with the lab values. (One other thing -- lab values may not always be particularly reliable, either - there are factors relating to reagent management, sample handling, and other things that could cause variants in the lab's results. I personally trust a local hospital's lab results but, just for reference, found that there was a significant difference between hospital lab and a clinic lab on blood taken within hours of each other. The lab's accuracy may not be absolute, either).
Yes, I've tested a 'significant other' on various machines and the results ranged from 0.9 to 1.1 on the meters that I've used.
It's most worrisome when the meter shows a value between 2.0 and 2.5 - in my experience, it often means that your actual INR is around 2.0, and possibly even below 2.0. It was reliance on the accuracy of my earlier meter (I won't say which one, but anyone who watches my postings knows which one it is) that made me comfortable with a 2.6, not realizing that my INR was more like 1.7 or 1.8.
It's also reasonable to expect that, as the INRs get higher, the amount of error between lab and meter (CoaguChek XS and InRatio) increases.
In my case, I am most comfortable with my CoagSense meter, and haven't always confirmed the value against the CoaguChek XS. My CoagSense seems to slightly under-report, so an INR of 2.0-2.5 on this meter is not particularly worrisome to me. I would much rather be ABOVE the LOW END of my range than slightly above the high end. For me, it seems easier to deal with a bit of extra bruising or bleeding than it is to deal with the possibility of a stroke.
I'm glad to see that you're learning to relate your meter's values with the lab values. (One other thing -- lab values may not always be particularly reliable, either - there are factors relating to reagent management, sample handling, and other things that could cause variants in the lab's results. I personally trust a local hospital's lab results but, just for reference, found that there was a significant difference between hospital lab and a clinic lab on blood taken within hours of each other. The lab's accuracy may not be absolute, either).
Yes, I've tested a 'significant other' on various machines and the results ranged from 0.9 to 1.1 on the meters that I've used.
Last week, I said that I expected that the results of a test on my Coag-Sense would be pretty close to the hospital lab. It was.
Coag-Sense: 3.8
Hospital Lab: 3.63
This is the first time that the Coag-Sense reported slightly higher than the lab -- but neither method is perfect.
I've changed my diet slightly, ogne back to my regular daily dose, and am now back in range. Because the hospital isn't comfortable with my INR being above range for both blood draws, I'll be getting another draw next week -- and it WILL be back in range (I'll confirm this on my Coag-Sense before I go to the lab).
At this point, although I still have plenty of fingertips available for testing, I am testing almost exclusively using the Coag-Sense meter.
It's too bad that they're not as readily available, or as well known, as the others.
Coag-Sense: 3.8
Hospital Lab: 3.63
This is the first time that the Coag-Sense reported slightly higher than the lab -- but neither method is perfect.
I've changed my diet slightly, ogne back to my regular daily dose, and am now back in range. Because the hospital isn't comfortable with my INR being above range for both blood draws, I'll be getting another draw next week -- and it WILL be back in range (I'll confirm this on my Coag-Sense before I go to the lab).
At this point, although I still have plenty of fingertips available for testing, I am testing almost exclusively using the Coag-Sense meter.
It's too bad that they're not as readily available, or as well known, as the others.
