Meters 'don't work' for everybody ??? -- Values are always higher than lab?

[Protimenow]

I've been able to get actual blood draws during the past two months, and have used my meter an hour or less before the blood draws so that I can compare the meter to the lab results.

My meter is consistently higher than the lab results - always within 30%, but always higher.

Up until a couple months ago, I haven't had the luxury of comparing meter results with blood draws (except for one time in 2010 that confirmed that my ProTime meter was an almost exact match). After I got the InRatio, I found that it was much easier to use than the ProTime, but now I'm not so sure of how close it correlates to actual lab values.

I was told by a tech specialist that for some people, some meters just don't work. The reagents in the strips doesn't work properly with the person's blood -- and results aren't as accurate as they are for other people.

My recent experience suggests that my InRatio results are ALWAYS higher than those from the lab, and seem to be telling me that, if I want to be in a range of 2.5-3.5, I should shoot for a 3.0 on my InRatio.

I'll be trying a new lot of strips soon, and see if the results are different for a new lot.

I'm wondering, though:

Have any of you had similar experience with your meter's reported INR CONSISTENTLY being higher (or, perhaps, lower) than a lab's reported INR?

Have any of you heard that the blood from some people doesn't work properly with a particular meter?

 

[catwoman]

It's not a matter of "some meters just don't work," it's probably dependent on a medical condition.

http://www.valvereplacement.org/for...311-INR-Lab-vs-Office-Machine-amp-Thalassemia

However, I would assume that doctors would have already found this by now, if this applied to you.

Also, I would shoot for 3.5 with the INRatio, if your home results are always higher. Then you should have registering a comfortable INR result in the lab.

 

[Protimenow]

Yes, I'm shooting higher....and a few months ago there was a thread with a formula for converting InRatio - reported INRs into lab values. This assumed that InRatio is always higher than the lab - and that it was a predictable variance.

My plan is to shoot higher - and continue to go a bit higher - so that I can always be in range.

Except for the last two months or so, I haven't really had any 'doctors' involved my management - and recent bloodwork does NOT indicate thalessemia. My unfortunate experience with Quercetin strongly suggests a problem with the way that the InRatio tests for anticoagulation.

When I can afford some cuvettes, I'm strongly considering a return (if only partial) to my 'old' ProTime meter, or a move to a different meter that hasn't yet been discussed on the forum. These meters seem to use actual physical clotting for testing -- rather than electrical changes in the blood.

 

[chaconne]

This is an interesting question. I'm planning on buying a meter in the next few weeks. Does anyone know if there are related differences between the Coagucheck XS and a blood Draw?

 

[catwoman]

Does the doctor who manages your anticoagulation therapy use POC monitors or blood draws? That is the big question to answer.

Because my first INR tests post-op were on POC monitors, I have luckily escaped the debate/argument over which is "correct," a POC monitor or the old-fashioned lab blood draw. In the last 9 years, I only know of one time I have had a lab draw for an INR. That was 5 years ago when I was having a TEE. Yes, I have been spoiled!

I am surprised at how many cardio and other doctor offices eschew using POC monitors for lab draws. Lab draws have their place, when a patient's INR is extremely high and a POC monitor might be less sensitive, but all in all, POC monitors have been proven to be highly effective and accurate. Many anticoagulation clinics run by CACPs use monitors rather than blood draws. POC monitors provide the immediate ability to discuss any needs for dosage adjustments, to answer the patient's questions, to let the patient raise questions, etc. Sure beats having to wait for a callback on an INR test result and it going to your voicemail, then playing telephone tag.

Read some of the studies on POC monitors -- there are stickies here, and also check out resource materials at www.acforum.org (anticoagulation forum). This is the body that certifies CACPs. I've seen some of the test questions, and it's pretty comprehensive.

 

[Gail in Ca]

When my coumadin clinic wanted a yearly lab test of my INR, it was right in my expected range of 2.7, that I had been getting with the Coaguchek XS. My weekly results with my machine (Coaguchek XS) had been 2.4 2.7 2.8 2.7, then the lab-2.7, then the next weeks, 2.9 2.4 2.6, etc. All in range and the lab results just fine with what I had consistantly been getting at home. I really love this meter.

 

[Bina]

This is an interesting question. I'm planning on buying a meter in the next few weeks. Does anyone know if there are related differences between the Coagucheck XS and a blood Draw?

The Coaguchek XS monitor's acceptable variance to a blood draw is .2

Of course even lab blood draws can be a tad "off" because of mishandling of blood sample, different reagent used, etc. but there is
an acceptable variance for a reason, and we have an INR range for a reason. It is not always a precise measurement.

My Coagucheck XS has been testing my INR perfectly for the past 5 years with an occasional blood draw matching nicely.
Buy it, you won't be sorry.

 

[Protimenow]

I'm not sorry that I got an InRatio machine -- but I DID have an issue in the past with an OTC medication apparently throwing the meter's reading off. I tested it a few times, and my INR was consistently .6 or more higher than the lab value. (I was going along, blissfully believing that anything under 3.0 was good - and my 2.3, 2.4 or similar values that were slightly below range were no problem). However, the actual values were somewhere below 2.0 -- after my stroke, the hospital lab got 1.7. I think that there may be some things that we can take that might actually fool the meter into reporting values that are considerably more than .2 or .3 off.

It's also been reported, as noted, that blood draws are used to verify high INRS - 3.5 or above - because meters don't handle high INRs as accurately as they handle INRs that are in range.

I'm still planning to use my InRatio, but keep the INRs in the 3.0-3.5 area, if possible. I plan to soon get some ProTime cuvettes for parallel testing. (I am pretty sure that, although more of a pain to use, the ProTime may actually provide values that are closer to the lab values)

 

[ElectLive]

The Coaguchek XS monitor's acceptable variance to a blood draw is .2

Not to discredit the Coaguchek XS, which seems to be one of the best, if not the best, around, but the variance numbers they quote on their "Professionals" website are not as reassuring:

This CoaguChek page (http://www.coaguchek.com/com/index.php?target=/en/professionals/further_information/faq/6) mentions possible deviation as follows: 0.1-0.3 for INR < 2.5 | 0.5-1.0 for INR 2.5 to 4.5 | 1.0 to 2.0 for INR > 4.5. It also says that in general deviations up to +/- 20% are not unusual. Surprising to me was the middle category, potentially affecting those with a 2.5 -3.5 range. Not surprising, since emphasized often here, the upper category variance is dramatic and only adds to the strong argument for always double-checking with blood draw at the higher end.

An outside analysis of CoaguChek XS performance (http://www.coaguchek.com/resource.php?id=Resourcefile-6576494b8e3296faf&f=UkZJTEU2NTc2NDk0YjhlMzI5NjAxNi5wZGY=) that is referenced on the CoaguChek site (http://www.coaguchek.com/com/index.php?target=/en/professionals/further_information/correlation_studies_and_evaluations) indicates that 97% of values were within the industry (ISO) +/- 30% standard (seems kind of low for a standard, huh?). More meaningfully, though, it breaks it down further into the following approximate (there were multiple sets and test strip lots, as well as both blood methods, so I'm just doing a quick eyeball average - see the actual publication for full details) capillary based percentages for INR values less than 4.5: 98% of values were within +/- 30% deviation | 95% of values were within +/- 20% deviation | 67% of values were within +/- 10% deviation. So, the good news is that the Coaguchek goes well beyond the standard, the bad news is the the standard isn't that demanding.

Anyway, the big question to me also, back to how this thread began, is how the poor variance results actually present: broadly or more concentrated in certain patients. In other words, Bina, you could be one of the majority of patients who see not only good, but even better results than this data indicates. Perhaps it is only the minority of patients who just don't get good results (due to some form of blood disorder) and the extra variance just clouds the overall results. It seems to me someone (Roche, etc) would have figured this out in a little more detail by now, though, but that could be said about many things in the world of valve replacement I guess...

 

[Bina]

Not to discredit the Coaguchek XS, which seems to be one of the best, if not the best, around, but the variance numbers they quote on their "Professionals" website are not as reassuring:

This CoaguChek page (http://www.coaguchek.com/com/index.php?target=/en/professionals/further_information/faq/6) mentions possible deviation as follows: 0.1-0.3 for INR < 2.5 | 0.5-1.0 for INR 2.5 to 4.5 | 1.0 to 2.0 for INR > 4.5. It also says that in general deviations up to +/- 20% are not unusual. Surprising to me was the middle category, potentially affecting those with a 2.5 -3.5 range. Not surprising, since emphasized often here, the upper category variance is dramatic and only adds to the strong argument for always double-checking with blood draw at the higher end.

An outside analysis of CoaguChek XS performance (http://www.coaguchek.com/resource.php?id=Resourcefile-6576494b8e3296faf&f=UkZJTEU2NTc2NDk0YjhlMzI5NjAxNi5wZGY=) that is referenced on the CoaguChek site (http://www.coaguchek.com/com/index.php?target=/en/professionals/further_information/correlation_studies_and_evaluations) indicates that 97% of values were within the industry (ISO) +/- 30% standard (seems kind of low for a standard, huh?). More meaningfully, though, it breaks it down further into the following approximate (there were multiple sets and test strip lots, as well as both blood methods, so I'm just doing a quick eyeball average - see the actual publication for full details) capillary based percentages for INR values less than 4.5: 98% of values were within +/- 30% deviation | 95% of values were within +/- 20% deviation | 67% of values were within +/- 10% deviation. So, the good news is that the Coaguchek goes well beyond the standard, the bad news is the the standard isn't that demanding.

Anyway, the big question to me also, back to how this thread began, is how the poor variance results actually present: broadly or more concentrated in certain patients. In other words, Bina, you could be one of the majority of patients who see not only good, but even better results than this data indicates. Perhaps it is only the minority of patients who just don't get good results (due to some form of blood disorder) and the extra variance just clouds the overall results. It seems to me someone (Roche, etc) would have figured this out in a little more detail by now, though, but that could be said about many things in the world of valve replacement I guess...

EL, Yes, I did forget to mention that the "acceptable variance of .2" is for INRs under ~ 4.5 thanks for the reminder.
(After so many years of sharing the same info over and over again, I'm getting slack)
Higher INR readings do tend to show an increased variance but I have never had an INR over 4.3 so I have never needed to verify
that possible variance with a back to back blood draw.

I'm a very satisified poker

 

[Scott]

My inr has not been stable. I use the coagucheck. It doesnt bother me too much that the coagucheck isn't very accurate at higher ranges. It just tells me that I need to eat more greens if its a little high and maybe skip a dose if its really high.

 

[Protimenow]

I'm still a bit concerned when at the lower end of the range, the InRatio gives me an 'in range' message, but a blood draw doesn't. I rarely go into the high ends of the range.

I'm planning to use my ProTime meter - which uses a much different method of detecting INR - to see how close the InRatio and ProTime come to each other's results. (I may also do my test with Quercetin, and see if the ProTime meter is also 'fooled' by the medication).

Of course, I'll eventually get some lab blood draws to confirm the values from both meters.

 

[Julian]

Lab draw INR 1.5 in morning. After work went home did home monitor check in evening INR 2.0. Looks like I'll be shooting for 3.0 on home monitor from now on. Get lab tested guys, I'd say one every 3 to 4 months to gauge difference between home and lab. Just my .02

 

[Luana]

It's not a matter of "some meters just don't work," it's probably dependent on a medical condition.

http://www.valvereplacement.org/for...311-INR-Lab-vs-Office-Machine-amp-Thalassemia

Thanks, Marsha, that was my first thought, too. There may be some other blood disorders that make a venous draw more reliable than a fingerstick, but I was advised by someone who knows his stuff about INRs and testing that with thalassemia, which I have, it's best to have a venous blood sample.

 

[catwoman]

Thanks, Marsha, that was my first thought, too. There may be some other blood disorders that make a venous draw more reliable than a fingerstick, but I was advised by someone who knows his stuff about INRs and testing that with thalassemia, which I have, it's best to have a venous blood sample.

Luana:
Yup, I thought of you and had to hunt for the thread about thalassemia.

 

[Protimenow]

Now I'm even more stumped than I was a week ago.

I had expected that my ProTime meter would be pretty close to lab values. I was finally able to get cuvettes (the ProTime word for 'strips') last week. I did parallel testing between the InRatio, the ProTime3 and the lab. The InRatio gave me a 3.5. Nice. I figured that my INR was actually around 3.0. The ProTime gave me a 2.4 -- this was a bit of a surprise. I didn't expect to see THAT MUCH difference between the meters.

The blood draw, taken a few hours later, was a 2.95. This was pretty much right in the middle of the two meters.

So -- which do I trust? According to Alere, the blood draw is the one to be believed. I'm inclined to agree. What's troubling is the low value reported by the ProTime meter.

I'm considering (though not seriously) testing with the InRatio and the ProTime and using an average to suggest the actual lab value. If I had a LOT of money, and the cost of strips and cuvettes weren't an issue, I might even consider this strategy.

I plan to do another pair of tests on Friday. (I don't plan for a blood draw for many weeks). It'll be interesting to see how the two meters correlate.

Here's the issue -- if the meters can be so far off for me -- what happens in clinics or doctor's offices that rely on these things to be accurate?

 

[DanielB]

Intesting disicussion. I received my Inratio2 about six weeks ago. At that time I was headed for a pacemaker implant and a sternum wire removal surgery so I decided to stay with my medical groups regular testing, which is a finger stick unless the result drops below 1.8 for my 2.0-3.0 range, at whioch time they do a blood draw. A few things to mention, for what it's worth, as I am so new at this, so far I have tested from home and done six comparisons to the doctor/hospital tests, my Inratio has been exactly.1 higher than the both the finger sticks and one lab draw when I dropped really low (how is another story, not related to what we're talking about here). Due to all the surgeries and other factors my usual stable INR has seen a low of 1.2 (yikes!) to a high of 3.9 with stops in between. Again, in all cases, the Inratio has been .1 higher than the doctor's office and the hospital. This even with my blood count being below par which the Inratio manual says can skew the results.

I like the idea of keeping the range toward the high end when home testing as I agree with the motto of it's easier to replace blood cells than brain cells.

 

[Protimenow]

For a long time, I was a strong believer in using the meters. I still am.
With a problem a few months ago, and having been told by an Alere rep to 'trust the lab,' I'm a bit concerned that, for some of us, certain meters may just not work. Or, perhaps, if they are CONSISTENTLY a certain amount of points higher than the labs, I can certainly accept that. (It's kind of like living on the West Coast and using a watch set for East Coast time. If you know that your watch is ALWAYS 3 hours ahead, it's fine to use it. If I knew that my meter was ALWAYS .6 higher than the labs, I could certainly use that result).

However, I'm not sure yet that the difference can be reliably predicted.

For now, I'm content with trying to be sure that my INR is reported to be in range (on my InRatio, that probably means 3.0 or higher, and on my ProTime, it may actually be a bit below 2.5 or higher).

 

[Bina]

Intesting disicussion. I received my Inratio2 about six weeks ago. At that time I was headed for a pacemaker implant and a sternum wire removal surgery so I decided to stay with my medical groups regular testing, which is a finger stick unless the result drops below 1.8 for my 2.0-3.0 range, at whioch time they do a blood draw. A few things to mention, for what it's worth, as I am so new at this, so far I have tested from home and done six comparisons to the doctor/hospital tests, my Inratio has been exactly.1 higher than the both the finger sticks and one lab draw when I dropped really low (how is another story, not related to what we're talking about here). Due to all the surgeries and other factors my usual stable INR has seen a low of 1.2 (yikes!) to a high of 3.9 with stops in between. Again, in all cases, the Inratio has been .1 higher than the doctor's office and the hospital. This even with my blood count being below par which the Inratio manual says can skew the results.

I like the idea of keeping the range toward the high end when home testing as I agree with the motto of it's easier to replace blood cells than brain cells.

The majority of us using home monitors have that same degree of reliability with our testing.
My Coaguchek XS tests the same as my hospital lab.
Enjoy

 

[Marty]

INRatio vs hospital lab

INRatio vs hospital lab

The majority of us using home monitors have that same degree of reliability with our testing.
My Coaguchek XS tests the same as my hospital lab.
Enjoy

Much to my discomfort my wifes cardiologist insists on checking out the INRatio that we both use every six months against the hospital lab.. We have now done this three times. He says if it varies over .5 he will not allow her to use it. So far all three tests have been inside .5.