Coaguchek INRange ...

[bece13]

Hello everyone,
I had Mitral Valve replacement surgery 3 month ago and after reading lots of posts here I decided to buy my own Coaguchek INRange (available at Pharmacy in Canada) about 4-5 weeks ago.
Since then I compared results with LifeLabs and always get a difference of 0.8-0.9 which looks a bit high. I talked to Roche and they sent me new strips and standard calibration (test) solution and it came spot on at 1.9 They don't know why this difference and said they raised the issue with their World Office. I'm not aware of any disease that will influence the tests.
I talked to my GP and he is a bit puzzled as well and he tends to trust the lab more as he said that is highly regulated here in Ontario/Canada. However, reading on Roche website, they said that differences between any labs could be 1.0 at a true value of 3.0 (that means 2.5-3.5) this is a bit discouraging as my INR needs to be 2.5-3.5
My next step would be next week to compare LifeLabs to my INRange and to Couaguchek XS (some pharmacies here offer test on the spot with a request from Family Physician)
In the meantime, I would appreciate any suggestions anyone might have.
Here are my readings

Year	Month	Day		LifeLabs	INRange	Warfarin (mg)
2021	6	22	Tu	2.7		7.5
2021	6	23	We			7.5
2021	6	24	Th			7.5
2021	6	25	Fr			7.5
2021	6	26	Sa		3.7	7.5
2021	6	27	Su			7.5
2021	6	28	Mo			7.5
2021	6	29	Tu	2.3	3.2	7.5
2021	6	30	We			8
2021	7	1	Th			8
2021	7	2	Fr			8
2021	7	3	Sa			8
2021	7	4	Su		3.9	8
2021	7	5	Mo			8
2021	7	6	Tu	2.6	3.4	8
2021	7	7	We			8
2021	7	8	Th			8
2021	7	9	Fr			8
2021	7	10	Sa		3.6	8
2021	7	11	Su			8
2021	7	12	Mo			8
2021	7	13	Tu			8
2021	7	14	We	2.3	3.1	8
2021	7	15	Th			8.5
2021	7	16	Fr			8.5
2021	7	17	Sa			8.5
2021	7	18	Su		3.8	8.5
2021	7	19	Mo			8.5
2021	7	20	Tu	2.6	3.5	8.5

Thank you

 

[dick0236]

Welcome to the forum. No, there should not be a .8 or .9 INR difference between lab or home meter......more like .1 or .3.....even if your lab is using vein blood draws and not finger sticks. I have never heard of a Coaguchek lINRange meter. there was a meter used in the USA called INRatio (I think that was the name) a few years ago but it was recalled from the market several years ago. I would get the pharmacy to test you with their CoaguchekXS and the lab. Those INR readings should be within .1 or .2 or maybe even 0%. My guess is that the INRange is a bad meter??

 

[bece13]

The meter is Coaguchek INRange, they told me that is the new version of Coaguchek XS.
That is the plan to have a 3 way comparison within 30min difference: LifeLabs vs Coguchek XS (Pharmacy) vs Coaguchek INRange

 

[Lynn]

Welcome bece13. The large discrepancy in your INR results would be concerning to me. I have had a different experience with the Canadian Lab system. I live in B.C. and have compared my Coaguchek Inrange to both LifeLabs and our local hospitals lab. Life Labs has always been bang on. Not even a small difference from my meter. While the local hospitals lab has consistently been .1 to .3 below my meter.

Is there an alternative lab to Lifelabs locally that you could test at? If not I think your pharmacy idea is a good one. I think a third reading would be useful in helping you to determine which is the more accurate. Hope you get to the bottom of this so you can get an accurate handle on your INR, please keep us up to date.

 

[LondonAndy]

I agree with Lynn - an alternative lab test, or the pharmacy, seems a good plan. I have used the CoaguChek XS for 7 years and never had a discrepancy of more than 0.2 from my anticoagulation clinic's reading, whether they have used a blood draw or another meter. Personally, I am inclined to trust the meter more than the lab: the difference is occurring on multiple strips and from different batches, and given your tests with the test solution are on target that would seem to rule out the meter. I feel there is more that can go wrong in a lab test, maybe even down to storage or transport conditions between the clinic and the lab?

The INRange uses the same test strips as the XS, and I believe the basic unit to be the same - the difference is in having a colour display and a way to transmit results.

 

[bece13]

Thank Lynn
Yes there is another Lab in my area DynaCare, but first I’ll do the test with the pharmacy. I will post the results here.

 

[bece13]

Yes Andy, my thoughts exactly the same.
Another thing that came to mind are the batteries. The brand new Duracell batteries that came with the meter showed only 3 green bars on the meter instead of 4 (full batteries) and after a week it drop at 2 bars. So next week I’ll do 2 tests one with the current batteries and one with brand new ones to see if there is any difference.
And yes, you are right, they are using the same XS strips.

 

[Protimenow]

The issue with batteries MAY be worth checking out, but I suspect that meters are designed to give accurate results until there's insufficient power to run the test.

The XS has an issue with accuracy above 3.5 or so.

I've been using my XS almost exclusively for the past few months - although I've used the Coag-Sense for many years and trusted it more than I do now.

The difference between your lab's results and the meter's results looks like the lab took your blood from its vial and tested it on the Coag-Sense.

It would be interesting to see if your pharmacy's results are close to your meter's results.

 

[pellicle]

Hi

Since then I compared results with LifeLabs and always get a difference of 0.8-0.9 which looks a bit high.

seems like a bit much to me. However I'd look at the following points:

• are you strictly following all steps (no milking, 15 second rule, good blood sample, consistent methodology)
• are you sure that the labs are not somehow culpable here? They may be out by a small margin

Roche has this to say about compairsons with lab chemistry

also on this point:

this is a bit discouraging as my INR needs to be 2.5-3.5

its often the case that INR measurement is not a precise science and the reality is that if you only have one source then you just trust it ... but if you compare your watch to your phone you know they may be out from each other.

Once people see this for the first time they are anxious, but the reality is that this is why we have TARGETS (in your case INR=3) not a "RANGE" which misleads people to think that 2.5 is in range and so (even if its actually 2 or 1.9) they're OK

always aim for the target
let me consider this more

 

[bece13]

Thanks Pellicle

I read your blog as well as quite a few threads here.

Yes, I followed all the steps. I watched your video and doing it exactly the same. I tried once 2 tests within 5 min, one with the rubber and one without and I got exactly the same readings.

I agree, my target is INR=3.0 but on LifeLabs or INRange?

I read that document from Roche and I accept that could be small differences but 0.8-0.9 seems a bit much.

Roche even says the following:

"
In general, INR differences between POC devices such as CoaguChek systems and laboratory
systems are of the same order of magnitude as those observed between various laboratory
systems. There are no specific measurement differences between the CoaguChek
system and the laboratory. Measurement deviations are generally observed between different
coagulation measurement systems, independently of whether POC or laboratory.

The following points generally apply to measurement deviations:
Deviations are more common in patients with unstable anticoagulation, in whom coagulation
factors are even more variable. In addition, the likelihood of measurement differences
is increased further by different reagents sensitivities
In general, the higher the INR, the greater the possible deviations may be:

INR below 2.5: possible deviation 0.1 – 0.3 INR
INR 2.5 – 4.5: possible deviation 0.5 – 1.0 INR
INR above 4.5: possible deviation 1.0 – 2.0 INR
"
I guess I have to wait till next week when I'll compare LifeLabs vs Coaguchek XS (pharmacy) vs Couguchek INRange (my device)

If you have any other ideas let me know

Thanks again

 

[bece13]

Thanks Protimenow

I don't think Coag-Sense is available in Canada

I'll post the results next week.

 

[Protimenow]

I'm not suggesting you try Coag-Sense. I was just pointing out that some meters (and possibly labs) can have a somewhat sizeable variation. As Pellicle said, try to stay around your target INR.

FWIW - my last two tests with the XS, a week apart were almost exactly the same -- prothrombin time differed by a few seconds and reported INR was the same for both tests.

 

[pellicle]

Hi

In general, the higher the INR, the greater the possible deviations may be:

INR below 2.5: possible deviation 0.1 – 0.3 INR
INR 2.5 – 4.5: possible deviation 0.5 – 1.0 INR
INR above 4.5: possible deviation 1.0 – 2.0 INR

that seems reasonable, however in a document comparing XS and "Lab" we can see in this study:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1860570/

(trying to find my source document for that).


However from:
Accuracy of Capillary Whole Blood International Normalized Ratio on the CoaguChek S, CoaguChek XS, and i-STAT 1 Point-of-Care Analyzers
Brad S. Karon, MD, PhD,1 Robert D. McBane II, MD,2 Rajeev Chaudhry, MBBS, MPH,3 Lisa K. Beyer,1 and Paula J. Santrach, MD1

we see this ... which suggests 0.4 would be uncommon

from another document I note that there are potential client side issues:

Both POC instruments had higher INR variability in 4 disease states (antiphospholipid syndrome, autoimmune, peripheral vascular disease, and hypercoagulable).​

You don't have these do you?

If you have any other ideas let me know

the next obvious (to me) step is try an entirely different lab and see what they return. If that's greater agreement then I'd say that the lab was the issue. Such would not be the first time I've seen that.

 

[pellicle]

Here are my readings

just did a quick numbers on it and the differences are interestingly close; as you observe no more than 0.9 or 0.8 (you can tell I read this again for missed bits as PC is better than phone in this regard), (higher in the lab in all occasions). This makes me curious with such consistency what is at work here.

They don't know why this difference and said they raised the issue with their World Office. I'm not aware of any disease that will influence the tests.

I mentioned these above ...

Anyway, assuming this consistency is correct if your target is INR=3 then if you go with the Coaguchek for your INR you will be within the zone that's safe.

I look fwd to your answers to my questions on blood issues and the possibility of trying another entirely different lab (not a different branch of the same one).

Best Wishes

 

[pekster11]

i also have my own Coaguchek INRange meter
when i go for a blood draw at the lab, i will self test with the INRange meter about an hour before so a i can cross check results
i have never had a result from the INRange meter that was greater than 0.2 different from the blood draw result

Typically my INRange meter gives results that are slightly higher (~0.1-0.2) than the blood draw result analysed by the lab

 

[pellicle]

The brand new Duracell batteries that came with the meter showed only 3 green bars on the meter instead of 4 (full batteries) and after a week it drop at 2 bars

this is quite a drop ... I know another Australian with a INRange and it also chews batteries like a (guy I personally know from ) Kentucky (who was a US Navy) Sailor (and now drives big trucks in Japan).

 

[bece13]

Thanks Pellicle for all your time you put into helping me.

As far as I know I don't have any of those diseases or any other ones.

My plan is to compare Lifelabs vs Coaguchek XS (pharmacy) vs my INRange next Wednesday.
I will try to use the same batch of strips. Also I'll do a second test with brand new batteries in my device to see if there are any differences between half drain batteries and brand new ones.
IF XS results are the same as my INRange and 0.8-0.9 difference compare to LifeLabs, the following week I'll change the Lab and do the same test.
IF XS results are similar to LifeLabs (0.1-0.3) and different than my INRange (more than 0.4) I'll talk to Roche and ask them to send me another Coagucheck, XS if possible.

I understand that my Target INR=3.0 (therapeutic range 2.5-3.5) but 3.0 reading on my INRange will be 2.1-2.2 on Lifelabs which will take me out of my therapeutic range if LifeLabs is correct. On the other hand if I go with 3.0 from Lifelabs that will be 3.8-3.9 on my INRange which will take me out of my therapeutic range if my INRange is correct. So my biggest problem for me is not knowing what my true INR is, or which test is closer to the true INR value.

Hopefully I'll find out more next week.

One question: which of the out of range value for INR is better ( ), the higher one or the lower one (i.e. 2.0 or 4.0 with therapeutic range of 2.5-3.5)

Thanks Pekster11, it's good to know that other owners of INRange gets almost the same results as the lab.

FYI: my surgeon told me that they are using Coaguchek (most likely XS Pro) in the operating room
FYI: my Family Physician (GP) said that he tends to trust more LifeLabs as it is highly regulated here in Canada and they are required to do calibration tests quite often. My only concern here is that the testing lab where they analyze the blood sample is about 100km from their local lab where they only draw blood. I usually get the results in about 8 hours.

 

[bece13]

A bit of information about my story.
My mitral valve started to calcify because of a rheumatic fever not treated properly about 30 years ago when I was a kid. That lead to mitral valve regurgitation that lead to my atrium getting bigger and bigger which lead to AFib last year. I don't feel it but it shows on EKG, iWatch, Blood pressure monitor. Since then I'm on beta-blocker (metoprolol) to keep my HR under a 100. I had my Mitral Valve replaced with a mechanical one and my surgeon and cardiologist said that I might have a chance to get rid of it in max 1 year but most likely not as my atrium grew too much. We'll see. After the surgery my resting HR is around 52 and with effort never went more than 90. I might need to reduce the dosage for my metoprolol. Never had high blood pressure.

 

[Protimenow]

8 or 9 years ago, I trusted my InRatio enough to avoid doing lab validations (plus, I didn't have insurance to pay for labs.). The meter was giving consistent readings of 2.6.

I had a TIA - and the hospital labs showed a 1.6 or 1.7. I put too much trust in that damned meter.

After that, I ran tests on many different monitors - ProTIme, Protime 3, Coaguchek S, Coaguchek XS, Coag-Sense. I compared the results to lab results, and to the UCLA hospital anticoagulation clinic. The clinic used hemosense (I that's what it's called) - a tester that's used in operating rooms to test for INR and other issues.

I found, at that time, that the Coag-Sense seemed to be closest to the labs. The CoaguChek XS was usually slightly higher than the labs, and the average of the two meters often matched the lab results.

I also saw that the XS gave a higher reading as the actual INR increased.

I trusted the accuracy of the Coag-Sense. I trusted it to the point that, for a while, I assumed that LAB results were wrong when the Coag-Sense numbers were lower than the lab.

When I raised the issue of the Coag-Sense being about 1 below the XS and the lab, one of the support people saw this as a plus -- all I have to do is add 1 to the Coag-Sense number to get the correct number. Really. It's like adding an hour to a clock's time in order to correct its error.

For now, I've put the Coag-Sense on the backburner.

I've wondered about some of the medical issues that Pellicle pointed out as being possible sources of error in INR readings - and the Coag-Sense may be more sensitive to these issues.

If Pellicle hasn't already responded to your question -- it's much safer to have an INR ABOVE your target range than it is to have it too low. An INR that's too low could result in a TIA (as it did in me) or stroke, or possibly a pulmonary embolism. An INR that's higher than range just means that your blood will take a bit longer to clot. As long as the INR is below 5 or so, you should be fine.

 

[bece13]

Thanks Protimenow. That's what I thought, but wanted some more experience persons to confirm.