Find one test method and stay with it? Pshaw

[Protimenow]

My initial reason for starting this thread was that therapeutic decisions are based on INR -- and if there was enough difference between INR based on testing, there could be a problem.

If my Coag-Sense gives me an INR of 3.1, and Coaguchek XS gives a 3.7, and the labs may give an even higher value - trusting the Coag-Sense and making no dosing changes should keep my INR in range. If I responded to the Coaguchek or the labs, I may lower my dosage - without knowing exactly if the reduction in dosage would drop the INR, as tested by the Coag-Sense, would be too high (maybe causing the INR reported by the Coag-Sense to get to 2.0 or lower).

If the difference between the Coag-Sense and the other test methods is a bit troubling -- if all agreed within, say, +/- .2 or .3, this wouldn't be an issue -- but with a difference of 1.0 or higher between Coag-Sense and other methods, dosing differences WOULD be applied, with a potential for moving a person's INR to the top or bottom of a safe range.

In this case, I'm not sure that I overthought this.

 

[Protimenow]

My goal in starting this thread WAS treatment intention.

My Coag-Sense was reporting around 1.0 below the CoaguChek XS, and even more below the labs. Given those differences, I was concerned that dosing changes, based on one test or the other, could actually result in INRs that are slightly above, or slightly below, range.

I'm not certain why the Coag-Sense reported INR is so different from the other methods -- the company stands firmly behind its accuracy. I'm sure that Roche and the labs do, too.

If the differences were trivial, any method would be fine for testing - and trusting. If all methods were within .3 or so +/- each other (as they were when I first started comparing meters and labs), I would have no issues with choosing and staying with any of the methods.

I don't really know which to trust for approximate accuracy. I'm again testing Coag-Sense against CoaguChek XS, and occasional blood draws. If the difference between meters and lab (lab and XS being 1.0 or more different from Coag-Sense), I can imagine a scenario where a high INR reported by CoaguCheck XS or lab would result in an adjustment that drops the INR (if you believe only Coag-Sense) out of the low end of the range. If the INR reported by the Coag-Sense is reported as low, slight increases in dosage could push the INR to a level at, or above the range as reported by lab or XS.,

I now have two sets of XS strips. I'll be doing comparative tests to validate each method.

It's still a matter of which method I can trust -- and it looks like I'll be out here on my own while doing it.

 

[pellicle]

and it looks like I'll be out here on my own while doing it

We are all always alone ultimately.

 

[Protimenow]

Yes, on one level, I guess we ARE all alone, but we can also be parts of groups -- lots of alone souls communicating (or not) with other lone souls. (And I still have trouble with the concept of 'soul')

With reference to this thread, I'm testing to see what's going on with two different meter technologies, and one or more labs. And, in this area of discovery, I think the group is down to one.

 

[Protimenow]

This is a sort of update.

For the last few years, I've trusted my life to the Coag-Sense meter. I've trusted it even though labs reported higher results than the meter. I think part of this trust is a statement from the then-CEO of Coagusense -- 'they always blame the meter.'

When I was actively comparison testing meters a few years ago, both the Coag-Sense and CoaguChek XS meters had values that were within .2 or .3 of the lab results, and pretty close to each other. I was confident in both meters - and chose to trust the Coag-Sense more than the Coaguchek XS because it reported slightly below labs, and I'm more comfortable with a result that is slightly below the labs to one that is slightly higher.

Since then, although repeated tests using the Coag-Sense were almost identical, the results seemed to be as much as 1.3 or 1.4 points BELOW the labs. I've also recently gotten some CoaguChek XS strips and am testing with them. My last few tests, I used both meters.

Two days ago, the Coag-Sense gave me a 3.1. A few minutes later, the CoaguChek XS reported 4.1. The next day, the hospital lab gave me a 4.2.

It seems to be becoming clear which meter should be trusted. I have probably 75 Coag-Sense strips, and the company stands behind the accuracy of their meters, but my doubts are escalating. Maybe they screwed up when testing their new strips. Maybe, for some weird reason, my blood clots too quickly for the meter to be accurate. I don't know.

I'll continue testing with both meters - as long as my XS strips hold out - and am aiming at a monthly blood draw as a control.

Maybe then my Pshaw will go away, and I'll have more confidence in one meter or the other - with monthly confirmations from blood draws.

 

[user 15848]

I use the XS as main tool for managing inr, but during the ccp-virus time not going out to labs for test, in pre virus times i would go once a month to the lab just reasurance that the differences tests show are within expected range or +/- 0.2; dont know about the other meter u mention here, only know about the coaguchek and lab

 

[Amy]

I'll continue testing with both meters

Hey, there , Protimenow. what ever happened with this? It’s been 10 months - have you figured out which meter to trust?

thank you.

 

[Protimenow]

Amy - I wish I had a definitive answer.

It may partially depend on the labs doing the tests, in addition to the meter's accuracy.

Most of the time, the CoaguChek XS is closer to the lab. Occasionally, it's run the other way. Years ago, I took an average of the two meters as a PROBABLE value.

It's a bit troubling - a 2.5 on my Coag-Sense may mean it's 3.5 on the XS - and, maybe, something close to 3.5 at the labs (which still puts me in a safe range).

I'm still using both meters - but it probably isn't all that necessary.

Perhaps I'm just wasting strips on both meters.
Perhaps whatever has happened to my blood that makes the Coag-Sense report lower than actual INR has resolved.

In any case, both meters are good. The XS may be a better choice for most people because strips are readily available, Roche isn't going anywhere (I'm not suggesting that Coag-Sense won't be around for many more years), and its reach is global.

 

[Amy]

Would it be an option for you to try a different lab? If there were any way of knowing which labs are more reputable than others...

 

[Protimenow]

I've done this in the past. A few years ago, a lab reported a 5.1. My meter had me, if I recall, at around 2.7. I had blood drawn at two different labs - all in the same day, and their results were slightly higher - low 3s.

I reported this to the doctor who told me about the 5.1, and he thanked me. He had another patient, whose INR was always stable, and always in range - and she, too, had a 5.1. Sometimes labs screw up.

INR testing is an art - values can fall within a 20% range and still considered to be accurate.

Right now, I'm stuck using a very large lab for my blood draws.

 

[Sheenas7]

Well I had to have some blood drawn the other day and my internist used Lab Core to check my INR.
I thought it would be a good time to check the outcomes with my Vantus Xs Coagu check. I was not fasting. He took my blood at 10 am or so. I went home and an hour later my machine read 3.4. The Lab Core result came in at 2.7. I was not happy that the were .7 appart!
Is that okay? Pellicle can you comment too?

 

[Protimenow]

Sheens7 - I've had to use Labcorp, too. Was the blood taken by your doctor and then picked up by Labcorp? Sometimes the blood is mishandled by the doctor's office before getting to the lab's courier.

I've found major differences between meter and lab many times.

In your case, although I'm not Pellicle, I would say that either meter is within range - I wouldn't worry too much about it. A test is considered to be 'accurate' when the value is 20% +/- the actual value. In your case, at the higher end of your result, it's accurate if it's as high as 32.6. In the case of Labcorp, the lower end of their range is 27.2.

In the case of these two measurements - accounting for the accepted variance from the test results, I'd say that you have nothing to worry about.

And the most important takeaway from this is that your INR is AT LEAST 2.7 - and probably higher, because the Labcorp test WAS higher than your meter.

 

[pellicle]

Sheena

I nearly missed this, and would have it this was not a quiet time and I was interested in following @Protimenows posts

if you don't reply to me directly or use an @ mention, then I'll get no notification. Type the @ character then without any space start typing the username, it may take a moment but it will suggest users after 3 letters are typed ...

Well I had to have some blood drawn the other day and my internist used Lab Core to check my INR.
I thought it would be a good time to check the outcomes with my Vantus Xs Coagu check.

I have no idea what a Vantus is, but I'll assume that's some amercian company redistributing Roche products and its a Roche Coaguchek

He took my blood at 10 am or so. I went home and an hour later my machine read 3.4. The Lab Core result came in at 2.7. I was not happy that the were .7 appart!
Is that okay? Pellicle can you comment too?

0.7 INR units is a bit more than I'd feel comfortable with but it isn't entirely outside the known possibilities. Firstly, please cast your eyes over this carefully and read the table with care:

you can see that for a reading of 3.0 on the Coaguchek that the reagent Thrombotest returned 2.76 and Innovin returned 3.56

This is a significant variation within these reagents (reagent is a fancy word for the chemical compound that's used to allow measurement)

You can see that the Coaguchek is between these values.

Now a lab is supposed to do some baseline checks to "tweak" their given result (with their reagent) back up to (probably) WHO guidelines (but I don't know what the USA {or even each state authority} uses). If they have not done the proper "baseline" procedure (because maybe they don't get audited much and who cares right?) then the results you get may be similar to what is in that table (from a Roche publication).

This underscores what I continue to harp about: INR is not a rock, its a bowl of jelly. Do not take measurements of it to be like using a micrometer to measure a piece of steel.

I harp about this because I consistently see people (OCD types) fussing about 0.1INR units and trying to skim the edges of their range. It is exactly because of this psychology that the later view of "Target" (not range) was introduced.

Now your Bio does not say if you have a mitral or an aortic (and I can't remember) so what I'd say is to go with your Coaguchek and if you're concerned about it go to a different lab (and ask them the question and a clear and direct way "I had a test somewhere else which gave me a different result to what I expected from another test on the same day, what reagent do you use in your INR testing"

Don't accept any fob offs or walk. That should get them to make sure that they baseline or you can at least compare to that chart.

Back to targets and jelly - I'd always advise staying in the middle of the INR Target as it currently is set by the Surgical Guidelines of your country (which are usually consistent internationally). Aim for the center of the target not the outside ring (which those trying to skim along at the bottom of their range do) and you will naturally account for any possible variances that exist and be in this all important range of outcomes

which according to what you've posted you actually are.

As to what I think you should do, I'd follow your Coaguchek and test again next week and see what that is ... follow up (with an @mention) if you get a result that is perhaps too high and maybe far away from what you want.

Best Wishes

 

[Amy]

@pellicle -

I’ve seen that graph a few times around these parts. I get that it describes the INR range of adverse events, the center of which we should aim for.... but what do the bottom numbers, below the graph mean exactly? I mean ‘pt years, events, incidence’. It’s not super clear to me, & I love being super clear.

Anyone who this is completely clear to, feel free to chime in! Thank you.

 

[pellicle]

but what do the bottom numbers, below the graph mean exactly?

the bottom numbers (the X axis) are small ranges of INR, so INR =1.0-1.4 and then INR = 1.5-1.9

The Y axis is the number of incidents per 100 patient years.

Obviously the less incidents the better, and its implicit that on the lower end of the X axis the incidents will be thromobsis related and on the upper end (right hand side) of the X axis the incidents will be bleed events

It makes the case that being higher than 2.4 but lower than 5.0 is the best range to be in to prevent indicents.

 

[Amy]

I mean ‘pt years, events, incidence’.

I mean
For example
It says ‘events, no.’ and ‘8’ across from 3.5-3.9.
What does that mean?
Sorry to be so stupid - I think I used to know what that referred to, but now I can’t recall.

 

[pellicle]

For example
It says ‘events, no.’ and ‘8’ across from 3.5-3.9.

the column heading is Events, No.

No. is commonly used to mean "the number of"
Events = the "events" which classified as an event (meaning a bleed or a thromobisis event"

 

[Amy]

Right.... I got all that... but that can’t mean there were eight adverse events at a 3.5-3.9 INR range, & only 1 for 1.0-1.4. So....... ? Anybody?...

 

[pellicle]

Right.... I got all that... but that can’t mean there were eight adverse events at a 3.5-3.9 INR range, & only 1 for 1.0-1.4. So....... ? Anybody?...

You need to look at the column Incidence per 100 patient years for the understanding of that data.

I guess you have no schooling in statistics (no shame in that, we are all born ignorant not everyone goes to university and does a degree).

It can and does exactly mean that.

Tell me then what you think patient years column means...?

 

[Sheenas7]

Sheena

I nearly missed this, and would have it this was not a quiet time and I was interested in following @Protimenows posts

if you don't reply to me directly or use an @ mention, then I'll get no notification. Type the @ character then without any space start typing the username, it may take a moment but it will suggest users after 3 letters are typed ...


I have no idea what a Vantus is, but I'll assume that's some amercian company redistributing Roche products and its a Roche Coaguchek



0.7 INR units is a bit more than I'd feel comfortable with but it isn't entirely outside the known possibilities. Firstly, please cast your eyes over this carefully and read the table with care:

you can see that for a reading of 3.0 on the Coaguchek that the reagent Thrombotest returned 2.76 and Innovin returned 3.56

This is a significant variation within these reagents (reagent is a fancy word for the chemical compound that's used to allow measurement)

You can see that the Coaguchek is between these values.

Now a lab is supposed to do some baseline checks to "tweak" their given result (with their reagent) back up to (probably) WHO guidelines (but I don't know what the USA {or even each state authority} uses). If they have not done the proper "baseline" procedure (because maybe they don't get audited much and who cares right?) then the results you get may be similar to what is in that table (from a Roche publication).

This underscores what I continue to harp about: INR is not a rock, its a bowl of jelly. Do not take measurements of it to be like using a micrometer to measure a piece of steel.

View attachment 887640

I harp about this because I consistently see people (OCD types) fussing about 0.1INR units and trying to skim the edges of their range. It is exactly because of this psychology that the later view of "Target" (not range) was introduced.

Now your Bio does not say if you have a mitral or an aortic (and I can't remember) so what I'd say is to go with your Coaguchek and if you're concerned about it go to a different lab (and ask them the question and a clear and direct way "I had a test somewhere else which gave me a different result to what I expected from another test on the same day, what reagent do you use in your INR testing"

Don't accept any fob offs or walk. That should get them to make sure that they baseline or you can at least compare to that chart.

Back to targets and jelly - I'd always advise staying in the middle of the INR Target as it currently is set by the Surgical Guidelines of your country (which are usually consistent internationally). Aim for the center of the target not the outside ring (which those trying to skim along at the bottom of their range do) and you will naturally account for any possible variances that exist and be in this all important range of outcomes

which according to what you've posted you actually are.

As to what I think you should do, I'd follow your Coaguchek and test again next week and see what that is ... follow up (with an @mention) if you get a result that is perhaps too high and maybe far away from what you want.

Best Wishes

Thank you so much Pellicle! I will read this over a few times.