the 15 second rule

[Protimenow]

A few days ago, I proposed testing with two strips - one test taken within fifteen seconds of incision, the other taken much later.

I did just that:

First test - within fifteen seconds: 4.1
Second test - after a minute or more, not the first drop: 3.9

I used the same lot of strips, and the same meter.

From this single pair of tests, it appears that there is a small difference between first drop/within fifteen seconds, and later drop/a minute or so after incising.

In my case, assuming that my InRatio2 is .5 or so above lab test, both are close enough to my range that I made no change -- but the difference, in this one test, was real (though probably not significant).

I will be comparing Protime with Hemochron in a couple days -- both meters are made by the same company. My tests will be within a few hours of each other. The lab's hemochron will have been calibrated (or at least tested for QC), and it would be interesting if there's much difference between the two. If I feel like I have enough fingertips, I may even do a test using the InRatio 2 to see how it compares.

 

[Bina]

The original question here was the 15 second time limit on the Coaguchek XS monitor. YES, the instructions need to be followed precisely or the monitor will give you an error message.
My best advice is to do your test in an organized manner.

Lay out your test kit on a table. Wash your hands in warm water, rinse well, dry well.
Then while the monitor is doing it's self check with the strip inserted, you have time to hang your hand down and make sure it is warm and has blood supply.
When the monitor asks for that blood drop, you will have no problem with the 15 second time limit.

I won't re-type the rest of the test, but I've been doing it for 5 1/2 years with TOTAL success.

 

[pellicle]

.
When the monitor asks for that blood drop, you will have no problem with the 15 second time limit.

Except of course that I do...

My solution ATM is to swing my arm around like kids do sometimes during the 30sec warm up. This seems to get the blood flowing down to my finger tips and I get my blood. Just

I have tried deeper settings and multiple stabs, to no avail.

Perhaps it actually is that we are all that wee bit different and what works for one is not a guarantee of total success for another.

 

[pellicle]

A few days ago, I proposed testing with two strips - one test taken within fifteen seconds of incision, the other taken much later.
...
First test - within fifteen seconds: 4.1
Second test - after a minute or more, not the first drop: 3.9

I used the same lot of strips, and the same meter.
s.

Nice test. Suggests that there is a difference.

My last two tests were very close to the values from veinus samples.

 

[Protimenow]

If I had an XS, I would have done the tests with an XS. My point in posting the results with an InRatio 2 is that, like the XS, the meter is designed to use the first drop, collected within fifteen seconds of incision. This suggests that both tests are designed to use the effects of the clotting factors that are close to the skin when you incise it, rather than testing on the blood that is deeper inside (capillary blood, probably mixed with plasma, but using a somewhat different test method than the XS or the InRatio). The difference in the two results - though not earthshaking - suggests that there is probably a good reason that these meters want the first drop - and they probably want it before clotting starts (or before it's gotten to a certain point after which the test results may be skewed).

FWIW -- Two days ago I had my blood tested at an anticoagulation clinic at a hospital. They use the Hemochron Signature Elite -- a meter that is also used in operating rooms to test INR and other blood factors during surgery. This is a professional meter (I have an earlier model but can't use it because I don't have the quality control devices) that requires QC testing every day that it is used. Later that day, I tested with my ProTime meter and the 5 channel strips. The test takes more blood, and more time, but may be more accurate than the other meters. The results on the Hemochron and the ProTime were the same -- and the Prothrombin time was .3 seconds different from my ProTime and the Hemochron meters. For speed, ease of use, and the fact that getting blood is less of a hassle with the InRatio than it is with the ProTime, my meter of choice is the InRatio, although I'm resigned to the fact that the InRatio results may always be .2-.5 or so higher than the lab results. (So - with a range of 2.5-3.5, I'm okay with an InRatio value of 2.9-3.9 or so).

(No -- as I stated in an earlier post, I don't work for ITC (which manufactures the ProTime meters and supplies), and I don't sell or promote their meters. Other than a bad set of 3 channel cuvettes I got earlier this year, I've found that the results on this meter seemed to be closer to lab results. The ProTime meter does NOT use the first drop of blood)

 

[JiFaire]

I just received my Coaguchek XS - the one recommended by the nice professionals at my anti-coagulation clinic. Tomorrow, I will train on it with my pharmacist, who was formerly a cardiac unit pharmacist and has worked with anti coagulation before.

Honestly, I'm sorry you have had such a tough time with the professionals who have been assisting you, and that your attitude has become coloured by that experience. The people I've been working with have been exceptional; they listen well, do not discount anything I've brought forth (ie: I suggested a reduction in my simvastatin regimen based on a study I had from NIH; they downloaded the study, validated the ideas with my cardiologist, and reduced my dosage accordingly.)

The professionals at the University of Alberta anti coagulation clinic are top-notch.

About the 15-second rule: I asked my pharmacist, and he indicated that surface capillary clotting is a cascade reaction that begins upon incision, and the meter/strips are calibrated to accurately determine INR within that window. As time progresses past the 15-second window, the cascade progresses, and so the INR will read lower and lower (as the blood begins to clot, it begins to get closer to 'untreated' blood, and so the ratio approaches 1.0.

Made sense to me, with my outdated human physiology degree. Most days, I know enough to understand the big words, but every little bit helps.

 

[pellicle]

If I had an XS, I would have done the tests with an XS. My point in posting the results with an InRatio 2 is that, like the XS, the meter is designed to use the first drop, collected within fifteen seconds of incision.

I am uncertain if your post is directed at me as you made no reference to whom it was addressing.

Based on this assumption it was me (and discount this if this is wrong) I do grasp the point that you don't have an XS and did your tests on the equipment you have.

my point in replying was (as I quoted your points) that the tests were quite close together and the results were withing what I consider to be reasonable experimental tolerance. As has been mentioned these things are not identifiable to with two decimal places ...

This suggests that both tests are designed to use the effects of the clotting factors that are close The difference in the two results - though not earthshaking - suggests that there is probably a good reason that these meters want the first drop - and they probably want it before clotting starts (or before it's gotten to a certain point after which the test results may be skewed).

I agree ... and thought that was clear in my post ... if you were not replying to me then discount what I have said.

 

[Protimenow]

My reply was not directed at anyone in particular. I was only stating that my test was on an InRatio, and not an XS, but that I thought the 'first drop within 15 seconds' requirement meant that the two meters relied on the same basic process for INR testing. That's all.

Roche claims that their results are very close to lab results. In my experience with the InRatio, this is not always the case--but if it's possible to predict a 'reliable' difference, then the test is every bit as good as XS or lab (or ProTime) for determining that I'm in range. (Being in range is the most important aspect of INR testing, and having a method (or two) to confirm when I AM in range, and to let me know when I'm not, is very important. If there was a meter that was 5 points high -- reporting that my blood was between 7.5 and 8.5, as long as it was ALWAYS 5 points high, I'd still be happy to use that meter. As long as there is a 'reliable' variance that I can adjust for, the results should be fine. It's somewhat surprising, though, that meter manufacturers who determine that the results are consistently high don't have a correction programmed in to their meters).

 

[pellicle]

more current test results from my home coagucheck testing VS veinus sampling
date - Coagucheck - Lab veinus
14/12/2012 - 3.2 - 3.4 (note I think I went into nearly 25 seconds to get my drop of blood)
17/12/2012 - 2.7 - 2.8
21/12/2012 - 2.8 - 2.8
28/12/2012 - 2.5 - 2.6

I post these for anyone wondering about home testing and how 'accurate' it may be.

As an example, anyone wondering about the 'accuracy' difference of 0.1 here, I would suggest that rounding issues could make it seem more than it is. If the Lab came up with 2.57 and my coaguchek came up with 2.53 it could be that one would round up to 2.6 and the other round down to 2.5

I personally am not at all disturbed by 0.1 difference

 

[Protimenow]

The .1 difference shouldn't be troubling at all. That's an excellent correlation between meter and lab. (In the past, I've seen labs that don't correlate with each other, even though the blood is drawn within hours of the other lab blood draw). Roche claims a very high correlation with lab results - and your reported results support this claim.

(In my experience, my InRatio and InRatio 2 don't usually come as close - but they always seem to be somewhat higher than labs. I've gotten to where I assume that the InRatio will always report between .3 and .6 (or so) higher than the labs, so I adjust my target range, as reported by the InRatio, to accommodate for this).

(Also, in my experience, when I don't include a lot of bad 3 channel ProTime strips (which I reported to the manufacturers), my ProTime meter also correlates very well with the labs).

 

[JiFaire]

I personally am not at all disturbed by 0.1 difference

Nice numbers, Pellicle!

 

[Noyolk]

I have been testing my coaguchek XS against the hemochron signature elite that the clinic uses. My meter is new(11/13/12) and I received the in home training from Alere when it was delivered. All tests were run with the technician performing the finger stick then wiping away the first blood, then forming a drop for the sample. Within 1 min of their test, I did my own finger stick, did not wipe and deposited on the coaguchek. The 12/31 date was the only change with me using 3rd drop of blood from technicians stick. I think i will figure my home testing is .5 higher than actual from now on.

date XS Hemochron
11/26 2.5 2.0
12/11 2.7 2.3
12/18 3.2 2.5
12/24 3.0 2.3
12/31 3.6 3.2

 

[TheGymGuy]

more current test results from my home coagucheck testing VS veinus sampling
date - Coagucheck - Lab veinus
14/12/2012 - 3.2 - 3.4 (note I think I went into nearly 25 seconds to get my drop of blood)
17/12/2012 - 2.7 - 2.8
21/12/2012 - 2.8 - 2.8
28/12/2012 - 2.5 - 2.6

I post these for anyone wondering about home testing and how 'accurate' it may be.

As an example, anyone wondering about the 'accuracy' difference of 0.1 here, I would suggest that rounding issues could make it seem more than it is. If the Lab came up with 2.57 and my coaguchek came up with 2.53 it could be that one would round up to 2.6 and the other round down to 2.5

I personally am not at all disturbed by 0.1 difference

Wanted to contribute that Coagucheck seems pretty accurate over here as well.
I had a venous lab draw as well and used CoaguCheck XS within 1 minute to draw blood from my finger as well. The difference was .2, with lab INR being 2.4 and coagucheck showing 2.2.

 

[pellicle]

I. All tests were run with the technician performing the finger stick then wiping away the first blood, then forming a drop for the sample. Within 1 min of their test, I did my own finger stick, did not wipe and deposited on the coaguchek

Gosh, to me those results are not sufficiently in agreement. I would not be satisfied with a variance of 0.5 or more.

If I may ask was your blood drop on the XS formed and delivered to the meter within the 15 sec?

 

[pellicle]

date XS Hemochron
11/26 2.5 2.0
12/11 2.7 2.3
12/18 3.2 2.5
12/24 3.0 2.3
12/31 3.6 3.2

quickly graphed

my "theraputic range" is between 2.2 and 3, so with a greatest variance of 0.7 in your figures if I was using such I could be outside it by a margin. Particularly of interest is the 0.5 variance when at 2.0 which if I was using such results I could be thinking that I am at 2.3 when I am at 1.8

I would be interested to know if you're following the 15 sec rule on the application of blood to the XS or "milking" the finger (or both) as these will contribute to the XS giving higher readings than actual (as I understood that some clotting will have begun before the test begins).

 

[Noyolk]

I have no problem in the sample being placed long before the 15 seconds. I also do not have to milk my finger any more than 1 squeeze near the site.

I am also not excited about the variance. My repeated weekly testing is over for now as 2013 starts out my ins. coverage at substantially more out of pocket.

 

[Protimenow]

I would also be somewhat concerned with a .5 variance. I've made comparisons between my InRatio and my ProTime meters -- the ProTime is made by the manufacturers of the Hemochron, and asks you to wipe away the first drop. When I made my comparisons, I used the lancing device that came with my ProTime cuvettes (otherwise referred to as strips), put the first drop of blood on the InRatio strip, wiped away any excess blood from my finger, then filled the collection cup on the ProTime lancing device. (This sounds somewhat similar to what you were doing at your lab). In my last pair of tests - testing on a ProTime with a five channel cuvette and a Hemochron, within a few hours of each other, the tests were practically identical. (I do know, however, that although the Hemochron is touted to have lab accuracy, it requires some quality control testing each day that it is in use, and the meter may also occasionally undergo recalibration. I'm thinking that it may be possible that the Hemochron wasn't completely accurate (though I can't imagine them NOT doing regular quality control tests). Still - all that being said, I'd be somewhat concerned about the high degree of variance - .5 IS a lot - between Hemochron and Coaguchek XS. If I had the same result, and a narrow range of 2.2-3.0, I'd aim for CoaguChek XS values between 2.7 and 3.4 or so, just to be comfortable that my INR puts me on the safe side).

You commented on out of pocket -- if you trust your meter to be reliable (and reliable can mean ALWAYS .4-.7 above the Hemochron), you should be able to do weekly self-testing and avoid the cost of a visit to a clinic. Being able to self-test, with occasional visits to a clinic, should be fairly comfortable on your wallet.

 

[pellicle]

I am also not excited about the variance. My repeated weekly testing is over for now as 2013 starts out my ins. coverage at substantially more out of pocket.

Well as long as you are comfortable... I wouldn't be

I am not sure what you mean by the repeated weekly testing being over, as testing remains ongoing I thought

 

[Noyolk]

Sorry, I was referring to the testing of the XS vs. the Hemochron in the clinic. I will continue weekly home tests.

Weeks ago, Alere called to follow up on the in home training experience, and I gave them the difference in the first two tests. They immediately passed me up the phone tree to a supervisor who left me with her direct #. Now I am going to call and find out what they can do with the remaining data. Will keep you posted if it worth anything.

 

[Protimenow]

My experience with Alere -- at least as far as the InRatio goes - is 'trust the lab.' You may be told the same thing.

The real fly in the ointment may be that, in this case, the 'lab' is a Hemochron meter. Although the Hemochrons are supposedly lab equivalent (perhaps even better than labs because they bypass the possible mishandling of blood between the time of the blood draw and the time that the lab finally gets it, and because of some question about the equivalency of the reagents used at the labs), Alere may call into question whether the Hemochron results can be trusted. (There's also a bit of a subtext here, too -- ITC, which manufactures the Hemochron also makes the ProTime meters -- if they question the accuracy of the Hemochron, could they also, by extension, be calling into question the accuracy of a competing meter?).

The Alere supervisor will undoubtedly run you through a series of questions that are part of their 'questionable results' protocol --- are you using the first drop? How long does it take to get the first drop on the strip, etc., etc., etc. Once you assure them that you are running the test correctly, they'll possibly escalate the issue (and may even swap your meter or send you a new set of strips).

It'll be interesting to see what they will do.

(And, yes, as far as I am concerned weekly testing is the appropriate interval -- even if your results are stable from test to test to test)