home-lab difference

[Soilman]

Howdy folks,

My cardio has no experience with allowing his patients to use home monitoring machines and has always had them have blood drawn at the hospital lab. I convinced him to allow me to get a home monitor (coaguchek xs). He is dubious of the machines accuracy and insisted on compairing it to the hospital lab. Well, I used the coaguchek for the first time this morning after having blood drawn at the hospital as well. The coaguchek result was an INR of 3.8. The lab came in at 3.2. That is a significant difference for my cardiologist. He's going to rely on the hospital lab reading against my meter every time. Unless I can establish a consistent parellel over the next few month between the lab and my monitor, I may have purchased a very expensive piece of equipment for nothing. Any suggestions?

By the way, I contacted Roche and they said the 3.2 vs. 3.8 compairson was within their guidelines...but convincing my cardio of that is another story!

 

[Karlynn]

Unfortunately your cardio is not up to date (or speed) on INR monitoring. I don't have the time to look for them right now (maybe their in our References forum) but there are articles published about studies that show that those who home monitor AND self-dose/manage have much more stable INR's

What your cardio doesn't understand is that the lab could have had that same difference if they ran 2 back to back tests from the same tube of blood. He is of the misconception that the lab INR is tantamount to the 10 Commandments on the original stone tablets - and it's not. You have no way of knowing how long your blood sample sat around before testing - you don't know if there was any operator error.

Many cardiologists use the same machines in their office that we use in our homes. My cardio has used a machine since well before I started home testing. Now we both use the INRatio.

And Rouche is right - the differences you got are acceptable - because the lab could have also had those same differences with 2 back to back tests. Unfortunately it looks like it's going to be up to you to educate your cardio. I've had one lab test run intentionally since I've been home testing because of a questionable home machine number. And you can see by my signature how long I've been home testing.

GOOD LUCK!

 

[Bina]

Don't let your cardio's inexperience affect you.

If you are going to parallel test, you would need to bring your home monitor to the lab and test at exactly the same time as the vein draw, making sure that the vein sample also gets checked right away....nearly impossible.

I trust my monitor is always within a .2 difference, and my INR is very stable.
You have bought a very sophisticated, quality made home tester, enjoy it.

 

[Ross]

Also different reagents will give different results. Karlynn pretty much summed it up. The Cardio needs to get with the program and educate himself on growing trends.

I'll try to find you a sheet of results from lab and machine tests to show they are all in the same area. No two tests, back to back or even at that same time will yield the same results.


http://archinte.ama-assn.org/cgi/co...ffda7be0f79534c578c500c7&keytype2=tf_ipsecsha

http://www.theannals.com/cgi/content/abstract/36/5/769

This one is from Hemosense, but all the others I've seen are pretty much the same:
http://www.hemosense.com/docs/5500209_INRatio_vs_MLA_WhitePaperRevC.pdf

http://www.hemosense.com/docs/5500285_INRatio_vs_LAB_POC_RevB.pdf

 

[netmiff]

oh ! good grief

oh ! good grief

I was about to post exactly the same question !!! I have been home testing for just a very short while now, and have been in 3.4 or so. Last time, I did a parallel comparison test at the lab, and it came back 3.6; my test, which I did as soon as I got home, was 4.2. Doctor took the 3.6 as gospel .... and I know that the lab does not test on the spot, but sends them to a central lab on the other side of town.

So, who do I believe?

BTW, I have Coaguchec XS.

 

[Ross]

Let me see if I still have my chart that may help you understand more. INRatio has an ISI of 1. Most labs use reagents with an ISI of 2 or more. I don't know about the Coaguchek xs, but the earlier models used an ISI of 2.

 

[jeff]

I was about to post exactly the same question !!! I have been home testing for just a very short while now, and have been in 3.4 or so. Last time, I did a parallel comparison test at the lab, and it came back 3.6; my test, which I did as soon as I got home, was 4.2. Doctor took the 3.6 as gospel .... and I know that the lab does not test on the spot, but sends them to a central lab on the other side of town.

So, who do I believe?

BTW, I have Coaguchec XS.[/QUOTE


I'm having the same problem with my coaguchec XS.i have bin testing at the lab and self testing since the start of December and only twice is the reading the same as the lab .the biggest difference being.the lab was 4.2 and the XS got it to 5.3.then the next day i checked it again and XS gave me a reading of 5.1
so which one is the correct reading .my doctor stood by the lab result .any info is appreciated .
cheers Jeff. Ps i for got to say hello to very one as this is my first post on the site

 

[Blanche]

Ross:
I am confused.

The International Normalized Ratio (INR) was developed by the World Health Organization to account for the fact that different ISIs (International Sensitivity Index) produce different PTs (Prothrombin Times represented in seconds). Therefore, an ISI of any value (1.0, 1.6, 2.0, or 2.4 as in the example provided) still produces the same INR=1.0. The INR is merely a mathematical ratio. I don't see how that would account for the differences mentioned here.

The following article describes this process.

http://www.enw.org/Research-INR.htm

I think the most important sentence is, "It (INR) is simply a calculation that corrects for the variability of the PT results attributable to the variable sensitivities (ISIs) of the thromboplastin of the agents use in the labs."

I think that a possible explanation might include the variability of a person's PT which can fluctuate all the time.

I do believe that Dr. Allen wrote of this somewhere. I will look for it.

Blanche

P.S. I remember when Albert tested at the hospital, then at home on two monitors. The results of all three tests differed. We tested on the two machines at home again that day, and both were different and had changed from earlier in the day.

Regards,
Blanche

 

[lance]

Target range of your INR

Target range of your INR

Soilman,
If you have a mitral valve the range is 2.5 to 3.5. Neither of the test results would indicate a dose adjustment. So what is your doctor's problem? I understand his concern over a method he is not familiar with. It looks like you will have to educate him.

How often do you test?

 

[jeff]

Howdy folks,

My cardio has no experience with allowing his patients to use home monitoring machines and has always had them have blood drawn at the hospital lab. I convinced him to allow me to get a home monitor (coaguchek xs). He is dubious of the machines accuracy and insisted on compairing it to the hospital lab. Well, I used the coaguchek for the first time this morning after having blood drawn at the hospital as well. The coaguchek result was an INR of 3.8. The lab came in at 3.2. That is a significant difference for my cardiologist. He's going to rely on the hospital lab reading against my meter every time. Unless I can establish a consistent parellel over the next few month between the lab and my monitor, I may have purchased a very expensive piece of equipment for nothing. Any suggestions?

By the way, I contacted Roche and they said the 3.2 vs. 3.8 compairson was within their guidelines...but convincing my cardio of that is another story!

i also contaceted roche and was told that the tolerence range for the xs was 0.5 to 1.o1.which is a wide range.not surprising my doctor thinks its unreliable .

 

[Ross]

i also contaceted roche and was told that the tolerence range for the xs was 0.5 to 1.o1.which is a wide range.not surprising my doctor thinks its unreliable .

Ask him how that makes it unreliable. Is he going to make a dose change with that close of a tolerance? If so, get a new Doctor. Also, find out what the labs reagent ISI is and what your xs is. I think the xs is 1.0 but I'm not sure. Reagents make all the difference in the world.

 

[jeff]

Ask him how that makes it unreliable. Is he going to make a dose change with that close of a tolerance? If so, get a new Doctor. Also, find out what the labs reagent ISI is and what your XS is. I think the XS is 1.0 but I'm not sure. Reagents make all the difference in the world.

i thought 0.5-1.01 was a big difference .if the lab say my INR is 4.0 my xs say's 5.01.personaly i think that is to much of a difrence to dose correctly.
may im missing the point here if so please explain it to me

jeff

 

[Ross]

Jeff it's entirely possible to test back to back and have up to .6 of a variation. Your only talking .5 difference. With INRatio, .6 is allowable. Whomever at Roche had to have given you wrong information because if there were that much of a spread, the FDA wouldn't have certified it. If the FDA trusts it, shouldn't your Doctor?

 

[Soilman]

Mine is the aortic valve and I have the On-X. In the beginning, the doc was keeping my INR about 2.0-2.5. We had a hard time stabilizing it. (it kept dropping). I guess, for my situation, 3.8 would be a bit on the high side. The doc's office even said that reading would warrant a doseage change. I agree that the lab reading are likely just as variable as my machine, but since I'm his only patient (the ONLY patient in two counties likely) who has and uses a home monitor, it's going to be very unlikely I'll be able to "educate" him. The doc said to test again (at lab) in a month. I haven't decided if I'll home check in between, because my numbers won't mean diddley to the doc because of the difference. If nothing else, my job is suppose to move me in about a year. Then I'll get a cardio who WILL go by the monitor. Still, I'm dissapointed in the difference, because a friend and fellow forumite from Canada has the same monitor and is always within a point or two of the lab.

 

[Ross]

Bury these guys in white papers of their authoritive peers. They cannot deny studies conducted by their peers. Look up Dr. Jack Ansell and you'll find more then enough ammunition to pin your Doc to the floor.

http://www.ismaap.org/508.0.html
http://www.inrmagazine.com/aboutINR.php
http://www.ima.org.il/imaj/ar02nova-15.pdf

http://www.anticoagulation-and-more.org/sweden/sweden_erkrank_throm1.htm
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[evelyn2]

Hello everyone,

Haven't been around for awhile - hope everyone is doing well.

I just got insurance approval for a Coag Check XS. I will be receiving it on Saturday along with training from a QAS nurse. I am so excited to start home testing.

I will be the only patient from the coumadin clinic doing home testing. Still haven't worked out with the nurse practioner how they will follow me, which was one of the requirements from my cardio because she did not want to have anything to do with checking my coumadin.

Recently I had a reading of 2.8 and 2 weeks later I was 2.0. The clinic kept me at the same dose and my next appt. was to be one month away. I felt I was trending down and decided to up my dose 2.5 mg once a week. At that one month appt. my INR was 3.
I have the algorithm chart from Al Lodwick and feel like I should be able to adjust my coumadin dose.

This thread on the different readings is interesting. At the coumadin clinic, if they get a reading of 4 or above, I have to have a lab draw. Usually the lab value is slightly higher. They then dose me based on the lab draw.

Do you think it is safe to adjust your dose if your machine reads 4 or higher.

Evelyn

 

[Ross]

Do you think it is safe to adjust your dose if your machine reads 4 or higher.

Evelyn

Certainly. Anything higher then 4 and it's time to start skipping some dosing depending on how your body reacts to the medicine.

If your not used to it yet, which if doing what you did got you the INR 3 result, you've got the idea. If ever uncertain, ask. Don't do anything super silly without letting someone know and even then, I don't recommend it.

 

[catwoman]

I will be the only patient from the coumadin clinic doing home testing. Still haven't worked out with the nurse practioner how they will follow me, which was one of the requirements from my cardio because she did not want to have anything to do with checking my coumadin.

Recently I had a reading of 2.8 and 2 weeks later I was 2.0. The clinic kept me at the same dose and my next appt. was to be one month away. I felt I was trending down and decided to up my dose 2.5 mg once a week. At that one month appt. my INR was 3.
I have the algorithm chart from Al Lodwick and feel like I should be able to adjust my coumadin dose.

This thread on the different readings is interesting. At the coumadin clinic, if they get a reading of 4 or above, I have to have a lab draw. Usually the lab value is slightly higher. They then dose me based on the lab draw.

Do you think it is safe to adjust your dose if your machine reads 4 or higher.

Evelyn

Evelyn:
From your profile, I see that you're a registered nurse. You should be able to handle all of this -- without being bird-dogged by your NP or cardio. Sounds like you pretty much have the hang of this already, before you get your "toy."

 

[lance]

Hello fellow Ontarion

Hello fellow Ontarion

I was about to post exactly the same question !!! I have been home testing for just a very short while now, and have been in 3.4 or so. Last time, I did a parallel comparison test at the lab, and it came back 3.6; my test, which I did as soon as I got home, was 4.2. Doctor took the 3.6 as gospel .... and I know that the lab does not test on the spot, but sends them to a central lab on the other side of town.

So, who do I believe?

BTW, I have Coaguchec XS.

When I wanted to home test several years ago, my PCP wouldn't hear of it. Toronto General Hospital taught me to use my original "S", I take the test and e-mail the results to them and they manage my dosing. Could you do the same with Hamilton General? Maybe they have knowledge of home monitoring by now. Just a thought. It doesn't seem your doctor isvery confident in the method.
Just a thought.

 

[Ross]

What disturbs me is that they've been doing this home testing stuff for years in other countries, then the Doctors here act like it's something new. There isn't a one of them that can convince me that they don't know about it. If they don't, they haven't been reading nor learning anything and it's time to find a new, up to speed Doc.