Should I home test more than once a week?

[weissarthur]

I recently went to home testing for INR and I like to convenience. I use the CoaguChek XS system. My insurance pays for testing once a week, but I'm kind of a numbers guy. I'd like to test more often... maybe twice or three times a week... or basically when ever i feel like it. Perhaps I could uncover patterns in my eating behavior and pin down what really effects my INR and what doesn't. In short, I like biofeedback devices of all times (heart rate monitors, ekgs... even a standard scale that measures my weight) and find the information they give endlessly fascinating. I record the data in charts and try to determine cause and effect events that result in abnormalities.

My questions are:
1) is this a good idea for mesuring pt-inr? I teach Statistics at the university, so I understand how to interrupt normal variation in reads. But furthermore, I find the test soothing. However, Ive also benifited from the collective wisdom of this forum... Id really just like to poll people.... what do you think? Is my plan a good idea? or should I stay with once a week?
2) there is a chip that goes with each batch of strips. I'd have to take the chip out with each change in strips that I use. will that "confuse" the machine or cause it to have problems.
3) Are the strips expensive? Where do I get them? do I have to have a prescription to by these strips privately if the insurance wont pay for them?... is it a good idea?

Thank you in advance for you responses.

Art Weiss

 

[Agian]

I have the type of personality that would make me want to test more frequently. Why not? Eventually, you'll get enough confidence to reduce the frequency of the testing. BTW, I'm pre-op.

 

[weissarthur]

Im the same way with testing... i find it comforting... and i could adjust more to reads... Take care Again

 

[Protimenow]

I advocate for testing once a week, for a few reasons:

Research shows minimal risk of stroke in people whose INRs are below 2.0 (or lower) if the low INR is detected and corrected right away. For a person who is under (or un)anticoagulated for longer than a week, the risk of stroke increases. I don't think it's safe or particularly smart to go longer than one week between tests.

Back when it was a real hassle to get the INR testted -- drive to a doctor or lab, park, walk to the office from the car, wait to be called, get a blood draw, pay a lot for the test, etc., testing less often seemed to make some sense -- especially if the patient was believed to be consistently taking the same dose and hasn't changed dietary or other factors that could impact the INR. With the advent of meters that are convenient for home use (or use in doctor's offices), some of the reasoning against weekly testing (the ability to home test) have pretty much gone away.

A year or two ago, I was testing two or three meters, comparing the results to monthly blood draws. The meters were used weekly, or more often, and I determined that the meter that I trusted (and that reported INRs higher than what the hospital found after I had a TIA) was always reporting higher than actual. My preference was to have a meter that did NOT overestimate my INR -- I wanted to be confident that an INR of 2.0 on a meter meant that my INR ACTUALLY WAS higher than 2.0.

Last week, I had a blood draw. The Anticoagulation Clinic only calls me if my INR is out of range -- they didn't call me. For some crazy reason, they decided that my new range should be 2.0 - 3.0 (rather than 2.5-3.5). On the day when I had my blood drawn, my Coag-Sense meter told me that my INR was 1.8, and the CoaguChek XS gave me a 2.1. For that one day, I increased my warfarin dose by 50%. I probably should have tested one or two days later -- but I didn't.

I'm also a trained statistician, although I don't do much with that knowledge. It probably won't hurt to test more often than once a week, but don't drive yourself crazy by worrying about minor changes, or by making changes to your dosage. The INRs actually fluctuate, and it's usually hard to predict or understand the reasons for the changes.

If you can, also get your blood drawn once a month (or so) at a lab whose results you have some confidence in. (I had two blood draws on the same day a couple years ago -- one at a hospital lab and one at a clinic and the results were about .8 or so apart, if I recall correctly. Not all facilities can run accurate tests, and some facilities may not handle the blood properly, so inaccurate results may be not uncommon).

As far as the cost of the strips -- you can get them on eBay for around 5 or 6 dollars (or so) each. If you test more than once a week, you nay not necessarily be concerned with expiration dates.

As far as code chips are concerned, these are important. They calibrate the meter to the specific, tested, values of the reagent for which the strips are made. Consider it to be fine tuning between strips and machine. There should be little error injected into this system because Roche has a hell of a lot to lose if they send out bad strips. (Recent history confirms this).

One other thing -- the CoaguChek XS is a nice meter. In my experience, it's always given results that were higher than lab results. Research has shown that the higher the reported INR, the larger the variance between the reported INR and the lab result. At lower INRs, it's supposed to be very accurate. I personally prefer my Coag-Sense over my CoaguChek XS, but I use both, and usually compare one to the other, taking a rough average as the expected lab value. (This is one reason why a 1.8 on the Coag-Sense and 2.1 on the CoaguChek XS didn't really trouble me too much - my INR was probably around 2.0, but I still upped my dose one time, just to make sure that MY INR was at or above my desired minimum).

I'm interested in how you proceed from here.

 

[pellicle]

Hi

...but I'm kind of a numbers guy. I'd like to test more often... maybe twice or three times a week... or basically when ever i feel like it.

sounds reasonable. I believe that when you start is a good time to exactly test as often as you feel like. Further I like to record that so that I can then plot that for analysis.

I've done a whole month of every two days testing and another memeber here did a month of daily testing. His results were interesting.

Perhaps I could uncover patterns in my eating behavior and pin down what really effects my INR and what doesn't.

a laudible goal, but there are complicating factors. I have had several bouts of "Ahh I think I'm on to something here...." only to have it appear to not be the case over the next year or so.

I record the data in charts and try to determine cause and effect events that result in abnormalities.

I find spread sheets better, then you can chart as needed

My questions are:
1) is this a good idea for mesuring pt-inr?

more data is never bad

I teach Statistics at the university, so I understand how to interrupt normal variation in reads. But furthermore, I find the test soothing. However, Ive also benifited from the collective wisdom of this forum... Id really just like to poll people.... what do you think? Is my plan a good idea?or should I stay with once a week?

I think that its an excellent idea and if over time you decide differently then you'll have made that decision with the benefit of data.

I test weekly now, and on the basis of seeing a trend that results in a high or low reading do "ad hoc" testing for a few more days to determine where that trend does indeed go to (say, correcting to normal or not) to decide if I stay my hand on dose adjustments.

2) there is a chip that goes with each batch of strips. I'd have to take the chip out with each change in strips that I use. will that "confuse" the machine or cause it to have problems.

I don't understand the question ... the chip *must* be related to the strip batch. The machine will refuse to operate if you mismatch strip and chip. Strips come with a chip, the chip can only be used with those strips.

ou can remove the chip as often as you like (its a simple system, not a computer really) and test with different strips and their chip without any issue. Do you see yourself doing consecucitive tests with different batches?

3) Are the strips expensive? Where do I get them?

I buy mine online in Australia (I live in Australia) for about $138 for 24 strips. I see them simmilarly in the USA. I see eBay in the USA having them for good prices. Just demand that they are within date (or they can't be used by the machine) and that the packages are unopened.

You may find my blog posts here
http://cjeastwd.blogspot.com/2014/05...ocks-dose.html
and here
http://cjeastwd.blogspot.com/2014/09...ng-my-inr.html

interesting

 

[pellicle]

PS ... read this post by Ola
http://www.valvereplacement.org/for...onitoring/43179-novembinr?p=785192#post785192

 

[dick0236]

My questions are:
1) is this a good idea for mesuring pt-inr? I teach Statistics at the university, so I understand how to interrupt normal variation in reads. But furthermore, I find the test soothing. However, Ive also benifited from the collective wisdom of this forum... Id really just like to poll people.... what do you think? Is my plan a good idea? or should I stay with once a week?
2) there is a chip that goes with each batch of strips. I'd have to take the chip out with each change in strips that I use. will that "confuse" the machine or cause it to have problems.
3) Are the strips expensive? Where do I get them? do I have to have a prescription to by these strips privately if the insurance wont pay for them?... is it a good idea?

1. I doubt that testing more often than once/wk will normally add any meaningful info unless there has been a change in meds that interact with warfarin. I have tried this, a time or two, to see if diet changes affect INR and my results where inconclusive.

2. I do not know the relationship between the chip and strips but I do change the strip when I open a new strip container. That could be a problem if you get strips from two different sources......one for the insured program and one for the additional program

3. The least expensive expensive source would be Ebay, or similar site. Before I went back to the Coaguchek program, I used to get strips from Ebay at a cost of about $5-$6 each, and there will be no cost sharing with your insurer. If you go back to Coaguchek for the additional strips the cost will be double the Ebay cos.....if they will sell them to you without an Rx.

 

[tom in MO]

Your INR has a time constant of a couple of days. This means it takes time, about a week for a cjange in warfarin dose to bring an INR to a steady state.

Once a week is all you need to do if you want to maximize your "time in range". IIRC, Studies have shown that once a month will work too, when it comes to adverse events, but you will spend more time in range at a more frequent test rate. IMHO, every two week testing is now the "better" frequency. My clinic goes with every 3 weeks, until I am out of range, then they test every week.