Recommendations For Home INR Machine

[LondonAndy]

It might depend on what part of the universe the patient is in. If in the UK, or some (possibly all) parts of Europe you can buy directly from the manufacturer: CoaguChek INRange

update: Ah! just spotted the comment 12 messages back that you are in the US - apologies. But will leave this here in case useful for others.

 

[Protimenow]

No problem. Perhaps the information will be helpful to someone else.

Also - in the U.K. there's a newer model of meter that uses XS strips - the InRange. It has features that may be attractive to you. It's available on eBay, from the United States (apparently) and I'm sure you would be able to get it in the U.K. (Of course, a used meter bought on eBay may still be a good alternative).

 

[ScribeWithALancet]

I want to purchase a home INR tester. Anyone have any recommendations? Thanks.

I purchased a Coag-Sense from Wilburn Medical. It was pricey but the bundle included a one year supply of lancets, transfer tubes and test strips. Most important, since I have had it now for 3 months, I have 5 test data pairs from the Coag-Sense and from my HMO's lab. At the hi and low end the uncorrected Coag-Sense results are 0.4 higher then the lab. For the middle 3 test data pairs, they are 0.2 higher then the lab. There were two separate days about 6 weeks apart when my INR on the Coag-Sense came back with the same value. Both times the Laboratory blood draw came back with the identical values.

If you use the University of Utah approach to creating a regression equation with the data (Excel and Apple Numbers work fine), I can then predict the Lab results within 0.1 unit of INR from the Coag-Sense results except for INR values at the very bottom of my range where they are within 1.5 units. This is great for managing my INR between lab blood draws.

If you read the Coag-Sense FDA applications, you will find that they did a thorough job of documenting their validation and reagent use for the FDA. Based on my results, I recommend the Coag-Sense highly. Note that many on this forum find the CoagUChek to be very useful also. The Univ. of Utah papers I read to find the regression approach used both the Coag-Sense and the CoagUChek and found both to be highly predictive of the lab results from about 2 to about 5 with the regression equations. Like everything this approach has catches. The vendor of the meter (Coag-Sense and CoagUChek in this case) must not change reagent or approach. The Laboratory must not change test equipment or reagent. If a new batch of the same reagent comes in, they must revalidate the new batch to assure that it gives the correct numbers. Coag-Sense says that they always use the same reagent on the test strips but that they have to recalibrate whenever they get a new batch of the reagent in. (Did you ever wonder why you need to reenter the validation code when you get a new batch of test strips?, Now you know : - )

The vendor I purchased my Coag-Sense from said they could not sell me the CoagUChek because Roche has a policy of NOT selling to patients. i have read elsewhere on this site that the only way to get that meter in the USA is to purchase on eBay. Your Mileage May Vary.

Walk in His Peace,
Scribe With A Lancet

 

[Protimenow]

I'm rather surprised that your results with the Coag-Sense meter are higher than those from your lab. In my case, when I had a reputable lab, the results were slightly lower than the lab, or matched the lab. There was a period of time when I was using one lab and the prothrombin times for both were identical - but the lab's INR was different. I suspected that the reagents were about the same (resulting in identical prothrombin times), but the lab had different values for the reagent.

When I was also testing on the CoaguChek XS, I frequently found that the lab results were almost always equal to an average of the two meters.

To get FDA approval of a new device, the applicant has to demonstrate that results from the new meter matches that of the older meter. I'm not sure, but I see to recall that the original Coag-Sense meter had to match (within some degree of accuracy) the results of a CoaguChek XS. (But I could be wrong here).

In any case, I agree with your recommendation of the Coag-Sense meter.

Also - FWIW - I've been in contact with Coagusense - the company that makes the meter insists that they very carefully test the reagents in every batch of strips, to make sure that the results are accurate. You can see a barcode on the strips that provides detail about the reagent values (or something) on the strip. The new PT2 meter also has an NFC tag on the box that may possibly give the meter the same information.

The Roche CoaguChek XS strips also go through extensive testing - that's why strips come with a code chip. The chip provides information that contributes to an accurate test result. (With that said - I still think that the Coag-Sense is more accurage -- especially at higher INR values). In fact, the former CEO of Coagusense once told me that some hospitals use the Coag-Sense meter to validate any CoaguChek XS results that were above 4.0

 

[ATHENS1964]

In this site INR Self-Testing | Blood Clots
I read . << INR values obtained with the finger stick home testing devices typically correlate well and are able to be replicated with INR results that are determined from venous blood draws, making them reliable. In fact, recent research indicates that self-testing may produce better outcomes for patients who are eligible to participate.It is important to note that POC instruments are unreliable in about one-third of patients who take warfarin and who are also affected by the clotting disorder antiphospholipid antibody syndrome (APLS or APS). In these patients, the POC devices give INR readings that are too high, or the instruments can report an error message. If you have APS, your INR levels should be checked via a vein draw in a laboratory setting and compared with a POC reading from a finger stick. Only if both values correlate, may it be acceptable for APS patients to use a POC device. APS patients should discuss their testing options with their healthcare providers. >>

 

[Protimenow]

APL is a very rare genetic disorder that was first described in the 1980s.

Although meters might not give a reliable INR measurement for 1/3 of this small population, the above quote shouldn't be interpreted as indicating that most people who use meters to test their blood would get incorrect results.

 

[pellicle]

If you have APS, your INR levels should be checked via a vein draw

True

If... Do you?

It is important to note that POC instruments are unreliable in about one-third of patients who take warfarin and who are also affected by the clotting disorder antiphospholipid antibody syndrome (APLS or APS).

This does not say 1/3rd of warfarin patient's, so as approximately 5% of the population has APLS or APS, it means of that 1/3 or 1.667% of the population will have problems with PoC machines

 

[Protimenow]

Yes. 1/3 of the population of APLS or APS patients. I couldn't find the percentage of the population that have it. Thanks, Pellicle, for finding this.

 

[pellicle]

I couldn't find the percentage of the population that have it.

Actually I misread it, so its even less:
What is the prevalence of antiphospholipid syndrome (APS)?

One to 5% of healthy individuals have aPL antibodies. It is estimated that the incidence of APS is approximately 5 cases per 100,000 persons per year, and the prevalence is approximately 40-50 cases per 100, 000 persons.​

​

The Epidemiology of Antiphospholipid Syndrome: A Population-Based Study. - PubMed - NCBI

The estimated prevalence was 50 per 100,000 population. ​

 

[Protimenow]

Wow. That 1/3 statistic seems hardly worth mentioning. So - 1.67 per 100,000 people having APS may not have accurate test results with these meters - and even THIS has to be confirmed. Even 1/3 of the prevalence is barely worth mentioning -- UNLESS you HAVE APS AND take warfarin.

 

[Protimenow]

The Coag-Sense can test blood from a vein draw. If the blood is stored in a citrated tube (the common way for blood to be preserved for a PT/INR test) it may require some treatment to make it testable (but I'm not sure). If a drop of blood from the venous draw is put onto the strip once it's drawn, the meter will test the blood.

I'm not sure about the ability of the CoaguChek XS to test citrated blood samples, but I'm sure that, if a drop of blood that is taken from a vein and not put into a tube (if they can do this), it can also successfully test that drop.

And, FWIW, I've found that some labs grossly overstate INRs of drawn blood. It's good to have accurate labs that can be trusted to give correct results.

 

[Protimenow]

I've encountered what I'm considerng may be a crisis of confidence. Perhaps Scribe with a lancet can share his experiences here.

For more than a year, I've seen lab and hospital results more than a full point higher than those of my Coag-Sense PT1 and PT2 meters. I've used a few batches of Coag-Sense strips and trusted my meter over the lab results.

I just got some strips for teh CoaguChek XS (two packs of 6, expiring 5/31/2020) and used them for comparison to the Coag-Sense results. I expected the results to be a near match. The XS strips are not part of the recall. They were in a sealed package and the boxes didn't appear to have been tampered with.

My Coag-Sense gave me afalue of 3.1.

The XS gave a result of 3.9. I tested again, and got a 4.2. Although I realize that the XS can give a higher than accurate result, increasing in error as the INR increases, I'm concerned by the significant difference between the two meters. I'm considering that the labs (both from a large corporation and hospitals) may be closer to the CoaguChek XS, and their results may be within a 20% margin of error with the results of the XS.

I asked Coagusense about the difference between meter and hospital labs, and haven't heard from them for a week.

I just asked again. I'll see if they respond.

 

[ScribeWithALancet]

I've encountered what I'm considerng may be a crisis of confidence. Perhaps Scribe with a lancet can share his experiences here.

For more than a year, I've seen lab and hospital results more than a full point higher than those of my Coag-Sense PT1 and PT2 meters. I've used a few batches of Coag-Sense strips and trusted my meter over the lab results.

I just got some strips for the CoaguChek XS (two packs of 6, expiring 5/31/2020) and used them for comparison to the Coag-Sense results. I expected the results to be a near match. The XS strips are not part of the recall. They were in a sealed package and the boxes didn't appear to have been tampered with.

My Coag-Sense gave me a value of 3.1.

The XS gave a result of 3.9. I tested again, and got a 4.2. Although I realize that the XS can give a higher than accurate result, increasing in error as the INR increases, I'm concerned by the significant difference between the two meters. I'm considering that the labs (both from a large corporation and hospitals) may be closer to the CoaguChek XS, and their results may be within a 20% margin of error with the results of the XS.

I asked Coagusense about the difference between meter and hospital labs, and haven't heard from them for a week.

I just asked again. I'll see if they respond.

Your other posts today may have part of the answer hidden in them. About a year ago, I was told to take 8 hour Tylenol for pain as it was the only medicine that did not interact with Coumadin. I ended up in the Urgent Care facility of my health plan as my internist was 95% convinced I had a major bleed and a high INR but had seen Hematomas from blood clots and wished to make sure that it was a bleed so the corrective action would not be wrong. Right after seeing the Urgent Care doctor, getting an Ultrasound and a new INR, I was told to drop my Coumadin for a day and start a reduced dosage. Then, a different Coumadin Pharmacist called me and told me that the Coumadin Clinic had been wrong and that Tylenol can and will cause INR changes and I had to stay under 4 pills a day. I have subsequently found that my reaction to it varies and can sometimes be very strong and relatively short lived - 24 hours or less.

You mentioned that "yes, required dosing varies from individual to individual - it's often done by body weight - " We were told by a pharmacist that many medicines no longer carry corrections for dosages for age and body mass in their package inserts and so the doctors have stopped using those corrections. He also said that dose per ml of blood does vary by body mass and can and should have a real impact for most patients. 16 years ago, after my heart valve replacement, they used the then relatively new 8 hr tylenol to help wean me off of hydroxycodeine. The Tylenol did not affect my INR at all when I was younger. Nowadays, watch out. I am very glad that you and Pellicle recommended that I get my meter so that I can watch the reaction - and hopefully slip in an extra pill or two a day. Unfortunately, reactions to medicines do vary not only by individual but also by the age of that individual.
You mentioned in your other post that "... and, perhaps unknown to my cardiologist, another doctor prescribed an additional calcium channel blocker" This is why my health plan prefers that we get everything thru the same pharmacy chain and that the doctors make the order thru the same computer system. It forces BOTH the doctors and the pharmacists to look at all the medicines that are being prescribed and the computer system looks for conflicts.

Perhaps the glitches your doctors and their medical prescriptions are causing different kinds of glitches in the hospital lab results and the CoagUChek results then in the Coag-Sense results?

Since my Coag-Sense is giving me values consistently above the lab readings, I cannot comment directly on your readings. I found out that my health plans lab seems to have a 6 hour lag between when they draw the blood and when they result the INR. The ISI standard allows a drop of 10% in the INR for that time lag. If that is correct then my meter reading and the Lab reading would be always with 0.2 units and usually with 0.1 units. This differs from the regression analysis and correlation where only one reading was 0.2 units and the rest were within 0.1 unit.

This makes me confused about your high readings. Can you ask the hospital when was the last time they changed their reagent? Then ask them when was the last time they recalibrated their lab INR equipment and reagent against the ISI standard for INR measurement.

I have the advantage that I have only had the meter 9 months even though I have been on Coumadin 16 years. Thus, I have had the same lab, lab equipment, lab reagent, INR meter and meter reagent for that time. Even the same "lab" according to another poster, can send stuff out for processing elsewhere.

This whole business is trickier then I thought. I would like a way of better benchmarking the Coag-Sense but have found none better then your idea of having multiple meters and running them against each other. It now appears that to do that reliably, one must do it on a regular basis and I cannot currently afford that.

Walk in His Peace,
Scribe With A Stylus

 

[Protimenow]

Thanks, SWAL (or should I call you Scribe?), for responding to my post.

I wasn't aware of the new methods of figuring the correct dose - I still thought that body weight was the main factor used for dosing. I'll remind my doctors about my age (which they already have in their files, and that I seem to respond better to lower doses. Maybe this would help.

Regarding Tylenol (acetaminophen) - for me, it's a no brainer - it doesn't seem to work for me. Tylenol isn't the benign pain reliever that they want you to think it is. There have been warnings of liver damage in people woh take it chronically - and, I recall a warning that liver damage can occur after a few as ten consecutive days on the stuff. As you noted, it can also affect your INR.

I used to use one pharmacy - Costco - but I'm changing my pharmacy to one that delivers. I'm still working out balance issues secondary to my new medications, and until I feel that I can safely drive, I'll just get the stuff delivered. My insurance co-pays shouldn't change the cost of my medications - and for $5, not having to fight Costco is well worth it. (Costco pharmacy was really good about catching possible drug interactions - I'm hoping that the new pharmacy will be as careful). Also - FWIW - while I was in the hospital, all the medications that I'm now taking came from the hospital pharmacy -- I would think that they looked at possible interactions before sending them to the nursing station.

I hadn't heard about INR readings changing, based on the time it takes to process the blood. The hospital probably tested within minutes of the blood draw. The lab that I used collected the blood, transported it to a main lab about 100 miles South of me, and THEN tested the INR. You said that the longer the delay between blood draw and testing, the lower the INR results will be -- in all cases, these were still much higher than my meter's result.

As far as asking the lab about their reagents - I've done that, and was told that they're careful to test when they get a new reagent, etc., etc., and I'm sure that the hospital does this, too. I have no idea how extensive this testing and verification are.

I'm still troubled by the large difference in values between the CoaguChek XS and the Coag-Sense. I have no idea how the CoaguChek strips were stored before I bought them. I was able to buy short-dated (May 31 expiration) for about $1 each. The boxes were sealed and intact. There was no obvious damage to the boxes. The strips passed Quality Control, so they should have been okay.

It's been far too long to get a response from CoaguSense, so I'll try again.

I'm also going to call Roche to see if they can suggest anything. (They don't send strips out to mere mortals - you have to be on their service to get strips).

Years ago, after giving my InRatio complete faith, I had a TIA because a 2.6 from the meter was actually a 1.7 when I was in the hospital.

I tested many different meters, comparing one to the other, and decided on the Coag-Sense as the meter that I had the most confidence in. I also did a monthly blood draw to compare to the meters.

When I can afford to, I'll get more CoauChek XS strips. Like you, I can't really afford more strips after my supply for the next month or so runs out. I may wind up borrowing money to get more strips. Ultimately, if I can somehow afford to, I'll compare the two meters (at least the list is down to two - Coag-Sense and Roche meters that use the XS strips), so I won't have to run tests against a lot of meters and lab results.

I'm sure that, if I'm able to do a series of tests, and comparisons to labs, I'll share the results.