Okay, so my Dad has a blood clot in his leg. He did the Lovomax (?) injections and is taking the warfarin pills, doing the delicate dance between clotting and bleeding out. He’s going to the hospital every 3 days for a blood draw and adjusting the meds accordingly.
Is there a “home meter” similar to the diabetes meter, that he could use to get these readings at home, and then call them into the doctor? My SIL, who had a heart attack in July, goes to a Coumadin clinic associated with her hospital. They do a finger prick test there to get her readings. Dad’s hospital doesn’t offer this “clinic” approach, but it seems to me that with all those clotting issues out there, it would be possible to do a home test and eliminate the driving to and from (which can be kinda dicey here in Chicago snowstorm season).
What do people with no practical access to hospital care do in these situations? There’s got to be a better way, right?
There are home PT/INR tests out there, but I’ve never used any of them. I don’t know how expensive or accurate they are.
Typically when I have a patient who can’t get into the clinic I have one of the local home health organizations go out and check it. Depending on the HH service and the payer, though, it can be difficult to arrange; usually if there’s any possible way for someone to bring the patient in, even if it’s ridiculously impractical, they don’t want to pay for HH.
Our daughter is on Coumadin for life. We’ve priced the home INR meters at about $1200-$1400 for the machine (this was for the most reasonably priced ones) and gods know how much for the strips. Since we have yet to save the money for the machine, we haven’t even looked yet. Luckily, until then there is a good anticoagulation clinic very close to our home.
IIRC, the big barrier to home testing is the difficulty in performing an accurate, reliable test day after day. Home monitors would be great, if they can be counted on to give useful info. But if it reports an INR of 1.9 when it’s really 1.1 or 4.4 or 15, then there will be trouble.
That’s why home units are so pricey. Accuracy costs a lot, at least at this time.
Clinical laboratories are required to recheck and recalibrate their INR results against standards regularly, and I believe many labs do so daily.
At least that’s my understanding of the current status of the issue.
They’re required to check once a day at a minimum, and more typically at the beginning of a shift making that 3 times a day. The same goes for chemistry and hematology testing as well. I have not heard much about the portable INR machines, and I would assume that they are about as accurate as the glucometers; they’re not tricorders. Knowing one’s CYP 2C9 and VKORC1 phenotype can go a long way toward stable anticoagulation for those who are slow metabolizers.
Do they check the machines against each other? The small one in the clinic I go to is about .3 above the results from the lab, and I had to postpone a cardioversion once because of it. I only go once a month now, so I’m not interested in the home version, but it is good to know the cost.
Can you please explain this in terms a layperson can understand? My dad is having a helluva time getting to the 2.0 - 3.0 point the doctor wants him at. He had a draw today, and after 2 weeks, he’s at 1.61 and they upped his dosage to 10 mg per day for 2 days, and then 7.5 til Friday (his next draw). He was doing fine during the Lovomax period. Now it’s all fucked up. I’m a little nervous that this clot is just getting worse.
No, they don’t, and this has been one of the most vexing things regarding coag testing. It’s also the reason for introducing the INR: the calculation takes into account variations introduced by reagents, instruments and methods of measurement. Theoretically, your INR should be the same when measured on several different machines. Still, I used to get irate MDs on the phone asking me why my machines were so poorly maintained; their patient had measured X two days before in their office (and POLs were notorious for poor quality management and staff training 10 years ago), and now I’m reporting out something different. A patient’s vitamin K intake can dramatically alter the readings in a relatively short period of time. Put that together with a poorly-functioning VKORC1 enzyme and it takes a lot of frustrating time to properly titer the patient on warfarin.
When any clinical machine is tested for accuracy, it is done so using quality control material first. If there is more than one machine then bias testing is performed, often with a patient sample. However, the results of the quality control material trumps all. This is also an issue with the portable glucometers or INR instruments. It is easy to not check, check improperly or mis-interpret the results. Med Techs can also perform mean, standard deviation and CV% calculations in our sleep, as that is the only way we can measure the machines accuracy and precision.
Sorry, I didn’t see your post while I was posting. CYP 2C9 is a gene that makes an enzyme that breaks down coumadin. There are a number of known point mutations (changes in a single DNA base) that significantly slows the speed at which the enzyme breaks down coumadin. This is an issue in about 15% of the US population, and varies by race. VKORC1 is an enzyme involved in vitamin K production. If VKORC1 is slow due to point mutations, then vitamin K stays around a lot longer to participate in making clotting proteins. So a healthy meal including broccoli can counteract the anti-coagulation action of coumadin. Someone with a poorly functioning VKORC1 enzyme make take days to clear such a vitamin K dose. CYP 2C9 and VKORC1 are known as pharmacogenetic tests.
Yeah, I received a sheet of High, Medium, and Low vitamin K foods. Because my dad has been pretty confused lately, I told him to stay away from all green stuff and told him to skip his multivitamin until we get a better handle on it. He has called me to ask about different foods that he wants to eat, so I’m pretty sure he’s following the dietary restrictions. He was positively thrilled to learn that ice cream was a “go.”
The information about the enzyme is interesting. Is that something they normally check prior to starting the coumadin therapy?
Pharmacogenetics is still a new concept, and it is slowly being adopted by physicians. Pharmacogenetic testing for certain genes is not routine, though. I hold hope as 2C9 (along with several other genes) also metabolizes a lot of other drugs, so the test results can inform the patient of many, many other drugs they may be given in the future. I’m not as sure, but I think some insurance companies have agreed to pay for it (it’s a one-time cost, as your genetic profile doesn’t change) while others don’t consider it to be necessary for diagnosis and treatment. Medical schools are starting to teach it, so the youngest MDs out there are starting to consider it part of their diagnostic palette. Some of the older MDs are also starting to come on board as well.
