frequency of testing?

[ski girl]

Just wondering . . . how frequently does everyone test their INR, and are you managing your warfarin yourself or is that done by a clinic or doctor?

I'm not sure how I got through the cracks in the system, but no-one ever told me how often to test or gave me guidelines on managing my dosage. When I do self-test (once every 2-3 months) I'm within range so I've just quit worrying about it. :redface2:

 

[pellicle]

Personally I self test weekly

Coaguchek XS

Probably its in needed and fortnightly would be sufficient perhaps less. Given its $5 a test and takes me 5 min at home I don't mind the overhead.

When I was being monitored and dosed by QML (Queensland Medical Laboratories) they never seemed to want to go more than fortnightly.

If youre always in range its probably not worth stressing over.

 

[ski girl]

Heheh well I'm definitely not stressing over it . . .

I was only out of range once and that was after a week of washing the meds down with a BIG glass of grapefruit juice! Then I was 9.0. No more grapefruit juice for me!

 

[Protimenow]

If you test every 2-3 months, all you really know is that your INR is stable at least once every 2-3 months. This does NOT mean that your INR is consistent between tests, or that you are actually SAFE during those intervals between tests.

I once thought that, as long as my dosage and diet were fairly constant, I was always in range. It's not that simple.

Personally, I usually test once a week - at most, I might go two weeks between tests.

I also manage my dosage. I keep an 'INR Diary' - a spreadsheet with every test, my current dose, and any information that I think may be relevant to any fluctuations in my INR. I make my dosage changes gradually - if at all.

There's good material available that can give dosing guidance--and there are people on this forum that can tell you what works best for them.

I would no longer be comfortable letting more than a week or two to go between tests. Strips are relatively inexpensive. Meters can be pretty expensive -- but working meters can often be found, affordably on eBay and possibly other places. To me, it no longer makes sense to go for extended periods without testing.

 

[ski girl]

Playing 'devil's advocate' here Protime - if you test once a week, all you really know is that your INR is stable once a week . . . . Interesting that you're testing that frequently! Was that a decision you took, or that you've been told to go by?

 

[pellicle]

Hi

If you test every 2-3 months, all you really know is that your INR is stable at least once every 2-3 months. This does NOT mean that your INR is consistent between tests, or that you are actually SAFE during those intervals between tests.

Have you had to adjust your dose much or have you been relatively stable?

My adjustments have been in the order of 6mg daily to 7mg then back to 6 again, over a month or two. My adjustments were just to keep myself below 2.8 for no particular reason.

Probably the hospital stay had some influence on my INR.

Saturday is my testing day. I also put out the weeks Warfarin then too.

 

[pellicle]

Playing 'devil's advocate' here Protime - if you test once a week, all you really know is that your INR is stable once a week

Well to be fair its unlikely to vary much within 3 days without some sincere provocation.

Anyway your off the vodka grapefruits now I hear

 

[Cooker]

Once every month or so at my cardiologist office ... I do let it slip up on me and have gone as long as six weeks ... no stress over it... just lovin life ...

 

[newmitral]

Hi Ski Girl,

I believe the "standard" approach is:
once your INR has been stable for two or more months (with weekly or bi-weekly testing), the usual protocol is to test monthly.

However, I do agree with Protimenow that weekly testing is preferable - but it depends on your particular metabolism and how stable you have actually been. In my own case, my INR fluctuates wildly and I frequently go from 4.0 to 2.2 in the course of 1 week.

I home-test weekly with an Inratio-2 meter. From my weekly tests, I know that my INR fluctuations are much higher than typical (yes I keep my diet consistent), and therefore weekly testing is smarter for me. If you test weekly for a while, and see very little fluctuations, then spreading the testing periods out longer should be OK.

I rarely have to alter my dose much, but I metabolize warfarin much faster than typical, and it takes a lot to keep me in range (12.5mg/day). I believe this also contributes to the larger variations in INR that I have. I started taking low-dose K2 pills (60ug/day) to try to stabilize my INR, and that's helped a bit, but I still bang from upper-end to lower-end of my range within a few days. Not really a problem for me, but it has proven to me that in my case the weekly testing is very wise. Sometimes I will also test mid-week if I think my INR might be off for some reason.

My primary-care doctor officially manages my dose, but I have access to the standard dosing algorithms, and typically make the adjustment myself before his office calls to give the the same recommendation I am already implementing.

The meter manufacturers have studies which show that warfarin users who self-test weekly stay in range more than those testing only monthly, and have fewer stroke/bleed events. But, take that with a grain of salt since they have a vested interest in those results. For me, the home-testing is all about the convenience.

Hope this helps.

 

[dick0236]

Ski Girl, your profile suggests that you have a tissue valve(cow bits?). If that is true, why are you still on warfarin? If you are on it for a-fib, maybe once every couple months is OK. I have several neighbor friends on warfarin for a-fib and they test infrequently, like you. Mechanical valve patients, like me, take warfarin to minimize "throwing clots" that can cause strokes. In the "olden days", prior to the INR system, I had sometimes gone 2-3 months between lab draws....nowadays, with the convenience of the "finger stick" and personal meters, I now choose to test more often, currently weekly.

 

[Oilman]

Ski Girl,

Like Dick has mentioned maybe the use for Warfarin is different for some, I have a new shinny On-X valve, and was recommended by the surgeon to run my INR between 2.5 to 3.5 until further notice. This is something I pay close attention to as I suffered a TIA two years prior to my valve repair. Luckily I was not left with any lasting symptoms.

In the two years prior to valve replacement, I was only followed by the local hospital for three months for my dosing, then sent to my GP office, that didn't work out so well. At that point I was quit stable at 2.5 INR, and learned enough about dose adjustments. I was testing every 2-3 weeks at that point. I was using 75mg per week to keep in range. I self test with a CoaguChek XS.

Since valve replacement, the hospital that I had the surgery done at, has been managing the dose, I self test every two weeks and things are just getting back to the same requirement of 70-75 mg per week to keep in range. The testing every two weeks works out good for the test strips, as I buy a bottle of 24, that has a year to expire. I also pull a lab draw, try to every couple of months to check machine accuracy with lab, yesterday was bag on 2.7 for both.

In the beginning I was a little frustrated working with the girls at the clinic cause they wanted to increase so slow to get in range. Now they are working with me and allowing me to give them my opinion. Good luck with your testing.

 

[Protimenow]

Pellicle:

A few answers to your questions.

My INR has been pretty stable. I was taking 7.5 mg/day for many months and, for some odd reason, my INR started dipping below 2.5. I increased my dose to 8 mg/day (a really minor increase), and was right about at 2.5. I've run out of 4 mg warfarin, and I'm waiting for my MD to respond to the refill requests. What I've just started doing is 7.5 mg on odd numbered days and 10 mg on even numbered days. I'm testing my blood in about an hour, so I should have a pretty good idea of where this puts me in my range.

Personally, as long as I'm below 3.5, and above 2.5, I'm comfortable. Dosing adjustments have been small and infrequent.

(Oh, FWIW, your INR can drop dramatically if you've had a LOT of greens or taken moderate doses of Vitamin K -- the INR can drop in as little as one day; and if you're taking grapefruit juice, it can go in the other direction, amplifying the effect of the Warfarin)

 

[pellicle]

Hi

In my own case, my INR fluctuates wildly and I frequently go from 4.0 to 2.2 in the course of 1 week.

Wow

I believe this also contributes to the larger variations in INR that I have.

Interesting. For what its worth I had a highly variable INR within 12 months of my surgery (Nov 2011) and used to wonder if it was my body 'fighting' against the warfarin. I now have a much more stable INR and dosage. Perhaps its like a splinter that gets embedded deep in the skin and the body stops it hurting (loose analogy I know, but wanted a KISS metaphor)

.
The meter manufacturers have studies which show that warfarin users who self-test weekly stay in range more than those testing only monthly, and have fewer stroke/bleed events..

Not just them. If interested have a read of this article

Self-management of oral anticoagulant therapy: Asystematic review and meta-analysis Thomas D.Christensen a,⁎,Søren P. Johnsen b, Vibeke E. Hjortdala, J. Michael Hasenkam

Ten trials with a total of 2724 patients were included

Let me know if you can't get that and wanted to read it. I can send you a copy

 

[pellicle]

Hi

My INR has been pretty stable. I was taking 7.5 mg/day for many months and, for some odd reason, my INR started dipping below 2.5. I increased my dose to 8 mg/day

similar to the sort of tuning I do ...

and was right about at 2.5. I've run out of 4 mg warfarin, and I'm waiting for my MD to respond to the refill requests. What I've just started doing is 7.5 mg on odd numbered days and 10 mg on even numbered days.

I guess that your cutting tablets in half with the 7.5mg ... probably its common but I don't have much experience in what others do so I'll ask the 'obvious' question.

I use Marevan and its 1 ,3 and 5 mg tablets so I sometimes use a 5 + half a 3 to get my 7.5

I'm testing my blood in about an hour, so I should have a pretty good idea of where this puts me in my range.

after dosing? ??

amplifying the effect of the Warfarin)

essentially, yes. But for the quizzical it is actually because there is a enzyme in your gut which attempts to destroy things which it does not recognise as foods (potentially poisons). Grapefruit juice essentially inactivates this (barrier) enzyme and allows your body to absorb more of the warfarin (nb increasing bioavailability)

 

[newmitral]

Hi pellicle,

I'm coming up on my 2 year valversary, and in my case, INR hasn't settled down, but I've gotten comfortable living with the fluctuations. The past 6 months has been the period when I have been taking the low dose (60ug) daily vitamin k2 supplement and it has made the fluctuations a bit smaller - it was a bit worse the first year and a half. I don't worry too much on upside swings unless I'm above 4, and because I have a newer On-X vave, I don't worry much on the downside unless I hover at 2.0 or below. My official range is 2.5 to 3.5

To underscore the point made earlier, here is a plot of my INR and warfarin dose over the past 6 months or so. My mean INR is 2.96 which is almost perfectly in the middle of my target range. The standard deviation, on the other hand, is likley higher than most others see.

With variations like this, it is plain to see that getting an INR sample only once a month would easily lead to false conclusions, either to the good or to the bad, and possibly improper dose changes. If dose adjustments were made based on a monthly spike, I could be on a real roller-coaster. But, that's just me, as a result of my particular metabolism. With weekly testing, it isn't a problem, and I can compensate quickly for the occasional wild spikes in INR instead of letting them go for a prolonged period.

If you have a month or two of weekly INR test results, and you see a stable INR that doesn't vary more than a few tenths from week to week, then you are probably fine extending the test time to a month or perhaps more. The point I wanted to emphasize, which is the same point Protimenow raised, is that if you have the more fine-grained weekly test results you know what you are dealing with and can make an informed decision about your INR stability and the wisdom of going longer between tests. If you only have the monthly tests, you really don't know what might be happening in between. So, my recommendation to Ski-girl would be to take a month or two of weekly tests first, and then she will be in a much better position to know if monthly (or even less frequent) testing would be risky for her particular metabolism or not.


Thanks for the reference to the meta-analysis study. I think this was actually one of many papers I had already come across. I'm a bit of a research junkie like yourself.

 

[Protimenow]

Ski-Girl - sorry I missed your question. If I test weekly, I am still getting a 'snapshot' of what my INR is AT THAT MOMENT. However, my weekly INR should be fairly representative of what it was in the previous week. Also -- I'm at minimal risk of a TIA, according to recent studies, even if my INR is below 2 for as long as a week. Therefore, the weekly testing seems appropriate, because it can detect an INR that is below 2.0 - and give me time to do some remedial dosing modifications before I have a major problem.

The question about whether my blood draw was 1 hour after my dose -- no, I take my warfarin at bedtime - usually between 10 and 11 PM. The blood draw was actually taken at 2:50 PM--about fifteen hours after I took my warfarin.

Also - in response to another question -- no, I'm not breaking my 7.5 mg pills. I'm alternately taking 7.5 on odd days and 10 on even days. So far, according to all meters, I'm either slightly under range or right in the middle.

(On another matter -- I tested with three meters, because this may by my last blood draw for some time, and I haven't had a chance to compare the lab results to my Coag-Sense meter. Coag-Sense - 2.3. InRatio 2 - 3.0. ProTime 3 - 2.9. It'll be interesting to see which meter's result is closest to the lab's result. I should know Monday)

 

[pellicle]

Also - in response to another question -- no, I'm not breaking my 7.5 mg pills.

I guess you missed my point. Di you have pills that are 7.5mg?
My tablets are 1,3,5
These is no fraction without breaking them

 

[pellicle]

My official range is 2.5 to 3.5
...
To underscore the point made earlier, here is a plot of my INR and warfarin dose over the past 6 months or so.

That's some interesting volatility.

I assume this is weekly readings? Sorry to say this but reading stuff like this does me good as my variations were never as serious as these. I now feel that my variability was minor and QML (the lab that did my warfarin monitoring and dosing) was less problematic.

Out of interest do you have any theory on those spikes?

 

[newmitral]

I assume this is weekly readings?

Yes, the date is written sideways at the bottom. I test every Saturday morning. The only data point that is not a weekly test is the data point on Wednesday 2012-11-14 which shows INR=2.8 in between the 4.4 and 4.3 readings.
I had lowered my dose to 1/2 dose Saturday night after the high reading of 4.4, and took a few extra K2 pills to quickly lower my INR. Also, I did a blood draw that Wednesday and wanted a meter test the same day to compare to the lab (Lab was 2.9, meter was 2.8).

Out of interest do you have any theory on those spikes?

Not surprisingly, my doctor has asked the same question. The only thing that I can think of that could possibly be related to the two 4.2/4.3 spikes on 2012-11-10 and 2012-11-17 was that I drank some cranberry juice the days before those readings. It is controversial whether cranberry juice can actually effect INR or not, and I may be one of the few that is sensitive to it. I plan to do a more rigorous and systematic study of cranberry juice versus my own INR sometime in the future, but for now I'm avoiding it.

I have absolutely no idea what might have caused any of the other spikes, many occurring before the period shown on the chart above, that seem to happen for no apparent reason. I do try to be consistent in my diet, and things used to be slightly worse before I started with the daily low-dose k2 to help keep the level of "k" in my system a bit more uniform since I don't eat a lot of greens. There are several studies that indicate low dose k2 can help folks with highly variable INR like mine to level out a bit. While it has helped, it is still a pretty wild ride, but I'm used to it. It does highlight the fact that for folks with highly varying INR, like myself, the weekly testing is a good idea.

I guess you missed my point. Di you have pills that are 7.5mg?
My tablets are 1,3,5
These is no fraction without breaking them

Here in the states, we have pills of 2.5 and 7.5mg in addition to the integer values of 1,2,3,4,5,6 & 10mg.
See this link which gives the standard warfarin pill doses and colors

http://healthcare.utah.edu/thrombosis/patients/warfarin/warfarin_guide_taking.html

I take 2 of the 6mg pills and break a 1mg pill in half to get the extra 0.5 when I'm taking a 12.5mg/day dose.
That makes it easier to adjust between a 12mg/day and 12.5mg/day dose.

 

[gerrychuck]

I am assisted in dosing by the local Warfarin Management program. Originally I went to the hospital for blood draws, first every few days, then weekly, then every 2 weeks at which point my INR was very stable. That all changed again when I went off amiodorone and simultaneously started increasing activity, which required a process of ongoing dosage increase over about 2 months, with weekly testing, until things stabilized again. During that time I switched to home testing with an InRatio2, calling in my results to the Warfarin program, going back to weekly originally, then 2 weeks. I test weekly at this point but only call in every 2-3 weeks as my test results haven't varied by more than .1 for the past month. If it stays this stable, I'll probably start going longer between tests, but not yet; as others have stated, weekly testing really isn't terribly onerous and gives me a little more confidence. I have compared my home test and lab test results once, and they were within .1 of each other. I intend to visit the lab again in a couple of weeks to recheck the correlation, but I'm pretty confident in the results I'm getting based on that initial comparison.