Frequency of INR testing

[Guest]

There is a lot of good anticoagulation research that comes from Italy.

One that was just published recently found:

For patients in stable condition with a prosthetic heart valve who are monitored at an anticoagulation clinic, a 6-week interval between INR determinations does not increase the ... risk of thromboembolic or hemorrhagic events.

The interval between tests at my clinic averages about 40 days, so I pretty much agree with this.

 

[ccrawford]

Al - Your clients must be a lot more consistent than some of us. I'm usually happy if I get out to a month between tests. With changing meds, apparent diet variations and Rain's dog digging in the garden, ProTime continues to enjoy a steady cash flow from me.

 

[EVELYN]

Boy, Chris, I agree with you!!! Tyce went from a year of being fairly stable to wild swings. Right now we're in a down mode....and we still haven't figured out if it was the machine or the strips.....or maybe even Rain's dog!!! He tests every week at home and then since he's been so crazy every two weeks at the cardio.....Yes, Virginia, there are Pin Cushions!!!

Of course the weather has been crazy here, so we really haven't had a chance to walk much, which I think affects that inr, too.....Just hope we get it figured out before the holidays!!!

Ev

 

[Rich]

INR Range

INR Range

Al,
A question for you.
My INR's have been steady as a rock for well over seven years and from some of the posts I guess I've been very fortunate, until lately.
In the last two months Iv'e been running on the low side, anywhere from 1.7 to 2.0.
I havn't changed my diet, medications, etc.
What I have done is keep extremely busy doing a LOT of home improvement since I retired.
The only real change is I've lost about 12 pounds in the last few months(and I can't really afford it since I was always on the thin side).
Could the weight loss and the heavy activity have any bearing on my INR ?
Rich

 

[Nancy]

Joe is also one who has become unstable. He used to be in range most of the time, but lately has been fluctuating quite a bit. It might be related to his CHF which seems to cycle every 10 days or so. He is also much more active than he's been for a while and has recently added Neurontin (for shingles pain) to his drug mix.

Everything combined is making regulation a little more difficult.

 

[Guest]

You have hit it right on the head as far as activity is concerned. Changing to less activity causes the INR to go up and increasing activity causes the INR to go down. It has to do with getting the heart rate up (down), then more (less) passes of blood through the liver so warfarin metabolized more (less) hence the change in the INR.

Weight gain or loss is not the actual culprit but the marker that you have made a change.

 

[bvdr]

So then, Al, when you add a Beta Blocker (that reduces your heart rate) it is expected that the INR would rise?

 

[Rich]

Another question for Al

Another question for Al

Al,
Thanks for the info.
I guess my choices are to sit and do a lot less or keep going and make some minor adjustments.
I am not the type to just sit, I beleive retirees who do that are going to be around too long.
So as long as I'm physically able I'll keep going like I have been.
Now for that question.
I currently take 5mg on M,W,F and 2.5mg the rest of the days for a total of 25mg per week.
I think you said that adjustments should be about 10% of that total.
How would I make that change based on the days I take each dosage?
My cardiologist just insists that I do a blood draw every two weeks at this time.
I have to convince him of the circumstances that are causing the problem.
He also feels that those of us with a mechanical valve should be in the 2.0 to 2.5 range.
What do you think?

Rich

 

[Guest]

Beta blockers present an interesting problem. Slowing the heart can mean more efficient pumping which can lower the INR. This isn't an exact science.

If someone was taking 25 mg/wk, I would probably go up about 2 to 3 mg/wk if they were less than 0.5 units out of range.

I know of no evidence for keeping someone in a range that is only 0.5 units wide. An atrial valve could be kept in that range. If you self-test and self-adjust it should not be that hard.

For many of my patients who have to drive 50 to 100 miles one-way to the clinic keeping in such a narrow range would mean lots of extra trips.

 

[Jan]

Hi Al

Your post is very reasuring to me,

in the UK we are usually tested every 4 weeks ( unless you have had a dose change ) then it is weekly

I have been quite stable at 3.5 for almost a year, except when i came back from the US when i was 5.0

I was concerned as i have lost a lot of weight 62lb but thankfully my INR has stayed at 3.5

now they are suggesting that I go on 6 week testing,

If I have any concerns( bruising etc ) I can go for a test right away

Thanks

Jan

 

[Guest]

Jan, Good to hear from you again.

As you noted, breaks in your routine lead to INRs out of range. A 5.0 after a holiday is not unusual.

Congratulations on the weight loss.

 

[Gail in Ca]

the report I read said that ones INR stays more in range if tested weekly, and I will continue to do this. I am used to this, and frankly would not want to test only every 40 days.
Gail

 

[Guest]

I'm not trying to talk anybody into changing their routine. I just like to point out differences in what works.

There are two problems with time time in range as a marker.

1. The definition is very arbitrary. Do people get a grace period to get started and in range? If so how long? 30 days is common. Is in range exactly the defined range? Is there a close enough range? I use + or - 0.2 INR units as close enough. Others might use 0.3 units, maybe even 0.5 units. f your doctor has you hold warfarin for a procedure, and you get tested just before the procedure are you in the range or not? You are where your doctor told you to be but you are out of range for your primary condition, so where are you recorded for that day. What if you test every day until you get back in range? All of those tests add to the percentage of tests out of range?

2. Because of all of the variances mentioned in #1 it makes it very difficult to show that time in range correlates with good or bad outcomes.

I use time in range as a quality assurance marker in my clinic but it whenever someone wants to know what it is, I point out the reasons that it is not a very valid marker.

Also it is not only whether you are in or out of range but the magnitude of the variance. One day at an INR of 100 is probably worse than a year at 3.6. But nobody has proven this and they never will because it would be unethical to put a group of people at an INR of 100 to see what the risk is.

The take away message is get the facts and then see what you feel comfortable with. It is like driving. Some people would never go 5 mph over the speed limit and others see anything that doesn't cause a wreck as acceptable.

 

[bvdr]

Hi Al,

Just curious about a couple of things. How often do you see very high INRs and what is the highest you have ever seen in your practice? Thanks.

 

[ALCapshaw2]

Hello Rich,

We take roughtly the same dose on a weekly basis.
I chose to take 3.5 mg daily using a 3.0 mg tablet and half of a 1 mg tablet and occasionally take 4 mg once a week if my INR is on the low side. Unfortunately, my co-pay is the same regardless of dose. Bummer. Too bad they don't make a 3.5 mg tablet!

This approach comes to 24.5 mg / week (3.5 X7 = 24.5). I prefer to use a daily dose closer to the desired average than to alternate between high an low doses 'hoping' to hit the average.

'AL'

 

[Guest]

CoaguChek currently only gives readings up to 8.0. It did register to 9.2 but they changed the system. The tester in the hospital will go to 11.2.

When it goes above that accuracy is pretty much meaningless.

My rule is to treat anybody who is bleeding and to just hold warfarin on anyone who is not bleeding. People who are greater than 8 get a "fire drill" of what to do if they start bleeding.

I have had doctors tell me about people who have had INRs in the 50 to 100 range who had no harm done.

 

[bvdr]

I remember several years ago when a golden retriever we had got into some rat poison. One day I noticed little specks of fresh blood on the porch and saw a drop fall from his mouth. The vet said that the kind he got into was especially long acting. I ended up giving him Vit K injections for several days and he ended up being alright. I imagine rats on autopsy would have really really high INRs. What do they do to rat poison to make it "long acting?"

 

[Guest]

I suppose that they altered the molecule to reduce the rate of metabolism by the rat liver.

This would not necessarily be a good idea for people - the goals of treatment are "slightly" different.

Have you all noticed that Hank has a store selling merchandise for a fund raiser? It is at http://www.cafeshops.com/valvesreplaced

I took the idea from Hank and started one, also. It is at
http://www.cafeshops.com/warfarinfo

I gave Hank as a referral so he should be getting some kind of credit so I didn't just steal from him.

 

[Ross]

Have you all noticed that Hank has a store selling merchandise for a fund raiser? It is at http://www.cafeshops.com/valvesreplaced

I took the idea from Hank and started one, also. It is at
http://www.cafeshops.com/warfarinfo

I gave Hank as a referral so he should be getting some kind of credit so I didn't just steal from him.

Ah but you offer one item that we don't. I bet that one item sells pretty well too!

 

[Guest]

Actually it does not. All it generates is laughs when I show it. If somebody had nerve enough to order it, I would be amazed.

Hank should get about 4% of your purchase price from orders through my store.

If any of you ordered something, I would appreciate feedback as to whether or not you think the quality of the merchandise is worth the cost.