'per patient year' question

[dick0236]

So I never asked about in my urine

It's brown to reddish brown. I've had it happen twice.
Once in the early 1970s after several days of heavy drinking. A shot of vit K cleared it within a day or two.
The second time was on vacation in Spain in the early 1980s which, I think, was due to drinking and diet changes. I was too scared to go to a Spanish hospital for a vit K shot (I don't speak Spanish) so I stopped all drinking and watched my diet.....and drank a lot of water for the remainder of our trip. When we got back home my PT (the anti-coagulation test before INR) was within my PT range.

Those are the only two times over all of the years I have been on warfarin when I have had blood in urine. Both of these events were during the "dark ages" of warfarin management. Now, with the INR system and "home testing"........and a much better professional, and patient, understanding of ACT most of the old issues with warfarin are no more.

 

[Daniel758]

That statement still reads wrong. Assuming the risk is 2%, by year 30 the probability is still 2% in that coming year.

The probability that something might have happened over the prior 30 years is 45%. But it’s not 45% in year 30 if you happened to have no issues in the prior years. And it’s not 0% either if you’ve already had one. It’s still 2%.

Thank you for the clarification but did you not read my previous posts?

If so, I'm not sure why you think I was/am arguing that the risk specifically for year 30 or any other specific year was 45%.

I believe I clearly spelled out the 45% was the risk over the 30 year time period and the 2% was for each individual year. I even exactly stated that individual years risk does not change.

I'll have to assume you haven't read the posts or didn't understand what I was saying (or you were too emotional/upset?) so I'll copy and paste them below so you can see that I had made it clear multiple times that the risk for any particular year was 2% but the risk over the 30 year time period was 45%.

I even provided the formula and calculated the 45% over the 30 year period. Seriously, read my first post. That's what it was all about.

Where did you think the 45% over the 30 year period came from?

Do you realize that the .98 number I used in the formula came from subtracting the 2% yearly risk from 100%?

This was also the very reason why I said that you were incorrect when you told the original poster that his odds of encountering a bleeding event was 2% over the 30 year period he was asking about when they were actually 45% over this period.

What I am glad to see is that you seem to have now fully grasped this concept that the probability over a time period differs from the probability over an individual slice of time within that time period.

It's a good thing and should help you avoid giving out bad information in the future. Win for everyone here.

Now to the posts... with helpful highlighting in bold to help you find the relevant information... and a note on the probability formula...


This was my first post to the original poster who was asking for the odds of having a bleeding event over a 30 year period:

"The answer is:

1 minus the probability of the event NOT happening

(1-(.98^30))100= 45% over 30 years at 2% per year.

(Helpful highlight: Superman, the above is the formula for probability of an event happening over multiple years, not for a specific year, and is where the 45% number comes from. Please note the "over 30 years" and the "2% per year" mentioned as inputs for the formula.)

So a little less than half of people receiving a mechanical valve should be expected to encounter a “stroke or bleed” event at some point over a 30 year period.

If the risk of stroke or bleed is lowered to 1% the answer would be roughly 26%, much better and why it’s important to keep your INR in range.

Note: Your probability of having an “event” is not 50-50 on the specific year 35, your probability of having an “event” is 50-50 by the time you reach year 35.

The longer the time period, the higher the probability that the event will happen within that time period."



This was my second post responding to you specifically:

As far as stats, they aren’t cumulative like that. I’ve been event free for 32 years on warfarin. There is still a 2% chance this year of an event just like there was the first year I received my valve. But that’s a 2% chance among all patients, not me individually.

"Yes, your chance this year is still 2% but your chance of having had a bleeding event over the last 32 years was around 48%. Essentially a coin flip and you did well.

Over the next 32 years, your chance of having a bleeding event is also 48%. I wish you luck once again on that coin flip.

Note: 1-(probability of not having an event ^32) is 48%

If they were cumulative, our friend @dick0236 would be having adverse events annually right now (55 years on warfarin) at a 110% chance! He’s at the same 2% risk.

No, Dick's chance of encountering a bleeding event over 55 years was around 67%, not 110%.

Note: The percentage will never go over 100% (and it's not linear). Look up Limit Theory in any first year Calculus book for why this is.

Think if it this way. X% of people die in car accidents annually. Now that you’ve been driving 30 plus years, do you feel like any time now you’re going to die when you get in a car?

Again, no. See above.

Superman, you're a reasonable guy, can you not see that this is a perfect example of why it's not a good idea for you guys to give out medical advice on this forum?

What you believed and offered as fact actually isn't fact.

What other "facts" are you guys giving out that aren't facts either? And how would you know?

Don't you think telling this guy that his chance of a bleeding event (significant or not) over a 30 year period is 2% when in fact the probability is actually 45% could make a difference in his decision making?"



My third response to you:

You’re reading me wrong. I was saying if this misconception (odds increasing every year) were true, then….

But it isn’t true. This year, like any other year, it remains roughly a 2% chance (assuming that statistic is accurate). Of course I don’t think anyone has a 110% chance of a negative event.

I don’t disagree with the statistics as you say them and I don’t see how they disagree with any point that I’ve made. I also don’t see where I gave any medical advice beyond what you did (aiming to clear up a statistical misunderstanding) so get off your high horse please. Your incessant beating of that drum is more than obnoxious at this point.
Click to expand...

"You may be reading the original poster wrong.

The original poster was asking what his risk was over a 30 year period based on a risk of 2% per year, not simply for year 1 or any specific individual year within the 30 year period.

Your answer of 2% was incorrect and bad information if the poster was to rely on this information to make his valve decision.

(Again, the odds for the individual year doesn't increase but as the number of years increases, the probability of an event occurring in the total number of years does increase.

That's how the probability of 2% the first year increases to 45% by year 30 and grows higher with each year after.)

Have a good day."



End of posts.


To wrap this up, I will take responsibility for not adding any wording specifying "30 year time period" at the end of the sentence italicized above that you seem to be referencing. My bad here.

The 30 year time period is alluded to in the sentence above the italicized sentence you have issue with and specifically stated in the sentence 3 sentences above the italicized sentence... and mentioned multiple times and the entire point of all three of my posts on this subject but I still should not have expected you to make this connection.

So yes, I agree with the 2% per year risk and the 45% risk is 30 over the year time period, especially since I explained this and provided the formula and calculated this number out in my original post for the original poster.


P.S. Superman, you're better than this and I expected a better effort, this was little more than grasping at straws here.

 

[Superman]

To wrap this up, I will take responsibility for not adding any wording specifying "30 year time period" at the end of the sentence italicized above that you seem to be referencing. My bad here.

That was my only point of contention. Not with the math. Words mean things and it’s especially hard over the written word to, “Hear what I mean, not what I say.” I have no disagreement with any of the probability math as presented.

You really didn’t need to repost. The original is still there.

But as stated previously, and not just to you but for the discussion as a whole - it would be helpful to know what gets recorded in that 2%, how does that compare to the general population of similar events (or particularly post valve surgery/non-ACT tissue valvers), and finally would a typical recorded event for that stat still be preferable to facing another valve replacement down the road?

And since most valvers are over 60 and we’re talking 100 patients for one year each (or whatever combination of age/patients/years they used in the study), how does that really translate to one individual who may be well under 60 for 40 plus consecutive years?

So in the end it still all boils down to being comfortable with whatever future condition management issues your choice will lead to. And it’s why we all have to be careful with words so we don’t either instill excess fear or downplay certain realities (or potentialities).

 

[dick0236]

So yes, I agree with the 2% per year risk and the 45% risk is 30 over the year time period, especially since I explained this and provided the formula and calculated this number out in my original post for the original poster.

Why don't you calculate the probability that a tissue valve will need to be replaced in thirty years? My "gut" says it will be much higher than 45%......... probably very, very, very close to 100% ??........so, "youse has your druthers and youse takes your pics".

 

[pellicle]

Why don't you calculate the probability that a tissue valve will need to be replaced in thirty years?

...because it's easier to criticize than examine yourself and make enemies than friends. Looking at yourself and your own decisions honestly is often harder than picking faults with others.

 

[Survived03]

The stool color reminds me of a good laugh that I had with my PCP. The question was “… clay colored stools?” I paused and asked him to describe clay color? I have lived in parts of the US where you have red earth clay, grey modeling clay, black and brown earth clay. So which is it? he laughed and so did I. Come to think of it I’m not I still know what too look for besides something really abnormal.

 

[pellicle]

” I paused and asked him to describe clay color?

hearty LOL

:-D

... Come to think of it I’m not I still know what too look for besides something really abnormal.

well

• black and tarry (in a small section even) which implies a bleed further up that's had time to go through the intestine
• black or dark brown as a section
• actual red blood that stains the water if its an ongoing bleed and in the lower bowel

I've actually seen that last one in someone who had a perforated bowel from a colonscopy (who wasn't on warfarin)

 

[oo0My_Valve0oo]

Thank you all for hashing these points of view out. Contrary to voiced opinion this exchange offers clarification in use of different words and approaches to ideas and information. I disagree with the notion put forth that written words are harder to "hear what someone is saying." Communication short of telepathy is an approximation usually distorted by degrees of emotion both positive and negative. Math has never been my talent. I get what is being discussed but not to a point I would argue over it being mathematically correct or incorrect. In many contexts people can come up with seemingly strong support for anything. It is done in legal cases with expert witnesses appearing on both sides. But it all goes south with labeling and name calling and profiling specific people as though you could know their feelings and motivation to present it while encouraging people to ignore that person out in the open or via private messaging. If it is your psychic impression you really need to declare that. Otherwise it is conjecturing presented as fact. At that stage you tarnish your own credibility because not only is it petty, destructive and off topic it is a tactic used to undermine an opposing POV wrong or right. Get people to doubt someone's character and their presentation could be perfect but it will suffer because of it. That is fighting dirty. There will be disagreements. If anyone fights dirty the relationship is doomed whether it is forum discussion, business, friendship, marriage, and so on.

 

[oo0My_Valve0oo]

It's brown to reddish brown. I've had it happen twice.
Once in the early 1970s after several days of heavy drinking. A shot of vit K cleared it within a day or two.
The second time was on vacation in Spain in the early 1980s which, I think, was due to drinking and diet changes. I was too scared to go to a Spanish hospital for a vit K shot (I don't speak Spanish) so I stopped all drinking and watched my diet.....and drank a lot of water for the remainder of our trip. When we got back home my PT (the anti-coagulation test before INR) was within my PT range.

Those are the only two times over all of the years I have been on warfarin when I have had blood in urine. Both of these events were during the "dark ages" of warfarin management. Now, with the INR system and "home testing"........and a much better professional, and patient, understanding of ACT most of the old issues with warfarin are no more.

Hello dick0236,

Your signature states no diet restrictions. I have a bio tissue valve and was on Warfarin for the first three months following surgery. The Coumadin clinic people encouraged me to stick with the same foods and to eliminate some vitamins. Granted the hospital gave me vitamins and a bottle upon release as well. It was specific vitamins not vitamins in general. Eating the same diet may have only made their job easier by being consistent. Some food significantly impacts coagulation management. At the very end my figures went off what they had been and we could not figure it out before they just decided it was time to release me from the program. This was to be a limited period and once they found a happy place to hover they made minor adjustments at least every other week and I was eating similarly the whole time until the last two weeks. At the end I was tired of the same thing and ate other foods. It showed up in my INR. Maybe it effects people differently. Has your diet been relatively consistent and Coumadin friendly?

 

[dick0236]

Has your diet been relatively consistent and Coumadin friendly?

I have never been advised to stop eating, or drinking, anything and I have always enjoyed a typically southern diet. That said, I do not pig out on cooked greens like kale and spinach, but I do eat them occasionally and I eat salads several times a week. Recently I have begun to drink an 8oz BOOST daily which does seem to lower my INR a tad.....so I increased my warfarin a tad.....+2.5mg/wk(+7%).

The standard advice for anyone is "dose the diet....don't diet the dose". I have never known any foods that have had a dramatic effect on my INR.

 

[pellicle]

The Coumadin clinic people encouraged me to stick with the same foods and to eliminate some vitamins.
...

Has your diet been relatively consistent and Coumadin friendly?

I can only say more harm is done by these clinics than can be properly estimated:

The reality is well summed up:
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC4998867/

In conclusion, the available evidence does not support current advice to modify dietary habits when starting therapy with VKAs. Restriction of dietary vitamin K intake does not seem to be a valid strategy to improve anticoagulation quality with VKAs. It would be, perhaps, more relevant to maintain stable dietary habit, thus avoiding wide changes in the intake of vitamin K. Based on this, until controlled prospective studies provide firm evidence that dietary vitamin K intake interferes with anticoagulation by VKAs, the putative interaction between food and VKAs should be eliminated from international guidelines.​

Fairly straight up really. Although its up to you if you regard "stable dietary habit" as meaning stick with the same foods. Of course you could always decided to "stick with good foods".

I do realise however that if the above were said (even with citations in proper academic process) by just some random dude on the Internet it would be in violation of the scriptures in the Book of Daniel. Never trust anyone who isn't at least a doctor ... wait ... are the clinic staff doctors?

 

[carolinemc]

I have never been advised to stop eating, or drinking, anything and I have always enjoyed a typically southern diet. That said, I do not pig out on cooked greens like kale and spinach, but I do eat them occasionally and I eat salads several times a week. Recently I have begun to drink an 8oz BOOST daily which does seem to lower my INR a tad.....so I increased my warfarin a tad.....+2.5mg/wk(+7%).

The standard advice for anyone is "dose the diet....don't diet the dose". I have never known any foods that have had a dramatic effect on my INR.

What about taking antibiotics, for it can raise mine and on warfarin. They tell me at the lab I go to that I could a little salad, but I don't that enough. And have to be careful with OTC for colds and allergies, for they also can affect the INR.

 

[pellicle]

What about taking antibiotics, for it can raise mine and on warfarin. They tell me at the lab I go to that I could a little salad, but I don't that enough

taking antibiotics can raise INR ... which brings us back to the benefits of self testing. Just test and adjust as needed, when you finish the course you can assume that you can go back to your pre-antibiotic dose (and test to confirm this occurs).

usually variations are minor and the INR changes are observable but not threatening.

 

[carolinemc]

taking antibiotics can raise INR ... which brings us back to the benefits of self testing. Just test and adjust as needed, when you finish the course you can assume that you can go back to your pre-antibiotic dose (and test to confirm this occurs).

usually variations are minor and the INR changes are observable but not threatening.

I have no way to do at home testing, no machine and on Medicare in the USA. But today at the lab, it also treat cancer patients at the H & R Block cancer center, got a great INR reading of 2.9. Still in the safe zone. Have a great Turkey Day.

 

[Survived03]

I apologize if this has been posted previously, but one thing to consider when beginning warfarin therapy might be a persons genotype and their association with warfarin metabolism.

https://www.ncbi.nlm.nih.gov/books/NBK84174/

 

[DJ-Rae09]

but be on warfarin and have a significant risk of a stroke or bleed hanging over me for the rest of my life.

Hi mate, I'm fresh into Wafarin therapy and INR self management. Yes the chances of a stroke or bleed are there, but if you manage your INR at home and keep it in range majority of the time, the risks are low as outlined in previous posts here.

I was fearful of being on Wafarin for the rest of my life prior to surgery too, I've since learnt its no big deal. I eat and drink (I like my beer) what I want. My INR test at home takes 5 mins per week. My target range is 2.5-3.0, on the odd occasion I've had a reading of 3.5, 3.4 and 3.6 but this is still super safe and I just drop the dose for one night and I'm back in my range.

If you decide mech valve, I'd recommend getting an INR self management device and start logging each test to gather data. This will help you learn about how Wafarin works with you and what dose to take etc.

@pellicle has an excellent spreadsheet to track your INR and make dose adjustments if you go outside your range.

Good luck with your surgery too

 

[tom in MO]

I have no way to do at home testing, no machine and on Medicare in the USA. But today at the lab, it also treat cancer patients at the H & R Block cancer center, got a great INR reading of 2.9. Still in the safe zone. Have a great Turkey Day.

Home testing is covered by Medicare. Talk to whoever prescribes your warfarin.

 

[carolinemc]

Home testing is covered by Medicare. Talk to whoever prescribes your warfarin.

Does it pay for the machine and strips and I do not have to pay for it? Just asking. And the lab is at Truman/UH Health center, a teaching school and the lab does not do the billing, finance does.

 

[pellicle]

but one thing to consider when beginning warfarin therapy might be a persons genotype and their association with warfarin metabolism.

agreed and if this has been discussed before is not a matter for apology ;-)

The problems with this are:

1. cost benefit (administration will want to see that proven)
2. getting it done; its not a common test at all and is something that's more or less restricted to pathology labs that specialize in meeting the needs of science not medicine.
3. its genetic testing, which some people may have ethical reservations about (and indeed concerns that their DNA will remain private)
4. getting that information to the clinic or to the hospital team who will be setting your initial dose. I'm pretty confident that they are not set up for that
5. Assuming they get that they'll have administration procedures which will discount (ignore) that data and say "we've never done that before" (so how will it ever get included if its never done?)

The reality is that even with that genotype there may be phenotype variances which will likely result in the need to titrate the dose to the patient anyway. Take me, my dose can vary between 8mg a day to 5.5mg a day and I'm me all day every day (try the beef). Further I was 4mg when I left the hospital.

A good intro for anyone who's new to that topic of phenotype:
https://en.wikipedia.org/wiki/Genotype–phenotype_distinction

The genotype–phenotype distinction is drawn in genetics. "Genotype" is an organism's full hereditary information. "Phenotype" is an organism's actual observed properties, such as morphology, development, or behavior. This distinction is fundamental in the study of inheritance of traits and their evolution.​

 

[tom in MO]

Does it pay for the machine and strips and I do not have to pay for it? Just asking. And the lab is at Truman/UH Health center, a teaching school and the lab does not do the billing, finance does.

I don't know the specifics. My mother-in-law received her device and supplies through Medicare. How much is paid for may depend upon your supplemental plan.