Potential for future bleeding event on Coumadin

[ks1490]

Hi,

Are there some old posts or has anyone done any research on the potential for future internal bleeding events, not caused by lifestyle or injury? My cardio has said that the probability of a bleeding event increases by 1% per year, and it is cumulative - so after 40 years (in my 40s now), the probability of a bleeding event is 40% by that math. Has anyone heard anything different, or could you point me to some research on this subject?

Thanks.

 

[catwoman]

I'm sure Al Capshaw and others will be online soon to throw water on this claim.

I've never taken statistics, but some folks here say the stats that doctors throw out are mathematically impossible. I'll let them explain.

 

[dick0236]

My cardio has said that the probability of a bleeding event increases by 1% per year, and it is cumulative - so after 40 years (in my 40s now), the probability of a bleeding event is 40% by that math. .

You will find several threads on this subject on this forum. I have never had a cardio or PCP mention this kind of "cumulative" risk. Maybe they have tried to "protect me' since I've been on coumadin/warfarin for over 42 years. It makes sense that, with age and other health problems, the risk of a "bleeding event" will increase, but not in a cumulative way. If such a statement could be true, why in hell would any younger person (under 60) put himself, or herself, at such a high potential risk by choosing a mechanical valve. I would suggest that your cardio "put his mind in gear before he puts his mouth in motion" Incidently, your guy is consertative, some have posted that their doc says 2% to 5% on a cumulative basis.

 

[river-wear]

You might have better luck with this post in the anti-coagulation part of the forum. I've been researching this same thing and found that the risk rises with age, but like Dick said, it is not cumulative. Statistically, the argument doesn't make any logical sense.

Michele

 

[Philip B]

Cumulative Risks

Cumulative Risks

This is a topic that has been the focus of lengthy past discussion here. Others may disagree, but my perspective is that the cumulative affects of coumadin increasing potential internal bleeding disorders is more myth than fact. Associating a 1% cumulative increase per year seems like an major generalization.

Hopefully, some of our members who are more into keeping up with the formal research stuff will jump in here and share some resources with you.

I do agree that age probably increases the chances of internal bleeding just as the risk of broken bones increases with many people as they get older. A lot of health issues surface as people age.

-Philip

 

[dl_mooney]

Never heard of that,Im 71 years old.I also have the OnX Valve & it uses a INR of 2.0-3.0 so dont need as much Warfarin.

 

[westie]

who said that?

who said that?

.I also have the OnX Valve & it uses a INR of 2.0-3.0 so dont need as much Warfarin.

like you , i also have the on-x valve in the mitral position and the surgeon told me i needed an inr of 3 to 4. (he also told me not to listen to anyone advocating a lower range) i also remember reading on a number of occasions that a range of 2.5 to 3.5 was recommended.

but i have never seen an inr 2 to 3 recommended for the mitral position; a range of 2 to 3 seems to be the one recommended for aortic implants?

personally i would be panic stricken if my inr was 2

 

[Ross]

It is NOT cumulative. If it were, every one of us would have an event of sorts by now and it's a mathematical impossibility.

You might do well to take a look at this:
BETWEEN 1998 AND 2004 AN AVERAGE OF HOW MANY PEOPLE PER YEAR

IN THE UNITED STATES BLED TO DEATH FROM AN

OVERDOSE OF WARFARIN?

Make your guess then click to see the answer.

As a side note, IF YOU ARE PROPERLY MANAGED, your risk of an adverse event is near 0%. It's people that are not properly managed, noncompliant, or just not cared for properly, that run into trouble.

 

[ALCapshaw2]

Here is the most definitive answer to your question as posted by Bradley White to another member several years ago. Note that Bradley teaches (taught?) Statistics to PreMedical Students at Notre Dame University. FWIW, I understand and concur with Bradley's Analysis given the assumption that the Annual Risk is Constant.

Andyrdj also addressed the mathematics and statistics in a thread you started on June 19, 2006 "Question on Probability of later problems due to Coumadin" in the Valve Selection Forum.

'AL Capshaw'

Quote:

I cannot stress that when risk for ACT complications is given on a "per annum" basis it is not to be taken as cumulative. This is true of any statistic which is laid out as "the risk per patient year is X%". This is a quite basic principle in all biological sciences, especially medicine. I find it astounding that any surgeon would try to say the risk is cumulative!!!! It just makes no sense.
Scary how little medical professionels understand about basic statistics.

If risk were cumulative then that would imply at a risk rate of 3% at 35 years of anti-coagulation the risk would be greater than 100%. This simply isn't true or possible, it is not how statistics works. These risk events are always observed in patient years, one could not reasonable extract that data and attempt to add it up and say that after 35 years everyone would have had an event. That's simply not how statistics works. Anything whose risk is finite in a per year basis will never be 100% over any course of time. It will approach 100% but never reach it.

The cumulative nature of anti-coagulation risk is that every year there is a 3% risk. That means that every year there is a 97% chance of not having an event. As time goes on the chances that you won't have experienced an event decrease due to the recurring risk of 3% per year. You can calculate this risk by taking .97 and using the amount of years you are interested in as the exponent and then subtracting that number from 1 to figure out your chances of HAVING an event in X years:

I have made the following calculations based on a 1%, 2%, and 3% risk at 10 thrugh 50 years. The number represents the chances that you WOULD experience an event by this year if you were on ACT for mechanical valve.

AT THE 1% RISK LEVEL

10 YEARS = 9.6%

20 YEARS = 18.2%

30 YEARS = 26%

40 YEARS = 33.1%

50 YEARS = 39.5%

AT THE 2% RISK LEVEL

10 YEARS = 18.3%

20 YEARS = 33.2%

30 YEARS = 45.5%

40 YEARS = 55.4%

50 YEARS = 63.6%

AT THE 3% RISK LEVEL

10 YEARS = 26.2%

20 YEARS = 45.6%

30 YEARS = 59.9%

40 YEARS = 70.4%

50 YEARS = 78.2%

If anyone doesn't understand how I calculated those risks I can send them the excel file. The thing that stands out the most is the huge long term risk change when one goes from a 1% per annum event rate to a 3% per annum event rate. At 30 years, less than half of those at 3% per annum event rate will have not experienced an event, while at the 1% per annum event rate 74% of individuals should not have experience an event. This a significant reduction in the long term risk of anti-coagulation and represents the major medical reason why self-testing is such a huge advance since it has been shown to decrease the event rate from the 2-3% per annum category to around 1% per annum.

Trust me surgeons and doctors are not infallible, especially when it comes to math. I teach pre-med students a 300-level Fundamentals of Genetics course (decent working knowledge of statistics) at Nortre Dame and it scares me to death to think that some of them could one day be my doctor based on their complete incomprehension of statistics (among other things) at this point in their eduction.

Brad
__________________
Ross Procedure, Dr. Quintessenza, All Children's Hospital, St. Petersburg, FL -- 9/12/2000

Aortic Root and Valve Replacement with 23 mm Homograft, Dr. Joseph Dearani, Mayo Clinic, Rochester, MN -- 12/7/2006

End Quote

 

[river-wear]

Al, thank you for a very informative and helpful post. I hate to nitpick, but there is one word off in your summary, or perhaps I misunderstood.

This does NOT mean that the risk is CUMULATIVE, it only means that the annual risk X N-years is higher.

To clarify, the annual risk is not increasing in your example. The cumulative risk over "N-years" is increasing.

Michele

 

[Eva]

You will find several threads on this subject on this forum. I have never had a cardio or PCP mention this kind of "cumulative" risk. Maybe they have tried to "protect me' since I've been on coumadin/warfarin for over 42 years. It makes sense that, with age and other health problems, the risk of a "bleeding event" will increase, but not in a cumulative way. If such a statement could be true, why in hell would any younger person (under 60) put himself, or herself, at such a high potential risk by choosing a mechanical valve. I would suggest that your cardio "put his mind in gear before he puts his mouth in motion" Incidently, your guy is consertative, some have posted that their doc says 2% to 5% on a cumulative basis.

I totally agree.

 

[ALCapshaw2]

Al, thank you for a very informative and helpful post. I hate to nitpick, but there is one word off in your summary, or perhaps I misunderstood.



To clarify, the annual risk is not increasing in your example. The cumulative risk over "N-years" is increasing.

Michele

You are right Michel. I was in a hurry and tried to over-simplify which resulted in an erroneous and confusing statement. I will delete that statement from my previous post.

I think the analogy to having had an auto accident over N years is valid IF the assumption of a fixed / constant annual risk is valid. The calculation is the same as outlined by Bradley White (1-Risk)^N .... which doesn't mean much to those not familiar with mathematical symbols and terminology.

'AL Capshaw'

 

[olefin]

Fully agree with Dick and his record speaks out loud!

Myself, I've never heard of "cumulative risk".

Sounds like something from doctors that are frighten of warfarin.

I had a severe bleeding duodenal ulcer the year 'before' surgery. Guess my doctors hadn't heard of cumulative risk.