#### pellicle

##### Professional Dingbat, Guru and Merkintologist

no, it doesn't work like that. Instead its a year on year thing. Probability is best explored through dice roll and coin flip; where each event is independent of the other events.'m asking because I don't know anything about this subject.

Is the risk of strokestill increasing by 1% every year evenif we use warfarin and monitor inr properly?

If you roll the dice then your next roll may or may not be the same number, but it will be independent of the previous (and not in any way predictive of the next) outcome.

People get confused about this when comparing the probability of cards. Each time you take a card the probability of a Jack of Clubs on the next draw increases as we reduce the pack with each draw from 52, to 51 ... eventually if it doesn't turn up beforehand we can be certain that the last card is the Jack of Clubs.

Stroke risk is like the dice roll.

I won't go into it but using the probability theory is all we have for this. The probability is defined in "that graph" I usually post as (if you are in INR sweet spot range) less than 3 events per 100 patient years.

This can be either if you have 100 years on warfarin or if 100 patients have 1 year.