B3.044 - Evidence Based Medicine: Evaluating New Drugs Flashcards
heparin and warfarin are both used for what
to treat venous thrombi
which drug is used first for venous thrombi
heparin
warfarin is used to prevent blood clots in patients with what
atrial fribrillation
what is the goal of warfarin
prolonged PT
when is the therapeutic goal of warfarin achieved
about 1 week
which drug has a slow onset
warfarin
what is the INR
the international normalized ratio of test/control
why is warfarin dose selection so difficult
narrow therapeutic index
multiple factors affect pharmacokinetics and pharmacodynamics
what are the big dietary things that affect warfarin function
alcohol and leafy greens
why is an alternative to warfarin something we want
bad side effects and interactions
what is alpha
probability of a false positive
what is beta
probability of a false negative
what is beta usually
.2
what is alpha usually
.05
what is a type 1 error
rejecting null when you shouldnt have
what is a type 2 error
not rejecting null when you should have
how is power calculated
1-beta
steps to calculating sample size (4)
- determine study size, measure of frequency, measure of effect, stat method
- set acceptable levels of risk of a type 1 and type 2
- determine magnitude of diff in outcomes between 2 groups
- calculate sample size requirement
larger differences require what to be detected
smaller sample sizes to be detected
reduced risk of type 1 error results in
larger sample size requirement
reduced power results in
smaller sample size requirement
