cpp key facts Flashcards
(22 cards)
what is the triangle of evidence
bottom- editorials, expert opinions
case series case studies
cross sectional
case control
cohort studies
randomised controlled trials-
systematic reviews top
what is the other version of the triangle of evidence
expert opinions, editorials- bottom
case series, case studies
observational studies
non randomised controlled trials
randomised control trials
systematic reviews
in the context of sensitivities, specifities, what are the following labels representative of
a b c d
a- true positives
b- false positives
c- false negatives
d- true negatives
what is the definition of sensitivity
the probability that someone who has the condition will test positive for it
what is the formula for sensitivity
a/a+c x 100
true positives/ true positives+ false negative
what is the definition of specificity
the probability that the people who do not have the condition will test negative for it
what is the formula for specificity
d/b+d x 100
what is the definition of positive predictive value
of those who test positive, what proportion actually have the disease
what is the formula of positive predictive value
a/a+b x 100
what is the definition of the negative predictive value
out of people who tested negative, what proportion actually dont have the disease
what is the formula for negative predictive value
d/d+c x100
what is the definition of prevalence
proportion of the population who truly have the disease- cross sectional study
what is the formula for prevalence
a+c/N
a- true positive-have the disease
c-false negative- have the disease
N- number of people in the population
what affect does increasing prevalence have on the positive predictive value
increases ppv
what affect does increasing prevalence have on the negative predictive value
decreases npv
how are odds (case control studies) calculated
number of people with disease/number of people without disease
what is the formula for risk
number of people experiencing event in a defined period/ number of people in study population at start of period
define person years at risk
sum of number of years people with risk of the event have been followed
what is the formula for rate
number of people experiencing event in defined period/ person years at risk
what is definition of rate
measure of the rate at which an event (new case or disease) occurs in a population over a period of time (units per person year)
what are kaplan meier plots
graph of probability of having the disease by time of follow up drawn as a series of steps which only change at time of event
