Critical appraisal Flashcards
Confounder
variable associated with both exposure and outcome
Best type of study design to minimize effects of confounders
RCT
Cons of doing RCT
Expensive, time consuming, difficult for rare events
how to calculate relative risk
incidence of intervention / incidence of control
Relative risk reduction
ARR = (risk in intervention - risk in control)
divided by
risk in control group
(or 1-RR)
case control studies
identify groups based on a specific OUTCOME, see if they have certain exposures
cohort studies
follow subjects with a specific EXPOSURE and evaluate outcomes, exposure not under investigator’s control
best method to study rare diseases
case control (go back and look at their history)
sensitivity
given that the disease is present, the probability that the test is positive
specificity
given that the disease is absent, the probability that the test is negative
sensitivity (equation)
TP/(TP+FN)
specificity (equation)
TN/(TN+FP)
positive predictive value
given that the test is positive, the probability that the disease is present
negative predictive value
given that the test is negative, the probability that the disease is absent
PPV and NPV vary with…
disease prevalence
