Usmle 1 Behavioral Science

Front 1

case-control studies
def?
2 types: retrospective and observational

Back 1

def: comparing people with a disease to people without it
retrospective: look at people with a disease to see if they had a given risk factor
observational: follow people with a risk factor and see if they get a disease

Front 2

true positive

Back 2

person has disease and test is positive for it

Front 3

true negative

Back 3

person does NOT have disease and test is negative for it

Front 4

false positive

Back 4

person does NOT have disease and test is positive

Front 5

false negative

Back 5

person has disease but test is negative

Front 6

sensitivity
def?
equation?
use?
if value near 1?

Back 6

def: proportion of all people with the disease who test positive or the ability for a test to detect a disease when it is present
eqn: TP / (TP + FN) or 1- false negative rate
use: screening for disease with low prevalence (e.g. D-dimer for PE)
if value near one you can rule out dz
SNOUT- SeNsitivity rules OUT dz

Front 7

Specificity
def?
equation?
use?
if value near 1?

Back 7

proportion of all people without disease who test negative- the ability of a positive test to diagnose dz
eqn: TN / (TN + FP)
use: confirmatory test after positive screening test
SPIN- if high Specificity test is Positive it rules IN the disease

Front 8

Positive Predictive Value (PPV)
def?
equation?
affect of prevalence?

Back 8

probability that a positive test result is a true positive (given positive test person actually has disease)
prevalence: if prevalence is high then positive test is more likely to be positive

Front 9

Negative Predictive Value (NPV)
def?
equation?
affect of prevalence?

Back 9

probability that a negative test result is a true negative (given negative test person actually does NOT have disease)
eqn: TN / (TN + FN)
prevalence: if prevalence is low then a negative test is more likely to actually be neg