Medical Testing

Question 1

Screening tests
-sensitivity vs specificity

Answer 1

Sensitivity - patients with condition with a positive result/all patients with condition

Specificity - patients without condition with a negative result/all patients without condition

Question 2

Screening tests
-positive predictive value vs negative predictive value

Answer 2

PPV - positively and correctly identified/all positively identified

NPV - negative and correctly identified/all negatuvely identified

Question 3

Screening tests
-likelihood ratio for positive test vs likelihood ratio for negative test

Answer 3

Likelihood ratio for positive test result - how odds of disease increase when a test is positive

Sensitivity/1-specificity

Likelihood ratio for negative test result - how odds of disease decrease when a test is negative

1-sensitivity/specificity

Question 4

Incidence vs prevalence

Answer 4

Incidence - number of NEW cases per population in a specific time period

Prevalence - total number of cases in a population at a specific point in time

Point prevalence - number of IDENTIFIED cases in a defined population/ number of people in a defined population at the same time

Period prevalence - number of IDENTIFIED cases in a defined population/number of total people in that population