Match the following diagnostic and screening test performance characteristics with their appropriate clinical interpretations.
- SensitivityOf all the patients in the population who truly have the disease, what proportion will be identified by a positive test?
- SpecificityOf all the patients in the population who are disease-free, what proportion will be correctly identified by a negative test?
- Positive Predictive Value (PPV)If a patient in the clinic tests positive, what is the probability they actually have the disease?
- Negative Predictive Value (NPV)If a patient in the clinic tests negative, what is the probability they are truly disease-free?
Answer
Sensitivity pairs with identifying diseased patients. Specificity pairs with correctly identifying disease-free patients. PPV pairs with the probability of disease given a positive test. NPV pairs with the probability of being disease-free given a negative test.
Matching these definitions correctly relies on understanding the direction of inquiry. Sensitivity and Specificity start with the true disease status (columns of a 2x2 table) and ask about the test result, serving as intrinsic properties of the test. PPV and NPV start with the test result (rows of a 2x2 table) and ask about the true disease status, serving as clinically relevant post-test probabilities.
Step-by-Step Solution
Key Concept
Fundamental definitions of diagnostic test characteristics (Sensitivity, Specificity, PPV, NPV)