Chapter 7: Evidence-Based Decision Making and Diagnostic Testing
This chapter explores how clinicians use elements of the history, physical
examination, and diagnostic tests to inform clinical decisions. It emphasizes
evaluating and applying clinical evidence, understanding key statistical
concepts, and communicating findings effectively to patients.
Using Elements of the History and Physical Examination as
Diagnostic Tools
1. Diagnostic Value:
oHistory and physical examination findings often act as "tests."
oExample: The presence of chest pain radiating to the arm in a
55-year-old smoker increases the likelihood of myocardial
infarction (heart attack).
2. Pre-Test Probability:
oThe likelihood a patient has a condition before additional tests.
oClinicians use population data, risk factors, and symptoms to
estimate this.
Evaluating Diagnostic Tests
1. Sensitivity and Specificity:
oSensitivity: The ability of a test to correctly identify those with
the disease (true positives).
Example: A highly sensitive COVID-19 test identifies most
infected individuals but may have some false positives.
Mnemonic: SeNsitive = rule iN (SnNout) for disease
screening.
oSpecificity: The ability to correctly identify those without the
disease (true negatives).
Example: A specific strep throat test ensures false positives
are minimal.
Mnemonic: SPecific = rule out (SpPin) when positive.
