Practice questions › Davidson's Principles of Medicine › Davidson's Medicine - Part 1: Fundamentals of Medicine
01 Clinical decision-making MCQs
Davidson's Medicine - Part 1: Fundamentals of Medicine · Davidson's Principles of Medicine · 15 practice questions
- Cognitive biases
- Problem representation
- Sensitivity and specificity
- Diagnostic tests
- Team communication
- Likelihood ratios
- Dual process theory
- Predictive value
1. A very sensitive test (95%) is negative in a patient whose pre-test probability of disease is high. Which statement is correct?
- ADisease is unlikely to be excluded by this alone, since the test misses 1 in 20 affected patients and clinical probability must be weighed
- BDisease is reliably excluded because sensitivity is 95%
- CThe negative predictive value is 95% in any population
- DDisease is excluded regardless of pre-test probability
Show answer
A. Disease is unlikely to be excluded by this alone, since the test misses 1 in 20 affected patients and clinical probability must be weighed Predictive value depends on prevalence and pre-test probability; even a good test misses 1 in 20, and the negative result in a high-probability patient does not exclude disease.
2. A test for a disease of prevalence 1 in 1000 has a 5% false-positive rate and no false negatives. An asymptomatic person tests positive. What is the approximate chance of disease?
- AAbout 50%
- BAbout 95%
- CAbout 2%
- DAbout 5%
Show answer
C. About 2% Per 1000 people, 1 true positive and about 50 false positives, so roughly 1 in 51 (about 2%).
3. A doctor summarises a case as 'a 30-year-old pregnant woman with acute left pleuritic chest pain and breathlessness' before ordering tests. What is the main advantage?
- AIt guarantees a correct diagnosis
- BIt removes the effect of biases
- CIt retrieves relevant knowledge from long-term memory and guides an action plan while a diagnosis is unavailable
- DIt replaces the need for a differential
Show answer
C. It retrieves relevant knowledge from long-term memory and guides an action plan while a diagnosis is unavailable Problem representation in precise language improves accuracy in complex cases and helps organise knowledge.
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