Practice questions › Davidson's Principles of Medicine › Davidson's Medicine - Part 1: Fundamentals of Medicine
Davidson's Medicine - Part 1: Fundamentals of Medicine, Part 1 - Fundamentals of Medicine (overview) MCQs
Davidson's Medicine - Part 1: Fundamentals of Medicine · Davidson's Principles of Medicine · 27 practice questions
- Root causes of diagnostic error
- Root causes of diagnostic error - categorisation
- Normal values and reference ranges
- Evidence-based history and examination
- Likelihood ratios and diagnostic weight
- Diagnostic test result interpretation in disease populations
- Diagnostic test interpretation factors
- History and physical examination in diagnosis
1. A clinician is taught that likelihood ratios (LRs) reflect how much a single clinical finding changes the probability of disease. In a patient with a high overall clinical probability of meningitis based on history, the finding of neck stiffness (LR ~1) is obtained on examination. What is the most accurate interpretation of this finding?
- AIt substantially decreases the probability that the patient has meningitis
- BIt cannot be interpreted because LRs only apply when the diagnostic standard test has already been performed
- CIt has little effect on the probability of disease, which remains determined mainly by the pre-test probability
- DIt substantially increases the probability that the patient has meningitis
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C. It has little effect on the probability of disease, which remains determined mainly by the pre-test probability The text states that an LR of around 1 means the finding is of little use in changing the probability of disease, and that if the overall clinical probability is high to begin with, a finding with an LR around 1 does not change this.
2. A hospital review of a missed diagnosis finds that the on-call registrar was left to manage a complex overnight admission without any senior consultant available for advice, and this contributed to an incorrect diagnosis being made. According to the classification of root causes of diagnostic error, which category does this best fall under?
- AHuman cognitive error due to a knowledge gap
- BHuman cognitive error due to misinterpretation of a diagnostic test
- CSystem error
- DNo fault error
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C. System error Poor supervision of inexperienced staff is listed as an example of a 'system error' (error-prone process), distinct from no-fault error and human cognitive error categories.
3. Two medical students are being taught about meningitis presentations. Student A memorises a list of classic features (headache, fever, meningism). Student B is taught the actual prevalence of each feature and its diagnostic weight in real patient populations, along with the underlying basic science. According to research described in the text, which student is likely to have better diagnostic accuracy, and why?
- AStudent A, because memorising classic feature lists is proven to be more reliable in clinical practice
- BBoth will have equal accuracy since diagnostic accuracy depends only on experience, not teaching method
- CStudent A, because textbook lists always reflect the true prevalence of clinical findings
- DStudent B, because understanding probabilities of features and basic science explanations improves diagnostic accuracy
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D. Student B, because understanding probabilities of features and basic science explanations improves diagnostic accuracy The text states that students taught the probabilities of features being present in specific diseases (rather than lists of features) have better diagnostic accuracy, further improved by understanding basic science explanations.
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