DO Diagnostic Reasoning and Evidence-Based Medicine

Question 1

Bayes' theorem in clinical medicine states that the post-test probability of disease depends on which two factors?

Accepted Answer

Pre-test probability and test likelihood ratio

Answer

Post-test probability integrates the pre-test probability (prevalence/clinical suspicion) with the test's likelihood ratio to determine how much a result changes disease probability.

Question 2

When a test has high specificity, a positive result is most useful for:

Accepted Answer

Ruling IN disease (SpPin)

Answer

A highly specific test has few false positives, so a positive result strongly indicates true disease and is used to rule IN the diagnosis (SpPin mnemonic).

Question 3

A 55-year-old male smoker presents with hemoptysis and a new lung mass on CXR. The pre-test probability for lung cancer is estimated at 60%. The CT-guided biopsy has a sensitivity of 95% and specificity of 99%. A positive biopsy result essentially:

Accepted Answer

Confirms the diagnosis (very high post-test probability)

Answer

With high pre-test probability and a highly specific test showing a positive result, the post-test probability of malignancy approaches near certainty.

Question 4

Which statistical measure describes the strength of association between an exposure and outcome in a case-control study?

Accepted Answer

Odds ratio (OR)

Answer

Case-control studies calculate the odds ratio because they sample based on outcome (case/control), making it impossible to calculate true incidence rates needed for relative risk.

Question 5

Confirmation bias in clinical diagnosis refers to:

Accepted Answer

Seeking information that confirms an initial diagnosis while ignoring contradictory evidence

Answer

Confirmation bias leads physicians to favor data supporting their initial hypothesis and discount findings that suggest an alternative diagnosis.

DO - Doctor of Osteopathy Practice Test

DO - Doctor of Osteopathy Practice Test

DO Diagnostic Reasoning and Evidence-Based Medicine