AMC MCQ Population Health and Epidemiology 3 — Questions and Answers
Question 1: Lead-time bias most commonly causes screening programs to falsely appear to:
- Improve survival time (Correct answer)
- Reduce disease incidence
- Lower test specificity
- Increase mortality
Correct answer: Improve survival time
Earlier detection lengthens the apparent survival from diagnosis without changing the actual time of death.
Question 2: A relative risk of 1.0 with a 95% confidence interval of 0.85 to 1.18 indicates the association is:
- Not statistically significant (Correct answer)
- Strongly protective
- Strongly harmful
- Confounded by age
Correct answer: Not statistically significant
A confidence interval crossing 1.0 means the result is not statistically significant.
Question 3: Which of the following is a notifiable disease that doctors in Australia are legally required to report to public health authorities?
- Tuberculosis (Correct answer)
- Essential hypertension
- Type 2 diabetes
- Osteoarthritis
Correct answer: Tuberculosis
Tuberculosis is a nationally notifiable communicable disease requiring mandatory reporting.
Question 4: The incidence of a disease is 5 new cases per 1000 person-years and the average duration is 4 years. What is the approximate prevalence?
- About 20 per 1000 (Correct answer)
- About 5 per 1000
- About 1.25 per 1000
- About 40 per 1000
Correct answer: About 20 per 1000
Prevalence approximately equals incidence multiplied by duration, giving 5 × 4 = 20 per 1000.
Question 5: Which bias arises when cases recall past exposures more thoroughly than controls in a case-control study?
- Recall bias (Correct answer)
- Lead-time bias
- Selection bias
- Berkson bias
Correct answer: Recall bias
Recall bias occurs because people with disease often remember exposures differently than healthy controls.
Question 6: A vaccine trial reports a relative risk reduction of 80%. If the unvaccinated risk is 10%, what is the absolute risk reduction?
- 8 percentage points (Correct answer)
- 80 percentage points
- 2 percentage points
- 20 percentage points
Correct answer: 8 percentage points
Absolute risk reduction equals relative risk reduction times baseline risk, so 0.80 × 10% = 8%.
Question 7: Which level of disease prevention does cervical cancer screening with Pap testing represent?
- Secondary prevention (Correct answer)
- Primary prevention
- Tertiary prevention
- Quaternary prevention
Correct answer: Secondary prevention
Screening detects disease at an early or pre-clinical stage, which defines secondary prevention.
AMC MCQ Population Health and Epidemiology 3
Lead-time bias most commonly causes screening programs to falsely appear to: