AMC MCQ - Australian Medical Council Multiple Choice Questions Population Health and Epidemiology Questions and Answers 1 — Questions and Answers
Question 1: Researchers wish to investigate a potential link between a rare form of liver cancer and exposure to a specific industrial solvent. They identify 100 individuals with this cancer from a national registry and select 200 individuals without the cancer from the general population. A detailed occupational history is then taken from all participants to determine past exposure to the solvent. Which of the following best describes this study design?
- Randomised controlled trial
- Cohort study
- Case-control study (Correct answer)
- Cross-sectional study
Correct answer: Case-control study
This is a case-control study. The design starts by identifying participants based on their disease status (cases with liver cancer vs. controls without) and then looks backward in time (retrospectively) to compare the frequency of exposure to the solvent in each group. This design is particularly efficient for studying rare diseases.
Question 2: A public health program offers free influenza vaccinations to all healthcare workers before the flu season begins. This initiative aims to prevent the workers from contracting influenza and spreading it to vulnerable patients. Which level of prevention does this activity represent?
- Tertiary prevention
- Primary prevention (Correct answer)
- Secondary prevention
- Primordial prevention
Correct answer: Primary prevention
This is an example of primary prevention. Primary prevention aims to prevent the onset of disease before it occurs. Vaccination provides immunity to prevent the initial infection, thus stopping the disease process from starting.
Question 3: In a hospital-based case-control study investigating risk factors for acute pancreatitis, cases are patients admitted with the condition. The investigators select controls from the orthopaedic ward, consisting of patients admitted for elective knee replacement surgery. The study finds a strong association between high alcohol consumption and pancreatitis. Which type of bias is the most significant concern for the validity of these findings?
- Recall bias
- Observer bias
- Confounding
- Selection bias (Correct answer)
Correct answer: Selection bias
Selection bias is the most significant concern. The control group (elective knee replacement patients) is not representative of the general population from which the cases arose. This group may have different baseline characteristics, including different rates of alcohol consumption or other health behaviours, compared to the source population of the cases. This systematic difference in the selection of study groups can distort the true association between alcohol and pancreatitis.
Question 4: According to the Wilson and Jungner criteria, which of the following is an essential principle for a successful and ethical population-based screening program?
- The screening test must have 100% sensitivity.
- There should be an accepted and available treatment for the condition if detected. (Correct answer)
- The condition must have a very high prevalence in the population.
- The natural history of the condition does not need to be well understood.
Correct answer: There should be an accepted and available treatment for the condition if detected.
A core principle of screening is that there must be an effective and accessible treatment for individuals diagnosed with the condition. Screening for a disease for which no effective treatment exists would provide little benefit to the individual or the population and could cause unnecessary anxiety and harm.
Question 5: In a stable population of 50,000 people, there were 1,000 existing cases of diagnosed osteoarthritis at the start of a year. Over the course of that year, 200 new cases were diagnosed. What was the incidence rate of osteoarthritis per 1,000 people for that year?
- 4.1 (Correct answer)
- 4.0
- 24.0
- 5.0
Correct answer: 4.1
Incidence measures the rate of new cases in the population at risk. The population at risk is the total population minus those who already have the disease (50,000 - 1,000 = 49,000). The calculation is (Number of new cases / Population at risk) * 1000. Therefore, (200 / 49,000) * 1000 ≈ 4.08, which is approximately 4.1 per 1,000 people.
Question 6: Which measure of association is most appropriately calculated in a cohort study to compare the incidence of disease in an exposed group to the incidence in an unexposed group?
- Odds Ratio (OR)
- Prevalence Rate
- Attributable Risk
- Relative Risk (RR) (Correct answer)
Correct answer: Relative Risk (RR)
Relative Risk (RR), also known as the risk ratio, is the appropriate measure for a cohort study. It directly compares the risk (incidence) of developing a disease in the exposed group to the risk in the unexposed group (Incidence in exposed / Incidence in unexposed). Case-control studies, in contrast, typically calculate the Odds Ratio (OR) as an estimate of the RR.
AMC MCQ - Australian Medical Council Multiple Choice Questions Population Health and Epidemiology Questions and Answers 1
Researchers wish to investigate a potential link between a rare form of liver cancer and exposure to a specific industrial solvent.
They identify 100 individuals with this cancer from a national registry and select 200 individuals without the cancer from the general population.
A detailed occupational history is then taken from all participants to determine past exposure to the solvent.
Which of the following best describes this study design?