BCSE Preventive Medicine and Public Health 2 — Questions and Answers
Question 1: Which measure best describes the probability that a person with a positive screening test truly has the disease?
- Sensitivity
- Specificity
- Positive predictive value (Correct answer)
- Negative predictive value
Correct answer: Positive predictive value
Positive predictive value (PPV) is the proportion of true positives among all positive test results.
Question 2: The epidemiological transition refers to:
- A shift from infectious to chronic diseases as leading causes of death (Correct answer)
- The movement of disease vectors across geographic borders
- Increased antibiotic resistance in developing nations
- Migration patterns affecting disease distribution
Correct answer: A shift from infectious to chronic diseases as leading causes of death
The epidemiological transition describes the historical shift from infectious/parasitic diseases to non-communicable chronic diseases as populations develop.
Question 3: A study finds a relative risk of 0.4 for coronary heart disease among regular exercisers versus sedentary individuals. The attributable risk percent in the exposed group is:
- 40%
- 60% (Correct answer)
- 140%
- 0.4%
Correct answer: 60%
Attributable risk percent = (RR - 1) / RR × 100 = (0.4 - 1) / 0.4 × 100; since RR < 1, it represents a 60% reduction in risk.
Question 4: Which level of prevention does administering HPV vaccine to adolescents represent?
- Primordial prevention
- Primary prevention (Correct answer)
- Secondary prevention
- Tertiary prevention
Correct answer: Primary prevention
HPV vaccination prevents initial infection and subsequent cancer, making it primary prevention by reducing disease incidence.
Question 5: The 'sick building syndrome' is most commonly attributed to:
- Radon gas accumulation
- Poor indoor air quality and inadequate ventilation (Correct answer)
- Lead paint exposure
- Legionella contamination of water systems
Correct answer: Poor indoor air quality and inadequate ventilation
Sick building syndrome symptoms are linked to time spent in a building with poor ventilation, chemical off-gassing, and biological contaminants.
Question 6: Which statistical test is most appropriate for comparing means across three or more independent groups?
- Chi-square test
- Paired t-test
- One-way ANOVA (Correct answer)
- McNemar's test
Correct answer: One-way ANOVA
One-way ANOVA tests whether there are statistically significant differences between the means of three or more independent groups.
Question 7: Herd immunity threshold is best calculated as:
- 1 - (1/R0) (Correct answer)
- R0 / (R0 - 1)
- 1 / R0
- (R0 - 1) / R0
Correct answer: 1 - (1/R0)
The herd immunity threshold = 1 - (1/R0), where R0 is the basic reproduction number.
BCSE Preventive Medicine and Public Health 2
Which measure best describes the probability that a person with a positive screening test truly has the disease?