Public Health, Epidemiology and Health Legislation
Public Health, Epidemiology and Health Legislation tests population measures, study design, outbreak investigation, screening, and statutory duties. The exam expects numbers to be interpreted, not just memorised.
Core rules
- Incidence = new cases per population at risk per time; prevalence = all existing cases at a point or period.
- Relative risk compares incidence in exposed and unexposed; odds ratio is used in case-control studies.
- Screening requires a valid test, acceptable treatment, and evidence that early detection improves outcome.
- Outbreak investigation: define cases, describe by time/place/person, formulate hypotheses, then control.
- Notifiable diseases and death certification are legal duties; confidentiality yields only to specific public-health provisions.
Worked example
In a foodborne outbreak, 60 of 200 people who ate potato salad became ill, versus 10 of 100 who did not. Attack rate exposed = 30%; unexposed = 10%; relative risk = 3.0. The reasoning: exposed persons had three times the illness risk. A case-control design may follow if the population is poorly defined.
Traps
Do not call prevalence a risk; do not infer causation from a single cross-sectional association; do not ignore reporting deadlines; do not confuse lead-time bias with true survival benefit.