Public Health, Epidemiology and Health Legislation
Core concepts
This domain combines epidemiologic measures, study design, screening principles, and Albanian health law. Know incidence vs prevalence (incidence = new cases over time; prevalence = all cases at a point), relative risk vs odds ratio (cohort vs case-control), and the interpretation of sensitivity, specificity, positive predictive value, and negative predictive value. Understand bias types (selection, information, confounding), the levels of prevention (primary, secondary, tertiary), and outbreak investigation steps. For legislation, focus on patient rights, informed consent, confidentiality, mandatory reporting, and the organization of the health system and primary care.
Common traps
PPV and NPV depend on prevalence - a common trap is assuming a highly sensitive test always gives a high PPV in a low-prevalence population. Distinguish relative risk (used in cohort studies) from odds ratio (case-control). Confusing incidence with prevalence is frequent. In legal questions, distinguish capacity from competence and remember that consent must be informed, voluntary, and given by a capable patient; minors and incapacitated patients require surrogate consent except in emergencies.
Worked example
A screening test with 90% sensitivity and 95% specificity applied in a population with 1% prevalence yields a low PPV. Rule of thumb: when prevalence is low, most positive results are false positives, so confirmatory testing is essential.
Rule of thumb
Always ask what the question is measuring: occurrence (incidence/prevalence), association (RR/OR), or test performance (sens/spec/PPV/NPV).