Epidemiology
Epidemiology studies the distribution and determinants of health events in populations and applies this knowledge to prevention, clinical decision making and public-health action.
General subject summary is free to everyone.
Epidemiology
Subject Summary
The public overview below follows the supplied PhysioVeda Academics subject summary.
Epidemiology studies the distribution and determinants of health events in populations and applies this knowledge to prevention, clinical decision making and public-health action.
Core measures include incidence, prevalence, mortality, risk ratios, odds ratios and risk differences; interpretation requires clearly defined populations, time periods and denominators.
Study designs differ in how participants are selected and when exposure and outcome are measured, which affects what measures can be estimated and which biases are most important.
Causal interpretation requires attention to bias, confounding, effect modification, temporality and the total body of evidence rather than statistical association alone.
This summary follows the uploaded PhysioVeda Academics outline from disease-frequency and mortality measures through study designs, bias, screening, surveillance, outbreaks, clinical epidemiology, data quality and ethics.
Whole-subject high-yield numbers
Use these supplied values and key facts for quick whole-subject revision.
| Prevalence | Existing cases / population |
| Cumulative incidence | New cases / population initially at risk over a period |
| Incidence rate | New cases / person-time |
| Risk ratio | Risk exposed / risk unexposed |
| Odds ratio | Odds exposed / odds unexposed or exposure odds among cases vs controls |
| Risk difference | Risk exposed - risk unexposed |
| Sensitivity | TP/(TP+FN) |
| Specificity | TN/(TN+FP) |
| Attack rate | Cumulative incidence during an outbreak |
| R0 concept | Average secondary cases generated in fully susceptible population under specified conditions |
Core references
- Gordis L. Gordis Epidemiology. 6th ed. Elsevier; 2019.
- Rothman KJ, Greenland S, Lash TL. Modern Epidemiology. 4th ed. Wolters Kluwer; 2021.
- Celentano DD, Szklo M. Gordis Epidemiology. 7th ed. Elsevier; 2024.
- Friis RH, Sellers TA. Epidemiology for Public Health Practice. 6th ed. Jones & Bartlett Learning; 2020.
Want to go deeper into Epidemiology?
Continue into the complete topic and subtopic learning system with structured summaries, medical visuals, topic wise OBQ practice, timed tests, explanations and results.