Community Medicine Cheat Sheet
Epidemiology Makes Patterns Actionable
Epidemiology basics: definition, person-place-time, John Snow, incidence versus prevalence, cohort and case-control studies and surveillance for NEET-PG.
MedNext Academy | 3 min read
Epidemiology Makes Patterns Actionable
Epidemiology basics: definition, person-place-time, John Snow, incidence versus prevalence, cohort and case-control studies and surveillance for NEET-PG.
Epidemiology is the study of the distribution and determinants of health-related states in specified populations and the application of that study to disease control, using person, place and time description before causal analysis.
High-yield lines
- Epidemiology studies distribution and determinants of health-related states in specified populations and applies findings to control health problems.
- The four pillars are frequency, distribution, determinants and application to control.
- Distribution is described by person, place and time, known as the epidemiological triad of descriptive epidemiology.
- Epidemiology always requires a specified population with a denominator, unlike clinical medicine which studies individuals.
- John Snow's 1854 investigation of the Broad Street pump stopped a cholera outbreak without knowledge of the causative bacterium.
- India certified elimination of wild poliovirus in 2014 after the Pulse Polio campaign launched in 1995.
- India recorded its last smallpox case in 1975 before global eradication was certified.
- Incidence measures new cases over a time period while prevalence measures existing cases at a point or period.
- Descriptive epidemiology generates hypotheses that analytical studies then test.
- Case-control studies compare exposure in cases and controls and yield the odds ratio.
- Cohort studies follow exposed and unexposed groups forward and yield incidence and relative risk.
- Surveillance is continuous monitoring of disease occurrence against expected levels to detect outbreaks early.
- Community diagnosis identifies the burden, pattern and priority health problems of a defined population.
- Every epidemiological finding should ultimately serve prevention, treatment, surveillance or policy.
Mapped competency codes
- CM7.1
- CM7.2
- CM7.3
- CM7.4
- CM7.5
- CM7.6
- CM7.7
- CM7.8
- CM7.9
Continue into the full chapter
This summary maps to CM7-epidemiology.
Frequently Asked Questions
What is the standard definition of epidemiology?
The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.
What are the components of descriptive epidemiology?
Person, place and time, describing who is affected, where clustering occurs and when the peak happens before determinants are analysed.
Why is John Snow's cholera study a landmark?
By mapping cases, comparing water supplies and removing the Broad Street pump handle, he controlled an outbreak without knowing the causative organism, defining the epidemiological method.
How do cohort and case-control studies differ in output?
Cohort studies follow exposed and unexposed groups forward and give incidence and relative risk, while case-control studies look back at exposure and give the odds ratio.
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