Evidence -Based Approaches to Public Health: Concepts of Epidemiology Flashcards
Ratio
Dividing one number by another, but the numerator does NOT need to be a subset of the denominator. 2 different quantities
Proportion
Dividing one number by another, but the numerator DOES need to be a subset of the denominator
Rate
Dividing one number by another but adding a time component in the denominator
Incidence
Measure of the number of new cases of a disease
Cumulative Incidence
Number of new cases of a disease in a period of time
Incidence Rate
Number of new cases of the disease during person-time of observation
Prevalence
Number of existing cases of a disease during a given time period. May include new cases as well
Point Prevalence
The proportion of the population that is diseased at a single point in time
Period Prevalence
The proportion of the population that is diseased during a specific duration of time
Endemic
A situation in a community in which there is a consistent elevated rate of a certain disease
Epidemic
An increase in the number of cases in a community, above what is expected
Pandemic
Worldwide epidemic
Descriptive Studies
Generally observational (no hypothesis testing)
- case reports
- case series
- cross-sectional
Analytical Studies
Interventional (experimental) and observational (hypothesis testing)
- Experimental
- RCT
- Non-Randomized Control Trial
- Observational
- Cohort
- Case-Control
- Cross-Sectional
Case Studies/Case Reports
Studies are used to alert people of a new illness or new association with illness. Reports of only people with the condition of interest.
Cross-Sectional Studies
Studies that include people who are representative of a given population. Not selected based on illness or exposure and can be used to determine initial association and identify the prevalence of either exposure or illness in a group.
Ecological Studies
Studies that are used to describe populations. Not analyzed on an individual level.
Ecological Fallacy
Group level data are used to report on individuals
Case-Control Studies
Studies select people with or without disease and then proceed to look back over time to see if people had different rates of exposure. Good for rare diseases with long latency periods
Latency Period
Diseases that take a long time to develop
Cohort Studies
Studies that selected people on the basis of exposure and determine if people develop the disease at different rates. Good for rare exposures and may follow individuals into prospective or retrospective. Incidence can be calculated from this type of study. Prevalence cases are excluded
Prospective
Into the future
Retrospective
Looking back in time
Prevalence Cases
People who have the disease at the time point when the study period begins
Randomized Control Trial (RCT)
Tests an intervention that is given by the researcher by 2 or more groups. People are randomly assigned into groups through randomization with one given the active item and the other group the usual treatment or a placebo. The researcher follows them over time and compares outcomes. Participants do not know which group they are in.
Systematic Review and Meta-Analyses
Pool the results of multiple independent studies with established criteria to identify the evidence for associations
Relative Risk
Measure of the magnitude of an association between an exposure and a disease that is used in cohort studies. Ratio of the risk (incidence) of disease exposed to the risk in the nonexposed
Odds Ratio
Calculated in case-control studies or cross-sectional studies. Odds of exposure among cases divided by odds of exposure among controls, which equals the odds of disease among the exposed divided by the odds of disease among the nonexposed.