Chapter 5: Principles of Epidemiology Flashcards
Epidemiology
From the Greek word meaning “upon the people”; the study of epidemics; the basic science of public health; “the study of the distribution and determinants of health-related states in specified populations, and the application of this study to control health problems.”
Vital Statistics
Figures pertaining to life events, such as births, deaths, and marriages.
Case
A particular instance of a disease or outcome of interest.
Risk
The probability or likelihood of an event occurring– in this case, the probability that people will acquire a disease.
Risk Factors
Clinically important signs associated with an increased likelihood of acquiring a disease.
Incidence
The number of new cases of a disease during a specific time period in a defined population.
Prevalence
The number of existing cases of a disease or other condition in a given population.
Point Prevalence
The amount of a particular disease present in a population at a particular point in time; usually the time a survey was done.
Period Prevalence
The amount of a particular disease in a population over a period of time.
Prevalence Rate
The proportion (usually the percentage) of persons in a population who have a particular disease or attribute at a particular point in time.
Endemic
A disease that occurs regularly in a population as a matter of course.
Epidemic
An unexpectedly large number of cases of an illness, specific health-related behavior, or other health-related event in a particular population.
Pandemic
An outbreak of disease over a wide geographical area such as a continent.
Cohort
A well-defined group of people who are studied over a period of time to determine their incidence of disease, injury, or death.
Validity
Measures what it says it was going to measure; accurate.
Reliability
Consistent in it’s measurements.
Ecological Study
Focuses on groups of people (rather than individuals) and examines the relationship between exposure and disease with the population-level rather than individual-level data. Can be used as the first step in exploring the relationship between an exposure and a disease. Cannot be used to show cause and effect, but generates a theory. Can compare two populations.
Cross-Sectional Study
A study where exposure factors (e.g., individual or environmental risk factor, nutrition education) and outcomes (e.g., disease occurrence, eating behavior) are observed or measured at one point in time in a sample from the population of interest, usually by survey or interview. In this design, a researcher examines the association among factors and outcomes using a statistical test for association, but cannot infer cause and effect. A snapshot.
Cohort Study
A type of observational analytic study that can be retrospective or prospective in nature. Enrollment in the study is based on exposure characteristics or on membership in a group. Disease, death, and/or other health-related outcomes are then determined and compared. Comparison groups can be defined at the beginning or created later using data from the study.
Prospective Cohort Study
Studies enroll individuals and then collect data at many intervals. Look into the future.
Retrospective Cohort Study
Studies use an existing longitudinal data set to look back for a temporal relationship between exposure factors and outcome development. Look into the past.
Case-Control Study
A type of observational study; involves identifying patients who have the outcome of interest (cases) and matching them with individuals who have similar characteristics, but do not have the outcome of interest (controls). Characteristics, such as previous exposure to a factor (i.e., the hypothesized casual or contributing factors), are then compared between cases and controls.
Experimental (Controlled) Trial
Examines preventions and treatments for diseases; investigator actively manipulates which groups receive the agent under study. Can be blind, double blind, controlled and randomized. Most rigorous.
