Key Terms for Exam 2 Flashcards
agent
causative factor invading a susceptible host through an environment favorable to produce disease, such as a biological or chemical agent.
analytic epidemiology
a form of epidemiology that investigates causes and associations between factors or events and health.
attack rate
a type of incidence rate defined as the proportion of persons who are exposed to an agent and who develop the disease, usually for a limited time in a specific population.
bias
in determining causality, a systematic error because of the way the study is designed, how it was carried out, or some unplanned events that occurred and affected the study.
case-control study
an epidemiologic study design in which subjects with a specified disease or condition (cases) and a comparable group without the condition (controls) are enrolled and assessed for the presence or history of an exposure or characteristic.
case fatality rate
the proportion of persons diagnosed with a specific disorder who die within a specified time.
causal inference
using epidemiologic, clinical, statistical, and other scientific evidence to judge if a causal association exists between two or more factors or events. Guidelines for evaluation of evidence are often used in making causal inference. Different levels of evidence may be required for different settings, for example, clinical decisions versus policy determinations.
cohort study
an epidemiologic study design in which subjects without an outcome of interest are classified according to past or present (or future) exposures or characteristics and followed over time to observe and compare the rates of some health outcome in the various exposure groups.
confounding
a bias that results from the relationship between both the outcome and study factor (exposure or characteristic) and some third factor not accounted for in analysis.
cross-sectional study
an epidemiologic study in which health outcomes and exposures or characteristics of interest are simultaneously ascertained and examined for an association in a population or sample, providing a picture of existing levels of all factors.
descriptive epidemiology
a form of epidemiology that describes a disease according to dimensions of person, place, and time.
determinants
factors that influence the risk for or distribution of health outcomes.
An influencing or determining element or factor
distribution
a pattern of a health outcome in a population; the frequencies of the outcome according to various personal characteristics, geographic regions, and time.
ecological model
a multidimensional model of determinants of health and disease that spans many levels from individual genetic and physiologic characteristics to broader contextual influences (e.g., neighborhood characteristics and social context). This model encompasses a broader spectrum of systems and etiologic factors than the web of causality model and includes a lifespan perspective.
environment
for public health refers to all factors that constitute the context in which persons or animals live and that influence and are influenced by the host and agent–host interactions.
epidemic
a rate of disease clearly in excess of the usual or expected frequency in that population.
epidemiology
the study of the distribution and factors that determine health-related states or events in a population and the use of this information to control health problems.
host
a human or animal that provides adequate living conditions for any given infectious agent.
incidence proportion
the proportion of the population at risk who experience the event over some period of time.
incidence rate
the frequency or rate of new cases of an outcome in a population; it provides an estimate of the risk of disease in that population over the period of observation.
levels of prevention
a three-level model of interventions based on the stages of disease, designed to halt or reverse the process of pathological change as early as possible, thereby preventing damage.
natural history of disease
the course or progression of a disease process from onset to resolution.
negative predictive value
the proportion of persons with a negative test who are disease free.
point epidemic
a concentration in space and time of a disease event, such that a graph of the frequency of cases over time shows a sharp point, usually suggestive of a common exposure.
positive predictive value
the proportion of persons with a positive screening or diagnostic test who do have the disease (the proportion of “true positives” among all who test positive).
prevalence proportion
a measure of existing disease in a population at a given time.
primary prevention
a type of intervention that seeks to promote health and prevent disease from the beginning.
proportion
a type of ratio in which the denominator includes the numerator.
proportionate mortality ratio
the proportion of all deaths due to a specific cause.
rate
a measure of the frequency of a health event in a defined population during a specified period.
reliability
the precision, stability, agreement, or replicability of a measuring instrument when repeatedly used; an indication of consistency from time to time or from person to person.
risk
the probability of some event or outcome occurring within a specified period.
screening
the application of a test to people who are as yet asymptomatic for the purpose of classifying them with respect to their likelihood of developing a particular disease.
secondary prevention
an intervention that seeks to detect disease early in its progression (early pathogenesis) before clinical signs and symptoms become apparent in order to make an early diagnosis and begin treatment.
secular trends
long-term patterns of morbidity or mortality (i.e., over years or decades).
sensitivity
the extent to which a test identifies those individuals who have the condition being examined.
specificity
the extent to which a test identifies those individuals who do not have the disease or condition being examined.
surveillance
systematic and ongoing observation and collection of data concerning disease occurrence in order to describe phenomena and detect changes in frequency or distribution.
tertiary prevention
intervention that begins once the disease is obvious; the aim is to interrupt the course of the disease, reduce the amount of disability that might occur, and begin rehabilitation.
validity
the accuracy of a test or measurement; how closely it measures what it claims to measure. In a screening test, validity is assessed in terms of the probability of correctly classifying an individual with regard to the disease or outcome of interest, usually in terms of sensitivity and specificity.
web of causality
complex interrelations of factors interacting with each other to influence the risk for or distribution of health outcomes.
