Characterizing Populations and Diseases in Epidemiology Flashcards
What is an epidemiologic population?
A specific group of people defined by…
person (who is getting the disease?) e.g. age, sex, race/ethnicity, job, SES
place (where is it occurring?)
e.g. geopolitical, natural geographic features, environment
time (how is it changing over time?)
e.g. calendar year, time in the life course, can range from hours to decades
EX: citizens of US during 2020 consensus, participants in the Framingham Heart Study first wave of recruitment (1948)
Why is population important?
Important for formulating hypotheses regarding disease, and understand health status
also for planning, implementation, and evaluating public health programs to control and prevent disease
What is population “at risk”?
Some epidemiologic measures focus on. new cases of a disease. For those measures, the denominator should only consist of people who are “at risk” for the disease. Those who are not at risk include: people who currently have the disease, people who lack the organ defining the disease, and people who are immune to the disease
What is “person-time” at risk?
It is often important to know not only who was at risk, but also how long each person was at risk.
What is a population?
A group of people who share a common characteristic (person, place, time). But every population is heterogenous with regard to other characteristics and so we often specify subgroups of a population and treat each subgroup as being homogenous.
What are two methods we can use when comparing populations?
Inherently, statistics about populations are weighted averages over all of the subgroups making up that population. This becomes especially important when comparing populations. Two methods we can use to do this are using crude rates, and specific rates
Explain crude and specific rates.
Crude rates refer to rates calculated for the entire population of interest (actual number of overall events in popln over a specific period of time). A crude rate is actually the weighted average of subgroup rates, with the weights being the size of the subgroups.
A specific rate is calculated for designated subgroups or strata of the population.
What is the epidemiological triad of disease?
What are secular trends?
or long-term variation. Gradual changes in outcome occurrence over time.
What are cyclic changes?
recurrent alterations in the frequency of outcome (e.g. seasonal variation)
What is an endemic?
the constant presence of a disease within a given geological area or population group. May also refer to the usual/expected amount of a given disease within such an area or group
EX: malaria in Amazon rainforests of Brazil, chickenpox in the US
What is an epidemic?
The occurrence in a community or region of cases of an illness, specific health-related behavior, or other health-related events clearly in excess of normal expectancy. Is relative to usual frequency of the disease.
What is a pandemic?
An epidemic occurring worldwide, or over a very wide area, crossing international boundaries, and usually affecting a large number of people.
What are some factors that may be associated with increased risk of human disease?
What are the modes of disease transmission?
What is nonclinical (inapparent) disease?
