NURS 340 - Basic Epidemiology & Public Health Surveillance

epidemiology

the study of the occurrence and distribution of health-related states or events in specified populations, including the study of the determinants influencing such states, and the application of the knowledge to control the health problems

epidemiology

the study of what is upon the people

descriptive epidemiology

type of epidemiology: investigates distribution

descriptive epidemiology

type of epidemiology: seeks to describe the occurrence of a disease in terms of person, place, and time

descriptive epidemiology

type of epidemiology: investigates the distribution or the patterns of health events in populations to understand health outcomes

descriptive epidemiology

type of epidemiology: What is the outcome? Who is affected? Where are they? When do events occur?

descriptive epidemiology

type of epidemiology: develops a possible hypothesis regarding a cause and effect relationship

analytic epidemiology

type of epidemiology: investigates determinants

analytic epidemiology

type of epidemiology: looks at the etiology, origin, or cause of disease patterns

analytic epidemiology

type of epidemiology: How does it occur? Why are some people affected more than others?

analytic epidemiology

type of epidemiology: conducts studies to confirm or reject the hypothesis made in descriptive epidemiology

- monitor the health of the population

- understand the determinants of health and disease in communities

- investigate and evaluate interventions to prevent disease and maintain health

epidemiology studies populations to:

Hippocrates

one of the first people to use the ideas that are now part of epidemiology

Hippocrates

used descriptive epidemiology to look at how health is influenced by personal characteristics, place, and time

examined health and disease in a community by looking at geography, climate, the seasons of the year, the food and water consumed, and the habits and behaviors of the people

John Snow

the father of epidemiology

John Snow

by mapping cases that clustered around one public water pump during a London cholera outbreak, he was able to show how the water supply and cholera were associated

Florence Nightingale

contributed to the development of epidemiology in her work with British soldiers during the Crimean War

Florence Nightingale

using simple epidemiologic measures, she was able to show that improving environmental conditions and adding nursing care decreased the mortality rates of the soldiers

multifactorial etiology

during the 20th century, an epidemiology shift occurred from looking for single agents, such as the infectious agent that causes cholera, to determining the _____

multifactorial etiology

includes the many factors or combinations of factors that contribute to disease

genetic and molecular techniques

the development of _____ increased the ability of the epidemiologist to classify persons in terms of exposures or inherent susceptibility to disease

examples included the identification of genetic traits that indicated an increased risk for breast cancer and markers that identified exposures to environmental toxins such as lead or pesticides

- looks at health and disease causation

- surveillance and monitoring of disease trends

- care of clients, families, and population groups in the community

nurses' involvement in epidemiology:

proportion

a type of ratio in which the denominator includes the numerator

rate

a measure of the frequency of a health event in different populations at certain periods

attack rate

the proportion of persons who are exposed to an agent and develop the disease

used in infectious disease investigations

risk

refers to the probability that an event will occur within a specified time period

relative risk

an estimation of the risk of acquiring a problem for those exposed compared with those unexposed

high-risk population

includes those persons who, because of exposure, lifestyle, family history, or other factors, are at greater risk for disease than the population at large

incidence

refers to the occurrence of new cases of a disease or injury in a population during a specified time

incidence rate

quantifies the rate of development of new cases in a population at risk

incidence rate

number of new cases of disease or injury during specified period / time each person was observed, totaled for all persons

incidence proportion

measures the risk of disease or the probability of developing disease during the specified time period

indicates the proportion of the population at risk that experiences the event over some period of time

incidence proportion

number of new cases of disease or injury during specified period / size of population at start of period

prevalence

the number of existing cases of a disease in a specific population over a specified period of time

prevalence proportion

a measure of existing disease in a population at a particular time

prevalence proportion

useful in planning health care services because they indicate the level of disease existing in the population and therefore the size of the population in need of services

prevalence proportion

all pre-existing cases during a given time period / the population during the same time period

case fatality rate

the proportion of persons diagnosed with a particular disease who die within a specified period

case fatality rate

considered an estimate of the risk for death within that period for a person newly diagnosed with the disease (e.g., the proportion of persons with a disease who die during the natural history of the disease)

case fatality rate

number of deaths from a specific disease / number of persons diagnosed

crude mortality rate

an annual rate that represents the proportion of a population who die from any cause during the period, using the midyear population as the denominator

crude mortality rate

number of deaths from any cause during a specified period / estimated mid-year population

proportionate mortality ratio

the proportion of all deaths resulting from a specific cause

proportionate mortality ratio

number of deaths from a specific disease / total number of deaths in the same period

infant mortality ratio

number of infant deaths before 1 year of age in a year per number of live births in the same year

infant mortality ratio

used around the world as an indicator of overall health and availability of health care services

infant mortality ratio

KEY indicator to look at because it determines the healthcare system, family system, and overall health of the community

infant mortality ratio

number of deaths of infants < 1 year of age in a year / number of live births in the same year

neonatal mortality ratio

number of infant deaths under 28 days of age in a year per number of live births in the same year

neonatal mortality ratio

number of deaths of neonates > 28 days of age in a year / number of live births in the same year

cause-specific mortality rate

number of deaths from a specific cause per midyear population

cause-specific mortality rate

an estimate of the risk for death from some specific disease in a population

morbidity

related to disease or disability

mortality

related to death

endemic

normal occurrence of a condition

epidemic

much greater than normal occurrence of a condition

pandemic

an epidemic on multiple continents

incidence

rate or risk of developing a condition

prevalence

proportion of the population with a condition

herd immunity

a large portion of the population is immune

herd immunity

can be provided when a large percentage of the population have either been vaccinated or have had the disease

host, agent, environment

these three elements make up the epidemiologic triangle:

host

part of the epidemiologic triangle: a living species (human or animal) capable of being infected or affected by an agent

host

part of the epidemiologic triangle: genetic susceptibility, immutable characteristics (age, sex), acquired characteristics (immunologic status), lifestyle factors (diet, exercise)

agent

part of the epidemiologic triangle: an animate or inanimate factor that must be present or lacking for a disease or condition to develop

agent

part of the epidemiologic triangle: infectious agents (bacteria, viruses, fungi, parasites), chemical agents (heavy metals, toxic chemicals, pesticides), physical agents (radiation, heat, cold, machinery)

environment

part of the epidemiologic triangle: all that is internal or external to a given host or agent that is influenced and influences the host and/or agent

environment

part of the epidemiologic triangle: climate (temperature, rainfall), plant and animal life (agents, reservoirs, or habitats for agents), human population distribution (crowding, social support), socioeconomic factors (education, resources, access to care), working conditions (levels of stress, noise, satisfaction)

epidemiologic triangle

changes in one of the elements of the _____ can influence the occurrence of disease by increasing or decreasing a person's risk for disease

preclinical stage, clinical stage, resolution stage

stages of the natural history of disease:

preclinical stage

stage of the natural history of disease: exposure to causative agent, no symptoms present

clinical stage

stage of the natural history of disease: symptoms present

resolution stage

stage of the natural history of disease: problem resolved, return to health or chronic state or death

primary prevention

level of prevention: refers to interventions that promote health and prevent the occurrence of disease, injury, or disability

active primary prevention

type of primary prevention: requires a behavior change on part of the subject

passive primary prevention

type of primary prevention: does not require a behavior change

secondary prevention

level of prevention: refers to interventions designed to increase the probability that a person with a disease will have that condition diagnosed early enough that treatment is likely to result in a cure

secondary prevention

level of prevention: occurs to reduce the progress of the disease

secondary prevention

level of prevention: the disease already exists in the person, the goal is to detect

health screenings

at the core of secondary prevention

tertiary prevention

level of prevention: includes interventions aimed at limiting disability and interventions that enhance rehabilitation from disease, injury, or disability

tertiary prevention

level of prevention: the disease has already occurred

tertiary prevention

level of prevention: physical therapy for stroke victims, halfway houses for recovering alcoholics

screening

involves the testing of groups of individuals who are at risk for a specific condition but do not have symptoms

NOT a diagnostic test

to determine the likelihood that these individuals will develop the disease

what is the goal of health screening?

reliability

reviewing a screening test: the precision of the measure (i.e., its consistency or repeatability)

reliability

reviewing a screening test: How often does it work? What is the efficacy? Does it work 60% of the time? 75% of the time?

validity

reviewing a screening test: the accuracy of the measure (i.e., whether it is really measuring what we think it is and how exact the measurement is)

validity

reviewing a screening test: how close are the results to other screening tools used to measure the same thing?

validity

reviewing a screening test: measured by sensitivity and specificity

sensitivity

measure of validity: quantifies how accurately the test identifies those with the condition or trait

sensitivity

measure of validity: represents the proportion of persons with the disease whom the test correctly identifies as positive (true positives)

specificity

measure of validity: indicates how accurately the test identifies those without the condition or trait

specificity

measure of validity: represents the proportion of persons whom the test correctly identifies as negative for the disease (true negatives)

predictive value of the test

a third measure of validity associated with sensitivity and specificity

positive predictive value

measure of validity: the proportion of persons with a positive test who actually have the disease (e.g., the probability that an individual with a positive test has the disease)

negative predictive value

measure of validity: the proportion of persons with a negative test who are actually disease-free

primary data

type of data: first hand data gathered by the researcher himself

primary data

type of data: original data collected for specific epidemiologic studies

primary data

type of data: active surveillance