Epi. Test #1

The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to control of health problems.
Epidemiology is an ______________ science that capitalizes upon naturally occurring situations in order to study the occurrence of disease.
_______________ epidemiology refers to epidemiologic studies concerned with characterizing amount and distribution of health and disease within a population.
– concerned with characterizing amount and distribution of health and disease within a population.
____________ epidemiology examines casual (etiologic) hypotheses regarding association between exposures and health conditions.
– examines causal (etiologic) hypotheses regarding association between exposures and health conditions
Contact with a disease-causing factor or amount of that factor that impinges on group or individual.
All possible results that may occur from exposure to casual factor.
Person who has been diagnosed with health-related state or event.
Ability of a program to produce desired effect among those who participate in program compared to those who do not.
Ability of a program to produce benefits among those who are offered the program.
Occurrence of cases of an illness, specific health-related behavior or other health-related events clearly in excess of normal expectancy.
Occurrence of diseases and other health outcomes vary in population, with some subgroups more affected than others.
Any factor that brings about change in a health condition or other defined characteristics.
Illnesses due to specific disease or health outcome.
Causes of death.
Agent, Host, Environment
What Causes Disease: Three Factors:
1. ____________: What caused the disease? Microbes, toxins, carcinogens, blunt force, etc.
2. ___________: Who has the disease? Genetic or personal characteristics.
3. ____________: Where was the disease transmitted? Air pollution, weather, climate, social situations, etc.

A.K.A. Three Concepts of Epidemiologic Triangle

Epidemiological Triangle
_______________ ______________:
Host <---> Environment <---> Agent <--->
Object that can be infectious agent and capable of being means of production.
Invertebrate animal capable of transmitting infectious agent from infected or human to other susceptible animals or humans.
Habitat in or on which infectious agent lives, grows, and multiplies and on which depends for survival.
Infection that travels from animals to humans.
__________ Transmission:
Direct and usually immediate transfer of infectious agents to portal of entry.
Vehicle, Airborne, Vector
Indirect Disease Transmission:
__________-Borne Infections: infection results from contact with vehicles (contaminated, non-moving objects) Ex. Unsanitary food, objects.
__________ Infections: Spread of droplet particles present in the air. Ex. classrooms, airplanes.
__________-Borne Infections: Infection resulting from vector. Ex. animal, human.
Infection Model
Chain of __________ ___________:
– Pathogen
– Human reservoir
– Portal of exit
– Transmission
– Establish disease in new host
Susceptibility, Presymptomatic, Clinical, Death
What are the four stages of the naturally history of disease?
1. ____________
2. ____________ Disease
3. ____________ Disease
4. Recovery, Disability, _________
Multi, Model
____________-causation Disease __________:
Primarily relates to chronic diseases that take years to present and are caused by multiple factors. Example: Risk of heart disease increases for people with multiple risk factors such as: smoker, overweight, etc.
Primary, Secondary, Tertiary
Types of Prevention:
_______________: Pre-pathogenesis, prevention of disease before it occurs (Health Promotion)
______________: Early phases of pathogenesis, activities to limit progression of disease (screening)
_____________: later stages of pathogenesis, slow or block progression of disability (rehabilitation)
Ice/__________ Theory:
Unrecognized cases outnumber recognized cases.
– Exceptions are severe, easily diagnosed diseases.
Hippocrates, smallpox
– Greek writer and physician ___________ wrote “On Airs, Waters, and Places”, which suggested that environmental factors implicated in disease causation.
– Epidemic of _________ plague killed up to 1/3 of the population of Europe during 1346-1352.
– Edward Jenner finds __________ vaccine in 1789.
Flu, penicillin, 1949
– 1918 ______ Pandemic, killed 50-100 million people around the world.
– Alexander Fleming discovered ___________ in 1928.
– 1948 Framingham Study: Longitudinal cohorts study.
– Center For Disease Control and Prevention created in _______.
– 1964 Smoking and Lung Cancer.
Epidemiological Transition
_______________ ________________:
– Describes a shift in patterns of morbidity and mortality from causes related primarily to infectious and communicable diseases to causes associated with chronic, degenerative disease.
Demographic Transition
______________ _______________:
– A shift from high birth rates and death rates found in agrarian societies to much lower birth and death rates in developed countries.
Rose’s Theorem
__________ ___________:
– A large number of people exposed to a small risk may generate many more cases than a small number exposed to a large risk.
Person, place, time
Three Most Important Epi Questions:
___________: How do personal characteristics of members of population affect disease pattern?
___________: How does place in which population lives affect disease pattern?
___________: How does pattern of this disease vary over time in this population?
Discrete, Categorical, Continuous
Epidemiologic Variables:
– ___________ Variables: Have no value difference, groups people into nominal categories. I.e. sex, college status
– Numerical/Quantitative:
1. ____________ Variables: categories that do not represent numerical value. Ex. age group (10-14 yrs, 15-29 yrs), race, blood type, BMI (underweight, healthy, overweight, obese) *think categories*
2. _____________ Variables: have numerical value and infinite possible responses. Gives best info. Ex. age, weight, yearly rainfall, annual salary. *think numbers*
3. Dichotomous: yes/no
Natural Experiments
_____________ _____________:
Naturally occurring circumstances in which subsets of population have different levels of exposure to a supposed casual factor in situation resembling an actual experiment, where human subjects would be randomly allocated to groups.
Active, passive, herd
Immunization: Developing antibodies to disease.
___________ Immunity: body produces its own antibodies.
_________ Immunity: transfer of antibodies from one person to another (typically in breastfeeding).
_________ Immunity: We can protect the herd by the majority of people getting immunized.
Descriptive Epidemiology
_____________ _____________:
– Classifies disease according to variables of person (who), place (where), and time (when)
– Characterizes amount and distribution of health & disease within a population
– Provides info for disease prevention, intervention, and future research.
– Provides clues to identify new disease
– Identify population at greatest risk –> assist in planning and resource allocation –> identify future research to understand relationships between exposure and health outcome.
Types of _______________ Epidemiologic Studies:
– Case Reports
– Case Series
– Cross-Sectional Studies
– Ecologic Studies
Case Reports
________ __________:
– Accounts of a single occurrence or small number of noteworthy event
Case Series
________ _________:
– Large collection of cases of disease
1. Grouped consecutively
2. Lists common features
___________-___________ Studies:
– Examines relationship between disease and other variables of interest as they exist in particular population at particular point in time – presence/absence of disease and other variables
– Can’t determine causality
– Prevalence study – exposures and outcomes assessed at same point in time.
– Used to formulate hypotheses for follow up in analytic studies.
___________ Studies:
– Study where units of analysis are populations or groups of people not individuals.
1. Unit of analysis at the group level
– May be used when individual measurements are not available, but group-level data can be obtained.
1. Ecologic fallacy – predicting individual results based off group studies.
Epidemiologic Measures
___________ ____________:
– Frequency of disease or condition
– Associations between exposures and outcomes
– Strength of relationship between exposure and outcome
___________ Rate:
# of new cases/total population AT RISK
__________ Rate:
– Rate not modified to take into account any other factors.
– Numerator = frequency of disease over time
– Denominator = unit size of population
Case Fatality
____________ ____________ Rate:
– Number of deaths due to disease among people afflicted with disease.
– # of deaths due to disease / # of cases of disease
____________ Rate:
– Number of deaths within a population due to specific disease or cause divided by total number of deaths in population
– # of deaths occurring during a specific time period / Population from which deaths occurred
__________-_________ Rate:
– Mortality (or frequency of disease) divided by population size at midpoint of time period.
– Mortality (or frequency of disease) / Population size at midpoint of time period
______-_________ Rate:
– Number of cases of disease per age group of population during a specific time period
– # of cases among age group / # of people in age group
__________ Rates:
– Statistical procedures have been used to allow for fair comparisons across populations by removing effect of differences in composition of different populations.
– Ex. age adjustment
Bar, line, pie
Graphing Epi. Data:
– _________ chart: frequency of cases
– _________ graph: trends in data
– _________ chart: proportion of cases
Mean, median, mode
Numerical Methods:
Arithmetic _________: Average
____________: Middle
___________: Most common
Range, variance, standard
Numerical Methods:
__________: Difference between largest and smallest values.
__________: What’s the spread from lowest to highest; average of squared differences of observations from mean.
__________ Deviation, square root of the variance.
Inference, estimate, interval, power
Role of Chance:
_____________: Taking observation & making generalizations. Sample to population.
Point _________: Single value which represents population parameter.
Confidence ____________ Estimate: Range of values that with certain degree of probability contain population parameter.
____________: Ability of a study to demonstrate an association if one exists.
Exposure, threshold
Dose Response Relationship:
– As level of __________ increases, level of outcome increases.
– ____________: Lowest dose where a particular response occurs; when maximum response reached curves flattens out.
outcome, immune
Multi-modal Curve:
– Several peaks in frequency of an ____________.
– May be due to latency period, changes in ___________ status, changes in lifestyle.
____________ Curve:
– Graph plotting distribution of cases by time of onset.
– Related to point epidemic
hypotheses, hypotheses
Epidemiologic Research Strategies:
– Examine existing facts & _____________.
– Formulate new or more specific hypotheses.
– Get more facts to test new _____________.
– Defining measurement procedure for variables used in a study.
Ex. defining things like smoking, alcohol use, etc.
Public _________ Surveillance:
– Systematic, ongoing collection, analysis, interpretation, and dissemination of health data. Ex. CDC
Internal, reliability, validity, exposure
____________ Validity: Refers to degree which study has used methodologically sound procedures.
____________: how well can you repeatedly measure the same thing?
____________: is it measuring the same thing you want to measure? (think accuracy)
__________/outcome: accurately classifying people.
____________ Validity: Ability to generalize from results of study to an external population.
– Convenience sample may not have this.
– Random samples more likely to have this than convenient (not always guaranteed).
Random, sampling
___________ Error: Often due to variability (imprecision) in measurement. I.e. How certain are you of a waist:hip ratio? Results in larger standard deviations and confidence intervals.
– More error, less confident you are in your estimate.
____________ Error: Values for sample differ from values in population.
Variability in Measurements: Reliable, valid, reproducible measurements
___________: systematic error that will lead results away from the truth.
Example: Group of obese cases and normal weight controls in a weight loss study.
– During your follow-up measurements, the scale is accurate up to 210 lbs, then increasingly over-estimates weight above 210 lbs.
Hawthorne, Healthy, Selection, Recall, Interviewer
Types of Bias:
___________ Effect: people act different when they know they are being watched.
____________ Worker Effect: healthier people participate more.
____________ Bias: Who chooses to participate & who doesn’t.
_____________ Bias: Not good at remembering details.
_____________ Bias: May ask more detailed questions of cases.
Differential, Non-differential
Misclassification Bias:
_____________ Misclassification: Exposure classification influences differential accuracy in ascertaining outcome information.
_____-______________ Misclassification: Inaccuracies in classifying exposure status of individuals, but these misclassifications occur similarly between exposed and unexposed groups.
______________ Bias: Tendency to “trash” studies with negative results – no findings or opposite of what you were trying to find.
– Weak or variable associations may appear stronger in publication literature than they actually are.
– Associated with the outcome.
– Associated with the exposure.
– Not on the casual pathway between exposure and outcome.
– Influences both variables

<--- Exposure <--- Confounder ---> Outcome

Ways to Reduce __________:
– Develop explicit definitions of exposures and outcomes.
– Enroll all cases in a defined time and region.
– Try for high participation rates.
– Do what you can to ensure reps.
– Use valid and Reliable measures.
Prevalence, Incidence
_____________gives information on new and existing cases,while ______ gives information on new cases.
Agent, Host, Environment
Name the three concepts of the epidemiologic triangle.
Person, Place, Time
Provide a different variable for each of the following key epidemiologic concepts that are used to describe patterns of diseases or exposures.
Frequency, associations, relationship
Epidemiologic measures of association provide what three types of information?
– ___________ of disease or condition
– ____________ between exposures and outcomes
– Strength of ___________ between exposure and outcome
Epidemiologic, Demographic
When a country shifts to higher rates of chronic disease from infectious disease, this is called the ___________ Transition.
This usually happens along with the ______________ transition which is a shift from high birth and death rates to much lower birth and death rates.
Epidemic, Pandemic
When a disease occurs in number greater than would be expected, this is called a/an ____________. When this is worldwide it is called a/an ___________.
tertiary, primary, secondary
A program to promote quitting among those with lung cancer is an example of __________ prevention.
A smoking prevention program
with adolescents is an example of ___________ prevention. An x‐ray to diagnose lung cancer early is an example of ____________ prevention.
John Snow
__________ ___________:
He was considered the father of epidemiology because he was one of the first to use descriptive and analytic approaches to determine the cause of disease.
Disease, health, analytic
What are the three aims of Descriptive Epidemiology?
1. Evaluation of trends in health and __________.
2. Provide bases for planning, provision, and evaluation of _________ services
3. Identify problems to be studied by ___________ epidemiology

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