Epidemiology - Block 1

davidwurbel7's version from 2015-05-28 20:42


Question Answer
A physiological/psychological dysfunctionDisease
A subjective state of the person who feels aware of not being wellIllness
A state of social dysfunction, i.e., a role that the individual assumes when illSickness
The study of how disease is distributed in populations and the factors that influence or determine this distribution and the study of the distribution and determinants of health-related states or events in specific populations and the application of this study to control health problemsEpidemiology
Greater number of cases of a disease than expected in a given populationEpidemic
Constant presence of disease in a particular locality, region or peopleEndemic
Epidemic that spreads through human populations across a large region, continent, or even worldwidePandemic
Safeguarding and improving the physical, mental and social well-being of the community as a whole through an organized community effortPublic Health
Examines the natural history and distribution of a disease in a population based on Time, Person and PlaceDescriptive Epidemiology
Triad consists of host factors, agent and environmentAnalytical Epidemiology
Natural habitat of the infectious agent; any person, animal, arthropod, plant, soil, or a combination of theseReservoir
An animate intermediary in disease transmission. Most are arthropods such as mosquitoes, fleas, or ticksVectors
Inanimate objects such as food, water, biologic products (e.g. blood), and fomites that may indirectly transmit an infectious agent from a reservoir to a hostVehicle

Frequency Measurements - Incidence and Prevalence

Question Answer
Monitoring the progress of a disease in a communitySurveillance
Based on public health legislation, refers to daily, weekly, monthly contacting physicians, laboratories, schools to actively search for cases. Used during outbreaks to identify additional casesActive Surveillance
Reporting of cases by health care providers on a periodic and consistent way. Usually through legislatively mandated reporting of certain conditionsPassive Surveillance
Monitoring of rate of occurrence of specific conditions to assess the stability or change in health levels of a populationSentinel Surveillance
Number of cases of disease or other health phenomenon being studiedCount
Number of events for the time reported divided by total population of an area for the time reportedRatio
The number of new cases during a time periodIncidence
Number of new cases divided by population at riskIncidence Risk
The number of existing cases at or over a point in timePrevalence
Number of existing cases divided by populationPrevalence Risk
The number of new cases of a disease in a specified period of time divided by the population at risk during the same time periodCumulative Incidence
New cases occurring in a given period divided by the total person-time of observationIncidence Density
The proportion of persons in the population who have a particular disease at a given timePrevalence Rate
All cases during a given time period divided by the total population during the same time periodPrevalence Rate
Examines prevalence at a single point in timePoint Prevalence
Examines prevalence over a longer periodPeriod Prevalence
The best measure of risk of a disease is theIncidence Rate
Incidence times the Duration (I x D)Prevalence
Number of new cases among contacts of known cases of specific groupsSecondary Attack Rate
Cases among contacts of primary cases during the period divided by the total number of contacts at riskSecondary Attack Rate
Rate of death in a population at riskMortality Rate
The proportion of population dying every yearCrude Mortality Rate
All deaths during a calendar year divided by the Population at midyearCrude Mortality Rate
The number of deaths in the first year after live birthInfant Mortality Rate
Deaths infants under 1 year old in a given year divided the number of Live births in the same yearInfant Mortality Rate
The proportion of the overall mortality ascribed to a specific diseaseProportionate Mortality Rate
Deaths assigned to the specified disease in a time period divided by the Total number of deaths from all causes during the same periodProportionate Mortality Rate
Deaths from a specific disease per number of persons with the diseaseCase-Fatality Rate
Deaths assigned to the disease in a time period divided by the Total number of people with disease in the same time periodCase-Fatality Rate
Incidence rate in exposed divided by incidence rate in unexposedRelative Risk
Incidence rate in exposed minus the incidence rate in unexposedAttributable Risk
Incidences for exposed group – Incidences for unexposed group divided by the Incidences for the exposed group x 100%Attributable Proportion

Study Designs

Question Answer
Case reports, Case series, Correlational / Ecological studies, Cross-Sectional Surveys are type of what study typeDescriptive Studies
Case-control and Cohort studies are of what study typeAnalytic Studies (Observational)
Randomized controlled trial and Cross over trials are of what study typeAnalytic Studies (Interventional)
Report of the events of one patient; Document unusual medical occurrences and may lead to the identification of a new diseaseCase Report
Describe the experience of a group of patients with the same diagnosis; Document unusual medical occurrences and may lead to the identification of a new disease; Is usually 5-10 people but can be up to 100Case Series
Draw backs to these studies include often based on the experience of only one or a few patients; Presence of a risk factor may only be coincidental; Can not test for the presence of a valid statistical association; There is no comparison groupCase Report and Case Series
Also called Prevalence Surveys; Exposure and disease are measured simultaneously; Provides a “snapshot” of the populationCross-Sectional Study
The benefits of this study include to ability to use the provided information on prevalence of disease (disease load) and health outcomes; Allows administrators to assess health status and needs of the population; Used to formulate hypothesesCross-Sectional Study
The draw backs to this study include only gathering prevalent not incident data; Since both exposure and disease are assessed at the same time you can not determine whether exposure preceded or resulted from disease “chicken or egg” dilemma = no temporal sequence; Usually can not be used to test a hypothesisCross-Sectional Study
This study investigates a possible exposure-disease relationship; Uses populations as unit of analysis; Populations can be countries, counties, provinces etc; Uses database from entire populations to compare frequency of a particular disease in relation to some factorCorrelational (Ecological) Studies
Incorrectly assuming that an association on a population level reflects association on a individual levelEcological Fallacy
Graphical method to display the relationship between two variables; Plots pairs of bivariate observations (x, y) on the X-Y plane; Y is called the dependent variable; X is called an independent variableScatter Diagram

Statistical Analysis

Question Answer
Way of determining the position of a straight line is to use the method of least squares or regression. The “best fitting line” is called theRegression Line
A statistic that summarizes the size and direction of a relationship between 2 variablesCorrelation Coefficient
r, measures the strength of bivariate association or relationCorrelation Coefficient
Gives a prediction equation that estimates the values of y for any given xRegression Line
Measures the proportion of the total variation in y which is explained by x (r2)Coefficient of Determination

Graphical Correlation of r Value

Question Answer
An r value of absolute 0.5 or greater means the relationship isStrong Correlation
An r value of absolute 0.01 to 0.49 means the relationship isWeak Correlation
An r value of 0 means the relationship isNo Correlation
A circular scatter plot or an elliptical scatter plot, with a horizontal line through its longest part, indicates no relationship between X and YNo Correlation
When the line through the longest part of the ellipse either slopes up or down there is a relationship between X and YCorrelation


Question Answer
Actions aimed to promote and preserve health; eradicating, eliminating, or minimizing the impact of injury, disease and disabilityPrevention
Actions taken to prevent the occurrence of a diseasePrimarily Prevention
Actions taken to detect a disease at an early stage when a disease is more easily treatedSecondary Prevention
Actions taken to treat and manage a patient after the symptoms of a disease appear to limit the complications and disabilities associated with the diseaseTertiary Prevention
Agency involved in developing and applying prevention and education activities to improve the health of the people of the U.S.CDC