Epib Final

Moderators

Factors that influence the relationship between exposures and outcomes

Mass Screening

Screen large proportions of the population for a given disease, i.e. BP screenings

Selective Screening

Screen only those who are considered to be at higher risk of disease, i.e. Prostate Cancer

Reliability

Produces stable and consistent results when administered repeatedly

Validity

Test can accurately distinguish between those who have the disease and those who do not

Measures of Validity

1. Sensitivity

2. Speceficity

3. Predictive Value

True Positive (TP)

Actually positive and test agrees

False Positive (FP)

Actually negative and test disagrees

False Negative (FN)

Actually positive and test disagrees

True Negative (TN)

Actually negative and test agrees

Sensitivity

The proportion of people w a disease who are correctly identified by the test as positive for the disease, also called the True Positive Fraction

Specificity

The proportion of healthy people who are correctly identified by the test as negative for the disease, also called the True Negative Fraction

Negative Predictive Value (NPV)

The ability of a test to identify true negatives, what percentage of those testing negative are actually healthy?

Positive Predictive Value (PPV)

The ability to test and identify true positives, what percentage of those testing positive actually have the disease?

Necessary and sufficient

Only X is needed to cause Y

Necessary but not sufficient

X must be present when Y is present, but Y is not always present when X is

Sufficient but not necessary

X is one of the causes of disease, but there are other causes

Neither necessary or sufficient

X may or may not be present when Y is, if X is present with Y, some other factors must be too

Agent = Entity (pathogen)

Causes the disease

Necessary but not sufficient for infectious disease to develop, the agent must be capable of infecting host

Host

Organisms infected with the agent, usually humans and animals

Environment

Can serve as a reservoir for the survival of infectious agents

Attack Rate

Frequently used to describe the incidence of foodborne illness, infectious disease, and other acute epidemics

Direct Transmission

Immediate transfer of infectious agents between previous host and new host

Indirect Transmission

Transfer with something bridging the gap between previous host and new host

Vehicle-borne infections

The agent is carried by inanimate things such as water or objects

Vector-borne infections

The agent is carried by a living thing, such as insects

Fomite-borne infections

The agent is carried by contaminated objects or surfaces

Infectivity

The proportion of exposed individuals who become infected (regardless of whether they become ill)

Pathogenicity

The proportion of exposed individuals who become ill (clinically apparent causes)

Virulence

A measure of disease severity (proportion of cases that result in death)

Primary Prevention

Occurs prior to onset of disease or injury

Secondary Prevention

Occurs early in pathogenesis, designed to reduce disease progress, provide prompt treatment, and prevent disability

Tertiary Prevention

Occurs late in pathogenesis, designed to halt or limit disease progression, limit disability

Risk Assessment

To estimate the health risks of specific exposures, critical for policy decisions

Hazard identification

Examines the evidence that associates exposures to an agent with its toxicity

Dose-Response Assessment

Measures relationship between amount of exposure and occurrence of adverse health effects

Exposure Assessment

Identifies exposed population and estimates the exposure

Risk characterization

Estimates the number of excess unwarranted health events expected

Risk Management

Implements policies to reduce exposures to risks

Individual

Knowledge, attitudes, skills, behaviors

Interpersonal

Friends, family, social networks

Institutional

Organizations, schools, workplaces

Community

Cities, neighborhoods, resources, norms

Policy

Federal, state, local legislation