EPIDEMIOLOGY 3490 EXAM 1

What is the full formal definition of epidemiology?

The study of the distribution and determinants of health-related phenomena in human populations and the application of this study to control health problems.

What are the four embedded components of the definition of epidemiology?

Distribution, Determinants, Population focus, Application

What is distribution in epidemiology?

The pattern of disease by person, place, and time.

What are determinants in epidemiology?

Causes or exposures that influence disease occurrence.

What does 'person' include in epidemiology?

Age, sex, race, occupation, exposure category, clinical features.

What does 'place' include in epidemiology?

Geographic location (country, state, community, facility).

What does 'time' include in epidemiology?

Trends over years, seasons, outbreaks, epidemics.

What is morbidity?

Illness due to a specific disease.

What is mortality?

Death from a specific cause.

Why is epidemiology population-based?

It examines disease patterns among groups, not individuals.

What is endemic?

Steady-state presence of disease in a population.

What is sporadic?

Irregular, infrequent cases.

What is an epidemic?

Occurrence in excess of expected baseline.

What is a pandemic?

Worldwide epidemic.

What is an outbreak?

Localized epidemic.

When can one case be considered an epidemic?

When the disease is normally absent from that population.

What is an infectious disease?

Transmissible disease caused by an infectious agent.

What is a non-infectious disease?

Non-transmissible disease caused by other factors.

How is obesity classified in terms of epidemic?

Non-infectious epidemic.

How is H1N1 classified in terms of epidemic?

Infectious epidemic.

How many H1N1 cases were there in the U.S. in 2009?

~60 million.

What was the most affected age group in H1N1?

18-64 years.

How many Ebola cases were reported in April 2016?

28,652.

How many Zika cases were reported in Brazil in January 2016?

3,520.

What was the agent of the Chipotle outbreaks in 2015?

E. coli.

What is the prevalence of cyberbullying?

~15%.

What is the prevalence of physical bullying?

~20%.

What are the waves of the opioid epidemic?

Prescription opioids, Heroin, Synthetic opioids (fentanyl).

What are the three components of surveillance?

Data collection, Analysis, Dissemination.

What is the epidemic threshold?

Minimum number of cases indicating epidemic.

Who are EIS officers?

CDC disease detectives.

What disease did John Snow investigate?

Cholera.

What was Snow's hypothesis?

Waterborne transmission.

What were the cholera deaths per 10,000 houses in Southwark & Vauxhall?

315.

What were the cholera deaths per 10,000 houses in Lambeth?

37.

Why is John Snow's work important?

Early analytic comparison of exposure groups (natural experiment).

What are disappearing disorders?

Controlled through vaccines, sanitation, antibiotics.

What are residual disorders?

Causes known, control poorly implemented.

What are persisting disorders?

No effective prevention or cure.

What are new epidemic disorders?

Increasing due to lifestyle, environment, aging.

Why might disease rates appear to increase?

Better diagnosis, Improved reporting, Screening, Aging population, Case definition changes.

What is demographic transition?

Shift from high birth/death rates to low birth/death rates.

What is epidemiologic transition?

Shift from infectious to chronic diseases as leading causes.

What is the double burden of disease?

Presence of both infectious and chronic diseases (often developing countries).

What does an expansive pyramid shape indicate?

Wide base; high birth rate (developing country).

What does a constrictive pyramid indicate?

Narrow base; aging population (developed country).

What type of pyramid does Kenya have?

Expansive.

What type of pyramid does Japan have?

Constrictive.

What type of pyramid does the U.S. have?

More rectangular/stable but aging.

What is a fixed population?

Membership defined by event; no new members added.

What is an example of a fixed population?

9/11 survivors.

What is a dynamic population?

Membership changes through births, deaths, migration.

What is the first use of epidemiology?

Descriptive epidemiology.

What is the second use of epidemiology?

Study functioning and improvement of health services.

What is the third use of epidemiology?

Analytic epidemiology to identify causes.

What is the fourth use of epidemiology?

Risk assessment.

What is the fifth use of epidemiology?

Grouping symptom patterns.

What is the sixth use of epidemiology?

Describe natural history of disease.

What is the seventh use of epidemiology?

Analytic epidemiology.

What is primordial prevention?

Prevent development of risk factors through social/environmental change.

What is primary prevention?

Prevent disease before it occurs in healthy individuals.

What is active primary prevention?

Requires behavior change (e.g., wearing helmets).

What is passive primary prevention?

No behavior change required (e.g., water fluoridation).

What is secondary prevention?

Early detection before symptoms (screening).

What is tertiary prevention?

Reduce disability after disease occurs (rehabilitation).

What is Big Data?

Extremely large, complex electronic datasets that require advanced systems for storage and analysis.

Example:

Electronic medical records across all U.S. hospitals.

What are the Three V's of Big Data?

Volume, Variety, Velocity.

Volume

Massive amounts of data that strain traditional storage systems.

Example: Millions of patient records.

Variety

Data in multiple formats (structured and unstructured).

Example: Lab results + X-rays + physician notes + social media posts.

Velocity

Speed at which data are generated and processed.

Example: Real-time tracking of ER visits for flu.

Nature of the Data

The source or origin of the data.

Examples:

Vital statistics, case registries, medical records, surveys.

Availability of Data

The degree to which investigators can access data.

Example: HIPAA restricts access to identifiable patient records.

Representativeness

Degree to which a sample reflects its parent population.

Example: A national random sample better represents the U.S. than a single-city sample.

Generalizability (External Validity)

Ability to apply study findings to populations not in the study.

Example: Results from adults may not generalize to children.

Thoroughness

Extent to which all cases are identified, including subclinical cases.

Example: Testing asymptomatic contacts in an outbreak.

Strengths vs. Limitations of Data

Evaluation of how useful a dataset is and what biases it may contain.

Example: Death certificates are good for mortality rates but poor for determining cause accuracy.

Privacy Act of 1974

Prohibits release of confidential data without consent.

Freedom of Information Act (FOIA)

Requires government transparency except for personal/medical records.

Public Health Service Act

Protects confidentiality of data collected by certain federal agencies.

HIPAA (1996)

Protects individually identifiable health information.

Vital Registration System

System that records vital events.

Vital events include:

Births, deaths, marriages, divorces, adoptions.

Birth Certificate

Official record of live birth including maternal and infant data.

Example variables:

Mother's age, congenital anomalies.

Death Certificate

Official record of death including demographic info and cause.

Includes:

Immediate cause + contributing causes.

Limitations of Mortality Data

Misclassification

Stigma

Coding changes

Diagnostic inaccuracies

Example: AIDS deaths underreported early in epidemic.

International Classification of Disease (ICD)

Standardized coding system for diseases.

Exam tip: Sudden trend shifts may reflect coding changes.

Reportable Diseases

Diseases legally required to be reported to public health authorities.

Examples:

Tuberculosis, measles, Salmonella.

Limitations of Reportable Disease Data

Underreporting

Asymptomatic cases missed

Mild conditions ignored

Public Health Information Cycle

Provider → Local → State → CDC → WHO

BRFSS

Behavioral Risk Factor Surveillance System; monitors behavioral risks for chronic disease.

Examples:

Smoking, physical inactivity.

Case Registry

Centralized database of disease cases.

SEER Program

Cancer registry collecting incidence, mortality, survival data.

U.S. Census

Population count conducted every 10 years; provides demographic data.

Used for: Denominators in rate calculations.

Qualitative (Categorical) Data

Non-numeric categories.

Example: Sex, marital status.

Nominal Scale

Categories without order.

Example: Blood type.

Ordinal Scale

Ordered categories without equal spacing.

Example: Mild, moderate, severe.

Quantitative Data

Numeric measurements.

Discrete Data

Countable integers.

Example: Number of ER visits

Continuous Data

Measured on a continuum.

Example: Blood glucose level.

Frequency Table

Table showing counts per category.

Bar Chart

Displays frequency of categories.