Biostats Epidemiology Flashcards
Father of epidemiology
John Snow
It was thought that
diseases were caused by
________, a poisonous
vapor or mist filled with
particles from decomposed matter
(________) that caused illnesses. It was
identifiable by its foul smell
“Miasma”, miasmata
By the help of
Epidemiology, the
__________________ was
supplanted by the “Germ
theory” – most diseases
are caused by an
infectious agent
“Miasmatic theory”
Epi = ?
upon
Demos = ?
Population
Logos = ?
Study of
The study of the distribution and determinants of health related states or events in specified human populations and its application to the control of health problems
Epidemiology
The branch of medical science which
treats of epidemics
Epidemiology
is the study of “epidemics”
and their prevention
Epidemiology
Current scope of Epidemiology:
- endemic communicable diseases
- non-communicable infectious diseases
- chronic diseases, injuries, birth defects, maternal child health, occupational health, and environmental health
- health-related behaviors: exercise, seat belt use
Includes Frequency and pattern
Distribution
the number of health events (e.g. number of cases of diabetes in a population), also the relationship of
that number to the size of the population
Frequency
the occurrence of health-related events by time, place, and person
Pattern
annual, seasonal, weekly, daily, hourly, weekday versus weekend,
Time patterns
geographic variation, urban/rural differences, and location of work sites or schools
Place patterns
demographic factors (age, sex, marital
status, and socioeconomic status), as well as behaviors and environmental exposures
Personal Characteristics
Causes and other factors that influence the occurrence of disease and other health-related events
Determinants
_______ does not occur randomly in a population, but happens only when the right accumulation of ____________ or determinants exists in an individual
Illness, risk factors
- Discover the agent, host, and environmental factors that affect health
- Determine the relative importance of causes of illness, disability, and death
- Identify those segments of the population that have the greatest risk from specific causes of ill health
- Evaluate the effectiveness of health programs and services in improving population health
Epidemiology Purposes
in Public Health Practice
AIMS OF EPIDEMIOLOGY
- Describe the health status of population
- Explain the etiology of disease
- Predict the frequency and distribution of disease
- Control diseases in populations
USES OF EPIDEMIOLOGY
Determine the magnitude and trends
Identify the etiology or cause of disease
Determine the mode of transmission
Identify risk factors or susceptibility
Determine the role of the environment
Evaluate the impact of the control measures
Host
*Demographic characteristics
*Biological characteristics
*Socioeconomic characteristics
Agents
*Biological agents
*Physical agents
*Chemical agents
*Nutrient agents
*Mechanical agents
*Social agents
Environment
*Physical environment
*Biological environment
*Social environment
Solving Health problems
Step 1: Data collection
Step 2: Assessment
Step 3: Hypothesis Testing
Step 4: Action
disease occurrence among a population that is in excess of what is expected in a given time and place.
epidemic or outbreak
group of cases in a specific time and place that might be more than expected.
cluster
disease or condition present among a population at all times.
endemic
a disease or condition that spreads across regions.
pandemic
number of cases occurring during a specific period; always dependent on the size of the population during that period.
rate
Increasing amount of disease
Sporadic > Endemic > Epidemic > Pandemic
Epidemiology Study types
Experimental
Observational
Examining the distribution of a disease in a population, and observing the basic
features of its distribution in terms of time, place, and person
DESCRIPTIVE EPIDEMIOLOGY
Testing a specific hypothesis about the relationship of a disease to a putative cause, by conducting an epidemiologic study that relates the exposure of
interest to the disease of interest
ANALYTIC EPIDEMIOLOGY
Typical study design:
community health survey (approximate synonyms - cross-sectional study,
descriptive study)
Descriptive epidemiology
Typical study designs:
cohort, case-control
Analytic epidemiology
When was the
population affected?
Where was the
population affected?
Who was affected?
Descriptive epidemiology
How was the
population affected?
Why was the
population affected?
Analytic epidemiology
Tests hypotheses about:
* Why
* How
Comparing groups with different rates of disease occurrence and with differences in demographic characteristics, genetic or
immunologic make-up, behaviors, environmental exposures, and other potential risk factors
ANALYTIC EPIDEMIOLOGY
An epidemiologist:
Counts
Divides
Compares
To measure frequency of a disease or event, pay attention to the numerator (cases) and the denominator (population at risk)
Measuring Frequency
MEASURES OF DISEASE
FREQUENCY
- ratios
- proportions
- prevalence, incidence
- risks, rates, odds
all functions of numerators (cases) and
denominators (population at risk or those at risk but disease free)
the relative magnitudes of two
quantities (usually expressed as a
quotient) (A/B)
Ratio
a ratio that relates the part
(the numerator) to the whole (the
denominator) — numerator always part
of the denominator (A/A+B)
Proportions
The total number of cases (existing cases) of the disease in the population at a given time
Prevalence
The total number of cases in the population, divided by the number of individuals in the population
Prevalence
It is a proportion and is usually expressed as a percentage
Prevalence
The total number of NEW cases of the disease in a population at risk of the disease in a defined time period
Incidence
The total number of NEW cases in the population, divided by the total number of individuals at risk of the disease in the population
Incidence
Again, it is a proportion (RISK) and can be
expressed as a percentage
Is number of events over number of possible
events
Risk
Is defined as the number of events to the
number of non-events
Odds
velocity at which new cases of a particular disease (or outcome of interest) occur in a population at risk for the disease
Rate
- Compare a group of individuals with disease (“case” group) and a
group (“control” group) without disease with respect to the factor
of interest (exposure/treatment) - Retrospective or prospective
Case Control
A sample of a reference population is examined at a given point in
time
Cross-sectional
- A sample of a reference population is examined at a given point in
time - A “cohort” is defined and individuals are classified as to exposure
levels - Study participants are followed over time and assessed for the
development of disease
Cohort
