Week 2 Lesson Objectives and Outline
Chapter 5
Chapter 5 Objectives:
1. Identify epidemiological models used to explain disease and health patterns in populations.
2. Use epidemiological methods to describe the state of health in a community or aggregate.
3. Calculate epidemiological rates in order to characterize population health.
4. Understand the use of epidemiological methods in primary, secondary, and tertiary prevention.
5. Evaluate epidemiological study designs for researching health problems.
OUTLINE:
I. What is epidemiology? The study of the distribution and determinants of health and disease
in human populations.
II. Use of Epidemiology in Disease Control and Prevention
a. Person-Place-Time Model- Person: “Who” factors, such as demographic characteristics,
health, and disease status.
Place: “Where” factors, such as geographic location,
climate and environmental conditions, and political
and social environment.
Time: “When” factors, such as time of day, week, or
month and secular trends over months and years.
b. Descriptive epidemiology- study of the amount of time and distribution of disease;
identified patterns frequently indicate possible causes of disease.
c. Analytic epidemiology- investigation of the causes of disease, or etiology.
III. Epidemiological Triangle- epidemiologist examine the interrelationships between host
and environmental characteristics and uses an organized method of inquiry to derive an
explanation of disease.
IV. Wheel Model of Human-Environment Interaction- the wheel consists of a hub that
represents the host and its human characteristics, such as genetic makeup, personality, and
immunity; surrounding wheel represents the environment, and comprises biological, social,
and physical dimensions.
V. Calculation of Rates- rates are arithmetic expressions that help practitioners consider
a count of an event relative to the size of the population from which it is extracted.
a. Morbidity
i. Incidence- the occurrence of new cases of a disease or condition in a community
over a given period relative to the size of the population at risk for that disease
or condition during that same period.
ii. Prevalence- the number of all cases of a specific disease or condition in a
population at a given point in time relative to the population at the same point
in time.
b. Other Rates- Crude rates: summarize the occurrence of births, mortality, or diseases in
the general population.
Age-specific rates: characterize a particular age group in the population
, and usually consider deaths and births.
Age-adjustment or Standardization of Rates: another method of reducing
bias when there is a difference between the age distributions
of two populations.
Proportionate Mortality Ratio: represents the percentage of deaths resulting
from a specific cause relative to deaths from all causes.
Infant Mortality Rate: calculated by dividing the number of deaths in infants
less than 1 year old by the number of live births for that period.
VI. Concept of Risk- risk refers to the probability of an adverse event; risk factor refers to
the specific exposure factor, such as cigarette smoke, HTN, high cholesterol, excessive
stress, high noise level, or an environmental chemical; attributable risk refers to one
method for comparing two rates is subtracting the rate of nonexposed individuals from the
exposed; relative risk ratio is calculated by dividing the incidence rate of disease in the
nonexposed population; relative risk ratio forms the statistical basis for the risk factor
concept.
VII. Use of Epidemiology in Disease Prevention
a. Levels of Prevention- Primary: interventions occurring before disease development is
primary prevention.
Secondary: occurs after pathogenesis, those measures designed to
detect disease at its earliest stage, namely screening and
physical examinations that are aimed at early diagnosis.
Tertiary: focuses on limitation of disability and the rehabilitation
of those with irreversible diseases such as DM and spinal
cord injury.
b. Establishing Causality- Strength of association: rates of morbidity or mortality must be
higher in the exposed group than in the nonexposed group.
Dose-response relationship: an increased exposure to the risk
factor causes a concomitant increase in disease rate.
Temporally correct relationship: exposure to the causal factor
must occur before the effect, or disease.
Biological plausibility: the data must make biological sense and
represent a coherent explanation for the relationship.
Consistency with other studies: varying types of studies in other
populations must observe similar associations.
Specificity: the exposure variable must be necessary and
sufficient to cause disease; there is only one causal factor.
c. Screening- purpose is to identify risk factors and diseases un their earliest stages.
d. Surveillance- a mechanism for the ongoing collection of community health information;
monitoring for changes in disease frequency is essential to effective and responsive
public health programs.
e. Epidemiological Approaches and Methods- Descriptive: focuses on the amount and
distribution of health and health problems within a population.
Analytic: investigates the causes of disease by determining why a disease rate is lower in
one population group than in another.
Chapter 5
Chapter 5 Objectives:
1. Identify epidemiological models used to explain disease and health patterns in populations.
2. Use epidemiological methods to describe the state of health in a community or aggregate.
3. Calculate epidemiological rates in order to characterize population health.
4. Understand the use of epidemiological methods in primary, secondary, and tertiary prevention.
5. Evaluate epidemiological study designs for researching health problems.
OUTLINE:
I. What is epidemiology? The study of the distribution and determinants of health and disease
in human populations.
II. Use of Epidemiology in Disease Control and Prevention
a. Person-Place-Time Model- Person: “Who” factors, such as demographic characteristics,
health, and disease status.
Place: “Where” factors, such as geographic location,
climate and environmental conditions, and political
and social environment.
Time: “When” factors, such as time of day, week, or
month and secular trends over months and years.
b. Descriptive epidemiology- study of the amount of time and distribution of disease;
identified patterns frequently indicate possible causes of disease.
c. Analytic epidemiology- investigation of the causes of disease, or etiology.
III. Epidemiological Triangle- epidemiologist examine the interrelationships between host
and environmental characteristics and uses an organized method of inquiry to derive an
explanation of disease.
IV. Wheel Model of Human-Environment Interaction- the wheel consists of a hub that
represents the host and its human characteristics, such as genetic makeup, personality, and
immunity; surrounding wheel represents the environment, and comprises biological, social,
and physical dimensions.
V. Calculation of Rates- rates are arithmetic expressions that help practitioners consider
a count of an event relative to the size of the population from which it is extracted.
a. Morbidity
i. Incidence- the occurrence of new cases of a disease or condition in a community
over a given period relative to the size of the population at risk for that disease
or condition during that same period.
ii. Prevalence- the number of all cases of a specific disease or condition in a
population at a given point in time relative to the population at the same point
in time.
b. Other Rates- Crude rates: summarize the occurrence of births, mortality, or diseases in
the general population.
Age-specific rates: characterize a particular age group in the population
, and usually consider deaths and births.
Age-adjustment or Standardization of Rates: another method of reducing
bias when there is a difference between the age distributions
of two populations.
Proportionate Mortality Ratio: represents the percentage of deaths resulting
from a specific cause relative to deaths from all causes.
Infant Mortality Rate: calculated by dividing the number of deaths in infants
less than 1 year old by the number of live births for that period.
VI. Concept of Risk- risk refers to the probability of an adverse event; risk factor refers to
the specific exposure factor, such as cigarette smoke, HTN, high cholesterol, excessive
stress, high noise level, or an environmental chemical; attributable risk refers to one
method for comparing two rates is subtracting the rate of nonexposed individuals from the
exposed; relative risk ratio is calculated by dividing the incidence rate of disease in the
nonexposed population; relative risk ratio forms the statistical basis for the risk factor
concept.
VII. Use of Epidemiology in Disease Prevention
a. Levels of Prevention- Primary: interventions occurring before disease development is
primary prevention.
Secondary: occurs after pathogenesis, those measures designed to
detect disease at its earliest stage, namely screening and
physical examinations that are aimed at early diagnosis.
Tertiary: focuses on limitation of disability and the rehabilitation
of those with irreversible diseases such as DM and spinal
cord injury.
b. Establishing Causality- Strength of association: rates of morbidity or mortality must be
higher in the exposed group than in the nonexposed group.
Dose-response relationship: an increased exposure to the risk
factor causes a concomitant increase in disease rate.
Temporally correct relationship: exposure to the causal factor
must occur before the effect, or disease.
Biological plausibility: the data must make biological sense and
represent a coherent explanation for the relationship.
Consistency with other studies: varying types of studies in other
populations must observe similar associations.
Specificity: the exposure variable must be necessary and
sufficient to cause disease; there is only one causal factor.
c. Screening- purpose is to identify risk factors and diseases un their earliest stages.
d. Surveillance- a mechanism for the ongoing collection of community health information;
monitoring for changes in disease frequency is essential to effective and responsive
public health programs.
e. Epidemiological Approaches and Methods- Descriptive: focuses on the amount and
distribution of health and health problems within a population.
Analytic: investigates the causes of disease by determining why a disease rate is lower in
one population group than in another.
