Nies and

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Nies and
Epidemiology
Nies and McEwen Chapter 4 ATI Chapter 3
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Objectives --Epidemiology

• Objective 1. Define and discuss the following
  terms compare and contrast the following methods
  and concepts of epidemiology related to
  community health
• 1. descriptive epidemiology
• 2. analytic epidemiology
• Objective 2. Define the following epidemiological
  concepts, including their identifying factors and
  interconnection in epidemiology and the disease
  process
• 1. epidemiological triangle
• a. agent
• b. host
• c. environment
• Objective 3. Define and differentiate, and be
  able to calculate, as well as discuss the
  implication of the following epidemiological
  rates
• 1. attack rate
• 2. incidence rate
• 3. prevalence rate
• 4. age-adjusted rate
• 5. proportionate mortality rate
• Objective 4. Define and discuss the concepts of
  risk and risk factors as the two terms relate to
  the epidemiological process
• Objective 5. Define, discuss, and differentiate
  the concepts of screening and surveillance as
  they relate to the epidemiological process
• Objective 6. Define, discuss, and differentiate
  between the concepts of cross-sectional studies
  and retrospective studies.

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• Objective 1. Define and discuss the following
  terms compare and contrast the following methods
  and concepts of epidemiology related to
  community health
• descriptive epidemiology uses person, place, and
  time variables to describe disease patterns.
• analytic epidemiology analyzes complex
  relationships among determinants of diseases.
  The focus is on disease etiology.

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• Objective 2 Define the following epidemiological
  concepts, including their identifying factors and
  interconnection in epidemiology and the disease
  process
• 1. the epidemiological triangle
• a. agent
• b. host
• c. environment

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Objective 2
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Agent Factors
Objective 2

• Nutritive elements
• Chemical agents
• Physical agents
• Infectious agents

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Host Factors
Objective 2
Influence, exposure, susceptibility, or response
to agent

• Genetics
• Age
• Sex
• Ethnic group
• Physiological state
• Prior immunological experience
• Inter-current or preexisting disease
• Human behavior

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Environmental Factors
Objective 2
Influence Existence of the Agent, Exposure, or
Susceptibility to Agent

• Physical environment
• Biological environment
• Socioeconomic environment

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The Epidemiological Triangle
Objective 2
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• Objective 3. Define and differentiate, and be
  able to calculate, as well as discuss the
  implication of the following epidemiological
  rates
• 1. attack rate
• 2. incidence rate
• 3. prevalence rate
• 4. age-adjusted rate
• 5. proportionate mortality rate
•  

Incidence of Rocky Mountain Spotted Fever In The
United States
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Epidemiological Rates
Objective 3

• 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
• Rate Numerator/Denominator
• Number of health events in a specified
  period/Population in same area in same specified
  period k

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Attack Rate
Objective 3

• An attack rate is a special incidence rate that
  documents the number of new cases of a disease in
  those exposed to a disease.

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Incidence Rate
Objective 3

• Incidence rates
• New cases
• Number of New Cases in a Given Time Period
• Population at Risk During Same Time Period
• Example In a total population of 4000, where 250
  individuals already have the disease, 75 new
  cases are reported.
• 75 75
• 4000 250 3750

X 1000


0.02 x 1000 20 per 1000 per time period
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Prevalence Rate
Objective 3

• Prevalence rates
• All cases
• Number of Existing Cases
• Total Population
• Example In a population of 4000 , 250
  individuals have a particular disease.
• 250
• 4000

X 1000
0.0625 X 1000 62.5 per 1000
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Age-Adjusted Rate
Objective 3

• Age-adjustment or standardized rates reduce bias
  due to unequivalent age distribution of the
  populations being compared.

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Proportionate Mortality rate
Objective 3

• The proportionate mortality rate (PMR) represents
  the percentage of deaths resulting from a
  specific cause relative to deaths from all
  causes.

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Comparing Rates
Objective 3

• The occupational health nurse notes that during
  the past year 4 of 628 factory employees have
  developed asbestososis. He checks with MMWR, and
  notes that the incidence rate of asbestososis in
  the general population is 5 per 1000.
• Is the rate for the factory higher or lower than
  for the general population?

Incidence in General Population
Incidence in Factory
5 / 1000 0.005 4
/ 628 0.0064 0.005 X 1000 5 per 1000
0.0064 X 1000 6.4 per 1000
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• Objective 4. Define and discuss the concepts of
  risk and risk factors as the two terms relate to
  the epidemiological process

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Objective 4
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RISK FACTORS
Objective 4

• a. Identification of risk factors is closely
  associated with chronic disease reduction.
• b. Risk factors are variables that have been
  shown to increase the rate of disease in persons
  who have them or have been exposed to them.
• c. Identification of risk factors is critical to
  development of prevention interventions.
• d. Risk is the likelihood that healthy persons
  exposed to a factor will acquire a specific
  disease.
•  e. Risk factor refers to the specific exposure
  factor. Risk factors may be fixed characteristics
  non-modifiable-- (i.e., age, sex, genetics), or
  modifiable--lifestyle factors (dietary habits,
  exercise regimens), or external to the individual
  (i.e., cigarette smoking, stress, noise).

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• Objective 5. Define, discuss, and differentiate
  the concepts of screening and surveillance as
  they relate to the epidemiological process

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Screening
Objective 5

• The purpose of screening programs is to identify
  risk factors and diseases in their earliest
  stages. Screening is usually classified as a
  secondary prevention activity because disease is
  discovered after a pathological change has
  occurred.
• Guidelines for screening programs include
• 1. Adequate and appropriate follow-up should be
  planned for those who test positive.
• 2. Early diagnosis of the disease should be
  beneficial.
• 3. Acceptable and medically sound treatment
  should be available.
• 4. Procedures for ensuring confidentiality should
  be in place.
• 5. Tests must be cost effective and acceptable to
  the client.
• 6. Costs of program, follow-up, and resulting
  medical care should have a bearing on the
  decision to screen.
• 7. Screening tests should ideally have high
  sensitivity (the ability of a test to detect
  those with the disease) and specificity (the
  extent to which a test can identify those without
  the disease)

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Surveillance
Objective 5

• Surveillance allows ongoing collection of
  information by monitoring changes in disease
  frequency and trends in occurrence of risk
  factors.
• The nurse evaluates trends in morbidity by
  identifying new cases and calculating incidence
  rates.

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• Objective 6. Define, discuss, and differentiate
  between the concepts of cross-sectional studies
  and retrospective studies.

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Cross-Sectional Studies
Objective 6

• Cross-sectional studies (also known as prevalence
  or correlational studies) examine relationships
  between potential causal factors and disease at a
  point in time.

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Retrospective Studies
Objective 6

• Retrospective (case control) studies compare a
  group of individuals known to have a disease with
  a similar group of individuals who do not have
  the disease to determine whether the diseased
  group differs from the non-diseased group in its
  exposure to a specific factor or characteristic.
  Data collection extends back in time to determine
  previous exposure or risk factors.

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Objectives Epidemiology

• Objective 1. Define and discuss the following
  terms compare and contrast the following methods
  and concepts of epidemiology related to
  community health
• 1. descriptive epidemiology
• 2. analytic epidemiology
• Objective 2. Define the following epidemiological
  concepts, including their identifying factors and
  interconnection in epidemiology and the disease
  process
• 1. epidemiological triangle
• a. agent
• b. host
• c. environment
• Objective 3. Define and differentiate, and be
  able to calculate, as well as discuss the
  implication of the following epidemiological
  rates
• 1. attack rate
• 2. incidence rate
• 3. prevalence rate
• 4. age-adjusted rate
• 5. proportionate mortality rate
• Objective 4. Define and discuss the concepts of
  risk and risk factors as the two terms relate to
  the epidemiological process
• Objective 5. Define, discuss, and differentiate
  the concepts of screening and surveillance as
  they relate to the epidemiological process
• Objective 6. Define, discuss, and differentiate
  between the concepts of cross-sectional studies
  and retrospective studies.