Chapter 5 Morbidity Measures

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Chapter 5 Morbidity Measures

• Incidence
• Prevalence
• Attack Rate

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Incidence Rate
Number of new cases in a population
Over a period of time Rate
----------------------------------------- X
1,000 Number of people exposed to the risk
of developing the disease
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Incidence Examples

• Cases of URI
• Post-operative complications
• Food poisoning
• Re-admissions to hospital
• Nosocomial infections
• Cases of TB, STDs, etc

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Variables

• Dont forget Time, Place, and Person!
• Age
• Sex
• Race
• Occupation
• Geographic location

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Approaches to Incidence Measures

• Make sure N/D match up
• Cumulative rates -- used in longitudinal studies.
  People at risk D
• Force of Morbidity -- predicts the risk of a well
  person getting ill over a time period D
  population time element

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Risk Determination

• What is the population at risk?
• Risk ratio --ratio of two rates
• RR Probability of disease exposure/ Probability
  of a disease not yet exposed
• Relative Risk -- studies the association between
  populations and diseases
• Good example table 5.1
  

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Risk Factors
Important for improving the health of a
population Examples life style, medical
history, work you do Fundamentals of the health
promotion and wellness movement
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Attack Rates
Used for situations like food poisonings,
specific infectious outbreaks Crude attack
rate Attack rate Food specific attack rate
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Occupational Health
OSHA Measurements are made based on hours worked
Number of injuries x200,000 Rate
--------------------------------------
X 100 total hours worked by all
employees during time period
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Prevalence Rates
The number of cases present at a particular
time Number of cases Rate -------------------
-- X 1,000 Total population
Point and period prevalence rates are also used
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Epidemics

• Common Source the epidemic comes from one source
• Propagated Source Epidemic Comes from multiple
  places
• (figures 5.4 and 5.5)

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Odds Ratios
Use of 2x2 tables Figure 5.6 Illustrates who was
exposed and who got sick. Illustrates
probabilities
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Formal Sources

• Clinical Records
• Managed Care Records and data
• Registries
• Surveys of disease and Health Status