Incidence And Prevalence
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Incidence And Prevalence






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Incidence And Prevalence Incidence And Prevalence Presentation Transcript

  • Incidence and Prevalence Measures of Disease Frequency Ayman Abou Mehrem, MD, CABP Neonatology Academic Day March 24, 2010
  • Objectives
    • Importance of Measures of Disease Frequency
    • Prevalence
    • Incidence
    • Relationship Between Prevalence and Incidence
    • Stratification of Disease Frequency by Person, Place, and Time
  • Importance of Measures of Disease Frequency
    • Prior to any clinical trial:
    • How frequently does the disease occur?
    • Provide big picture information about a disease, framing public health questions and guiding resource allocation.
    • Describe the absolute risk of a disease.
    • Can be categorized, or stratified to gain insight into the pathogenesis (mechanism) of disease.
  • Prevalence
    • The amount of a disease at one particular point in time
    • The proportion of people who have the disease
    • Prevalence (%) =
      • ×100%
      • number of people with disease
      • _____________________________
      • number of people in the population
  • Prevalence
    • What is the prevalence of anxiety disorder among UM medical student?
    • What is the prevalence of cognitive disorders among school children born at < 34 wks GA in Manitoba?
  • Prevalence
    • Prevalence measures
    • help to describe the current burden of a disease in a population in order to facilitate planning and resource allocation
  • Incidence
    • The number of new cases of disease that develop over time
  • Incidence
    • Two definitions
      • Incidence proportion =
      • x 100%
      • Incidence rate (Incidence density) =
      • number of new cases of disease
      • _______________________________
      • population without disease at baseline
      • number of new cases of disease
      • _____________________________
      • person-time at risk
  • Incidence
    • What is the incidence of influenza infection among UM medical students (500 students) during a 3-month period from January through March 2009?
    • Time-at-Risk concept
  • Incidence
    • Diagram of individual risk time and disease status
  • Incidence
    • Incidence measures
    • help to provide clues as to the cause or development of a disease
  • Relationship Between Prevalence and Incidence
  • Stratification
    • Refers to the process of separating analysis by subgroups.
    • Stratification can be by:
      • Personal Characteristics: age, race/ethnicity, sex
      • Geography
      • Time periods
  • Reference
    • Epidemiology and Biostatistics:
    • An Introduction to Clinical Research
    • Bryan Kestenbaum; editors, K. Adeney, N. Weiss ; contributing author, Abigail B. Shoben
    • Springer Science+Business Media, LLC 2009