Incidence And Prevalence
- 1. Incidence and Prevalence Measures of Disease Frequency Ayman Abou Mehrem, MD, CABP Neonatology Academic Day March 24, 2010
- 2. Objectives Importance of Measures of Disease Frequency Prevalence Incidence Relationship Between Prevalence and Incidence Stratification of Disease Frequency by Person, Place, and Time
- 3. 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.
- 4. 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
- 5. 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?
- 6. Prevalence Prevalence measures help to describe the current burden of a disease in a population in order to facilitate planning and resource allocation
- 7. Incidence The number of new cases of disease that develop over time
- 8. 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
- 9. 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
- 10. Incidence Diagram of individual risk time and disease status
- 11. Incidence Incidence measures help to provide clues as to the cause or development of a disease
- 12. Relationship Between Prevalence and Incidence
- 13. Stratification Refers to the process of separating analysis by subgroups. Stratification can be by: Personal Characteristics: age, race/ethnicity, sex Geography Time periods
- 14. 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