Cumulative incidence: Difference between revisions
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It may also be calculated by the [[incidence rate]] multiplied by duration. | It may also be calculated by the [[incidence rate]] multiplied by duration. | ||
''Basic equation:'' Cumulative Incidence = # new (incident) cases/total population at risk | |||
''Applied:'' CI = IR<sub>i</sub> * t<sub>i</sub> (where IR<sub>i</sub> is the incidence rate, t<sub>i</sub> is the specified time period) | |||
==References== | ==References== |
Revision as of 15:17, 21 December 2011
Overview
'Cumulative incidence (sometimes referred to as incidence proportion) is a measure of disease frequency which counts the proportion of a candidate population that becomes diseased/develops disease over a specified period of time. Cumulative incidence measures occurrence of new cases of disease. It involves the transition from one state to another, such as non-disease to diseased state (incidence of disease) or diseased to non-diseased (incidence of cure).
Specific forms of cumulative incidence include:
- Crude mortality rate: number of deaths due to any cause/100,000 population during a specified time period
- Infant mortality rate: number of infant deaths due to any cause/1,000 population during a specified time period
- Morbidity rate: number of illnesses due to any cause/1,000 population during a specified time period
- Live birth rate: number of live births/1,000 population or childbearing women during a specified time period
- Case fatality rate: number of deaths due to disease X/number of people with disease X during a specified time period
- Attack rate: number of new cases of disease/number population at risk at beginning of time period during specified time period
Calculating Cumulative Incidence
It may also be calculated by the incidence rate multiplied by duration.
Basic equation: Cumulative Incidence = # new (incident) cases/total population at risk Applied: CI = IRi * ti (where IRi is the incidence rate, ti is the specified time period)