Incidence
- Measures how many new cases of a condition occur in a population during a defined time window.
- Used to assess the burden of a condition and to identify trends over time.
- Informs public health responses and targeted interventions.
Definition
Section titled “Definition”Incidence refers to the frequency or rate at which a particular event or phenomenon occurs within a given population or group. It is a measure of the number of new cases of a particular condition or disease that occur within a specific time period.
Explanation
Section titled “Explanation”Incidence is quantified by counting new cases of an event (for example, a disease) that are diagnosed or reported in a defined population during a defined time interval. Time windows used to measure incidence can vary (for example, one week, one month, or one year). Tracking incidence over time shows whether the rate of new cases is increasing, decreasing, or stable, and this information is used to evaluate the burden of the condition on the population and to guide responses.
Examples
Section titled “Examples”Influenza among school-aged children
Section titled “Influenza among school-aged children”The incidence of influenza among school-aged children in a particular community during the winter months may be determined by counting the number of new cases of the illness that are reported over a specific time period, such as one week or one month.
New cancer cases in a population
Section titled “New cancer cases in a population”The rate of new cancer cases in a population is determined by counting the number of new cases of cancer that are diagnosed within a specific time period, such as one year. This information helps determine the overall burden of cancer and identify trends in cancer incidence over time.
New HIV infections in a population
Section titled “New HIV infections in a population”The rate of new HIV infections is determined by counting the number of new cases of HIV that are diagnosed within a specific time period, such as one year. Monitoring this incidence helps determine the overall burden of HIV and identify whether efforts to prevent the spread of the virus are succeeding or need strengthening.
Use cases
Section titled “Use cases”- Assessing the burden of a condition or disease on a population.
- Identifying trends in the occurrence of a condition over time.
- Guiding the development of targeted interventions and public health strategies.
Notes or pitfalls
Section titled “Notes or pitfalls”- An increasing incidence may indicate a need for further research and interventions to address underlying causes and prevent spread.
- A decreasing incidence may indicate that prevention or control efforts are working.
Related terms
Section titled “Related terms”- Burden (of disease)
- Trends (in disease occurrence)
- Interventions (public health actions)