Prevalence
Say it: PREV-uh-luns
Prevalence is the share of a population living with a particular disease or condition, either at one point in time or across a set period.
Definition
What is prevalence?
Prevalence measures how widespread a disease or other condition is. It counts everyone who has the condition, both new and long-standing cases, and divides by the size of the population, giving a percentage or a figure such as cases per 100,000 people. It offers a snapshot of the burden a condition places on a community.
Epidemiologists distinguish several kinds. Point prevalence is the share of people affected on one particular date. Period prevalence is the share affected at any time during an interval, such as the past year, and lifetime prevalence is the share who have ever had the condition. Prevalence is usually measured with cross-sectional surveys of a population.
Prevalence depends both on incidence, the rate at which new cases appear, and on how long the condition lasts. A chronic condition such as diabetes can have a high prevalence even when new cases are few, because people live with it for years, while an illness that resolves quickly or is rapidly fatal keeps prevalence low. For this reason prevalence is most useful for planning health services for long-lasting conditions, while incidence is better for studying causes.
Word parts
Where does the word “prevalence” come from?
- pre-
- beforeLatin prae
- -val-
- be strong, be ableLatin valere, via praevalere, to prevail
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Related
Terms that go with it
- IncidenceIncidence is the number of new cases of a disease that arise in a population at risk during a specified period of time.
- EpidemiologyEpidemiology is the study of how often diseases and other health events occur in populations, what causes them and how they can be controlled.
- Public healthPublic health is the science and practice of preventing disease and injury and promoting health across whole communities rather than individual patients.
- Diabetes mellitusDiabetes mellitus is a chronic disease in which blood glucose stays too high because the body makes too little insulin or cannot use it well.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- CDC Principles of Epidemiology, Lesson 3 Section 2: Morbidity Frequency Measures
- NIMH: What is Prevalence?
- NCI Dictionary of Cancer Terms: prevalence
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