Prevalencemått

Prevalencemått, or prevalence measure, is a statistic used to quantify the proportion of a population that has a particular condition at a specific moment or during a defined interval. It reflects both the rate at which new cases occur (incidence) and the average duration of the condition, so high prevalence can result from high incidence, long duration, or both. Prevalencemått is commonly reported as a percentage or per 1,000 or 100,000 people.

Point prevalence refers to the proportion of people with the condition at a single point in time. Period prevalence covers a time interval, typically expressed as the number of people who have the condition at least once during the period divided by the population at risk during that period. Lifetime prevalence indicates the proportion who have ever had the condition by a certain age. In all cases, the choice of denominator and the case definition influence the measure.

Calculation relies on cross-sectional surveys, health records, or disease registries. Adjustments such as age standardization are often applied to enable fair comparisons across populations with different age structures. Interpretation should account for survival and migration, potential under- or over-ascertainment, and changes in diagnostic criteria. Prevalencemått informs public health planning, burden assessment, and resource allocation, and is frequently used alongside incidence and mortality metrics to describe the scale of health problems.