period prevalence
The proportion of a population that has a psychiatric disorder during a specified time period, typically 12 months.
Full Definition
Period prevalence measures the proportion of individuals in a population who experience a psychiatric disorder during a defined time interval, most commonly 12 months (annual prevalence) or 30 days (month prevalence). This measure captures both individuals who had the disorder at the beginning of the period and those who developed it during the observation window. Period prevalence is particularly useful in psychiatric epidemiology because many mental health conditions are episodic, and point prevalence may underestimate the true burden of illness. It provides a more comprehensive picture of service needs and disease impact than point prevalence, while being more feasible to assess than lifetime prevalence in large-scale surveys.
Usage
Usage note: Always specify the exact time period (e.g., 12-month, 6-month) when reporting period prevalence.
In Context
- "The 12-month period prevalence of anxiety disorders was 18.1% in the national survey." — Epidemiological report
- "Period prevalence estimates inform resource allocation for mental health services planning." — Public health planning