ABSTRACT
Prevalence studies are conducted in order to examine the prevalence of a particular condition at a certain point in time. Also referred to as cross-sectional studies, they frequently take the form of surveys. They are often conducted at local level, and are useful for investigating disease trends over time, as well as for health service planning. Although prevalence studies are sometimes used to investigate causality, other study designs such as cohort and case-control studies are generally more suitable. Prevalence studies are not very useful for examining diseases which have a short duration. They are comparatively quick and easy to carry out, and are useful for situations where no suitable routinely collected data are available. Methods for identifying subjects require careful consideration. Electoral rolls or health authority records are often used for this purpose. Potential biases should be identified and steps taken to minimise their effect.
