In epidemiology, the term prevalence tells us about the number of particular events in the community. AIDS for example may be very prevalent (the total number with this syndrome) but the incidence (new cases) is going down each year.
The prevalence of a disease in a statistical population is defined as the total number of cases of the disease in the population at a given time, or the total number of cases in the population, divided by the number of individuals in the population.
Prevalence means extent, but in scientific English it means "proportion which is expressed as a percentage. Prevalence is distinct from incidence. Prevalence is a measurement of all individuals affected by the disease within a particular period of time. Incidence is a measurement of the number of new individuals who contract a disease during a particular period of time.
Lifetime prevalence is the number of individuals in a statistical population that at some point in their life have experienced a disorder, compared to the total number of individuals. A 12-month prevalence is used in conjunction with lifetime prevalence.
Point prevalence, the prevalence of disorder at a more specific point in time. Point prevalence means the prevalence, or number of cases, a snapshot of cases, at a certain point in time. The point in time could be any length, from an hour to a month. It is important to note that while point prevalence reflects the magnitude of health events; it may not be useful in finding causes for disease.
Incidence is a contrasting term to prevalence telling us the frequency of occurrence of some event during a particular time period.
Examples of prevalence studies:
How common is anorexia nervosa? A prevalence
AH Crisp, RL Palmer and RS Kalucy
The British Journal of Psychiatry 128: 549-554 (1976) 1976 The Royal College of Psychiatrists
During 1972-74 nine populations of schoolgirls were surveyed in respect of the occurrence of anorexia nervosa. As well as the current school year, previous years (going back variously 3-6 years) were also carefully studied within seven of the schools. In all such schools, the prevalence was one severe case in approximately every 200 girls. In those aged 16 and over it amounted to one severe case in about every 100 girls. Overall, these schools encountered one 'new' severe case in every 250 pupils aged 16 years and over.
Misuse of study drugs: prevalence,
consequences, and implications for policy
Steve Sussman, Mary Ann Pentz, Donna Spruijt-Metz and Toby Miller
Substance Abuse Treatment, Prevention, and Policy 2006, 1:15
Abstract: Background: Non-medical/illegal use of prescription stimulants popularly have been referred to as study drugs. Paper discusses the current prevalence and consequences of misuse of these drugs and implications of this information for drug policy.
Does Religion Increase the Prevalence and
Incidence of Obesity and Severe Obesity in Adulthood? - Clark, Krista. and
Paper presented at the annual meeting of the American Sociological Association
Abstract: This paper examines the relationships between religion and both obesity and severe obesity, which have increased in prevalence in the United States over the past two decades. Using longitudinal data from a national sample of adults, this study prospectively examines whether dimensions of religious life are associated with the development of obesity during eight years of follow-up. Logistic regression analyses reveal that high levels of religious media practice and affiliation with a Baptist denomination increased the risk of obesity and severe obesity. Although religious media practice was associated with greater risk of obesity, attendance at religious services did not influence the prevalence or incidence of obesity or severe obesity.