Lifetime prevalence rate

Lifetime prevalence (LTP) is the number of individuals in a statistical population that at some point in their life (up to the time of assessment) have experienced a "case" (e.g., a disorder), compared to the total number of individuals (i.e. it is expressed as a ratio or percentage).

Often, a 12-month prevalence (or some other type of "period prevalence") is used in conjunction with lifetime prevalence. There is also point prevalence, the prevalence of disorder at a more specific (a month or less) point in time. There is also a related figure lifetime morbid risk - the theoretical prevalence at any point in life for anyone, regardless of time of assessment. (example: Synopsis of article on "How Prevalent Is Schizophrenia?" from Public Library of Science)