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RESEARCH PRODUCT

Epidemiology and Classification of Strokes

subject

description

Epidemiology concerns the occurrence and distribution of diseases in the population. By prevalence is meant the number of cases of the disease at a particular moment in a given group of persons, for example, in the entire population of a certain territory or in a clearly demarcated population group. Incidence refers to the number of new cases of the disease occurring in a population in a particular period of time. Figures on prevalence and incidence are meaningful only if the given disease is unequivocally defined. If the definition is too specific, many cases are not included (false-negative cases), whereas too broad a definition leads to many false-positive identifications (Table 3.1). Disease mortality indicates the number of patients who die of the disease in a particular period of time (e.g., within a year). Since only a proportion of patients with cerebrovascular diseases die in the short term (early mortality), mortality data represent only an approximate estimate of incidence.