SHEEP - the Stockholm Heart Epidemiology Program
SHEEP - The Stockholm Heart Epidemiology Program) is a population based case-referent study of risk factors for first episode of acute myocardial infarction.
Material and Methods
The Sheep study base comprised all Swedish citizens resident in the Stockholm county 1992-1994 who were 45-70 years of age and were free of previous clinically diagnosed myocardial infarction. Male cases were identified during a two-year period (1992-1993) and female cases during three years (1992-1994). Through October 1992, the study base included the ages 45-65 years; from November 1 1992 and onwards, the age span was 45-70 years. Fatal as well as non-fatal cases were included. One referent per case was randomly selected from the study base -after stratification for sex, age, and hospital catchment area.
Exposure information was collected by a questionnaire and a health examination including blood sampling. A large number of potential risk factors were included in the questionnaire items and comprised occupational, social, as well as life style or individual factors.
A total of 5452 subjects were included in SHEEP: 2246 cases and 3206 referents. The response rate was higher among men than among women. Exposure information based on both the questionnaire and biological data from the health examination was available for 78% of the male and 67% of the female non-fatal cases; the corresponding figures for their referents were 68% and 64%.