Lipid Research Clinics Population Studies

BACKGROUND: The Lipid Research Clinics program was created in 1971. The objectives were to evaluate the then current techniques for diagnosis of hyperlipoproteinemia; to acquire data across all age groups on the prevalence of different types of hyperlipoproteinemia, particularly genetically determined forms; to collect high quality data on the prevalence and incidence of atherosclerosis in different patterns of hyperlipoproteinemia; and to improve methods for detection, diagnosis, and medical care of coronary heart disease. The program consisted of the Population Studies and the Coronary Primary Prevention Trial. The coronary primary prevention trial is described under Clinical Trials in the database. As a result of the establishment of the U.S.-U.S.S.R. Joint Program in Cardiovascular Diseases in 1972, lipid research clinics were established in Moscow and Leningrad in 1974. The U.S.S.R. component of this collaborative research consisted of two Prevalence Studies and a Follow-up Study, all of which closely followed the U.S. Lipid Research Clinics Prevalence Study protocol. DESIGN NARRATIVE: Prevalence Study: The Prevalence Study was initiated in 1972 to determine the prevalence of different types of dyslipoproteinemias at ten North American Lipid Research Clinics. The Prevalence Study consisted of two screens designated as Visit 1 and Visit 2, and was conducted according to a standardized protocol in well-defined target populations. Data collection began in 1972 and ended in 1976. The median time between the two screens was 96 days. The objectives of Visit 1 were: to provide estimates of the prevalence of dyslipidemia in specified populations; to investigate the distribution of cholesterol and triglyceride; and to select participants for Visit 2. A total of 60,502 eligible participants were screened at visit 1. A 15 percent random sample (N=9,107) of all Visit 1 participants who had elevated lipids (N=6,882) or were taking lipid-altering medication (N=346) were asked to return for the Lipid Research Clinics Population Studies Visit 2 screen. The three groups of 16,335 participants represented approximately 25 percent of all subject screened at Visit 1. The objectives of Visit 2 were: to identify participants with primary or secondary dyslipoproteinemia; to determine the prevalence of lipid and lipoprotein patterns and their associations with coronary heart disease, other vascular diseases, and other risk factors for coronary heart disease; and to determine the relationships between lipids and lipoprotein patterns and selected nutritional, physiologic, and sociodemographic variables such as education and occupation of head of household, smoking, blood pressure, height, weight, triceps skinfold, Quetelet index, and sex hormone usage by females. Visit 2 procedures included an interview, a physical examination, an ECG, clinical chemistries, and one-day dietary recall. Family Study: The Family Study provided data on the relationship of familial and genetic attributes to plasma lipids and lipoproteins. A sample of all participants in Visit 2 of the Prevalence Study was chosen to participate as probands. Basic demographic information was collected and plasma lipids and lipoproteins were measured on all first-degree relatives and probands. The Family Study was initiated in 1975 and data collection was completed in 1978. Follow-Up Study: The Follow-up Study, initiated in 1977, was designed to relate the baseline observation made in 1972-1976 to total and cause-specific mortality. The study assessed the risk factor status of plasma triglycerides, HDL cholesterol and exercise electrocardiography for cardiovascular disease mortality in general, and coronary heart disease in particular. Follow-up baseline measurements included lipid and other clinical chemistries, one-day dietary recalls, medication histories and physical examinations. Assessments were also made of the relationships of estrogen use in women to subsequent cardiovascular disease, coronary heart disease, and cancer mortality and of the relationships of lipids and lipoprotein levels to site-specific cancer, as well as the relationship of retinol levels to cancer mortality.