The Cardiovascular Health Study is a population-based, longitudinal study of risk factors for the development and progression of coronary heart disease and stroke in adults over the age of 65 years. Both risk factors established in middle-aged population and suspected risk factors are examined and include hypercholesterolemia, hypertension, glucose intolerance and diabetes, and cigarette smoking. Since atherosclerosis is prevalent in the elderly, the study focuses on factors thought to induce clinically overt disease. It does so in two ways: (1) It assesses the prediction of clinical disease from non-invasive measure of preclinical disease, such as carotid atherosclerosis, left ventricular impairment, and arrhythmias of episodes of myocardial ischemia. (2) Since cardiovascular events may occur in elderly people as a result of health or life circumstances which may have changed in the months preceding the event, the study contacts participants at frequent intervals to evaluate their status with respect to concurrent disease, social support networks, stressful life situations, diet, physical activity, and other risk factors. The study has three secondary objectives pertaining to the elderly populations: (1) to evaluate the factors associated with preclinical cardiovascular disease such as carotid atherosclerosis, left ventricular impairment and episodes of arrhythmia or myocardial ischemia; (2) to evaluate predictors of disability, institutionalization and mortality in participants who have coronary heart disease or stroke; and (3) to measure the utilization and impact of medical care services for coronary heart disease and stroke. Currently, risk associations are identified with clinical disease by the accumulation of events. Risk estimates are compared in subgroups of participants, such as women versus men, African-American versus Caucasian, those older versus younger than 75 years, or those with versus without prevalent clinical or subclinical disease. Risk estimates are compared in subtypes of disease, such as fatal versus non-fatal myocardial infarction, symptomatic versus silent myocardial ischemia, or fatal versus non-fatal stroke. Estimates are compared of longer-term (5-10 year) versus short-term (1-3 year) CVD risk. The study is also; determining whether presence or progression of subclinical disease (abnormalities detected non-invasively without signs or symptoms) are better predictors of clinical disease than traditional risk factors; identifying determinants of change in subclinical disease; identifying characteristics of subgroups at low risk for developing CVD (in whom preventive measures may be unnecessary). The primary objective of the Ultrasound Reading Center is to develop and implement a system to assess atherosclerosis in the carotid arteries using ultrasound. This involves (1) coordinating development of a protocol for ultrasound examinations at the field Centers and a method for evaluating extent of carotid atherosclerosis, (2) training ultrasound technicians of each Field Center, (3) interpreting all ultrasound examinations and (4) monitoring the ultrasound examinations at all field Centers. During the periods of data collection, the Ultrasound Reading Center shall have the responsibility of assessing within and between individual variation among technicians and codes.
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