members completed four clinic examinations, conducted three years apart between 1987 and 1998. Follow-up for clinical events is annual. The CHS is a population-based NHLBI-funded cohort study of risk factors for cardiovascular disease in adults 65 years of age or older conducted at four field centers (10). The original predominantly white cohort of 5201 persons was recruited in 1989–1990 from random samples of the Medicare lists. An additional 687 African-Americans were enrolled in 1992–93. CHS participants completed standardized clinical examinations and questionnaires at study baseline and at nine annual follow-up visits. Follow-up for clinical events occurs every 6 months. The FHS began in 1948 with the recruitment of an original cohort of 5209 men and women who were 28 to 62 years of age at entry (11). Clinic examinations were performed approximately every two years. In 1971, a second generation of study participants, 5124 children and spouses of children of the original cohort were enrolled (12). With two exceptions, clinic examinations took place approximately every four years. Enrollment of the third generation cohort of 4095 children of offspring cohort participants began in 2002 (13). The RS is a prospective population-based cohort study comprising 7983 subjects aged 55 years or older.
