Study Sample

CARDIA, a longitudinal study of cardiometabolic disease risk over adulthood, began in 1985–1986 with 5115 black and white adults aged 18 to 30 years recruited from 4 metropolitan areas (Birmingham, AL; Chicago, IL; Minneapolis, MN; and Oakland, CA).10 There have been 7 follow‐up examinations (years 2, 5, 7, 10, 15, 20, and 25) with the majority of survivors participating (91%, 86%, 81%, 79%, 74%, 72%, and 72%, respectively). CARDIA was approved by institutional review boards of each field center; each study participant provided informed written consent.

The 10‐year study period for the present analysis was 2000–2001 through 2010–2011, years 15, 20, and 25 of CARDIA. We randomly selected 860 individuals from within race‐sex strata of participants who attended the 2000–2001 exam; had CAC data from 2000 to 2001, 2005 to 2006, and 2010 to 2011; and complete covariate data from 2000 to 2001 (Figure). Of these participants, 817 had stored plasma for analysis (Figure). The analytic sample comprised 211 black men, 194 black women, 213 white men, and 199 white women, representing 30%, 19%, 23%, and 19% of the respective stratum‐specific 2000–2001 exam totals.

Flow diagram for eligibility and selection of study sample. CAC indicates coronary artery calcium; CARDIA, Coronary Artery Risk Development in Young Adults Study.