Change and fluctuation in body mass index (BMI; weight (kg)/height (m)(2)) may be associated differently with coronary artery calcification (CAC) than with carotid artery intima-media thickness (IMT). The authors analyzed data on 2,243 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, initially aged 18-30 years, who were examined every 2-5 years over a 20-year period (1985-2006). BMI at year 0 was associated positively and linearly with CAC at year 20; however, the association of BMI with year 20 CAC became progressively U-shaped in subsequent examinations (years 10, 15, and 20). To understand the deepening U shape, the authors modeled year 20 BMI and its history using 3 indices: year 0 BMI, linear slope of BMI during 20 years, and BMI fluctuation during 20 years. In models including these 3 terms, year 0 BMI was associated positively with CAC, as was BMI fluctuation. However, adjusted odds ratios across quintiles of BMI slope (vs. the lowest quintile) were 0.7, 0.4, 0.5, and 0.4 (P(trend) < 0.01), suggesting higher risk of CAC with weight loss, plateauing after moderate weight gain. In contrast, IMT was associated positively with BMI at all examinations and with 20-year BMI slope and was unassociated with BMI fluctuation. Surprisingly, CAC risk was higher with BMI loss and lower with BMI gain, whereas associations with IMT were as expected.
Available at: http://works.bepress.com/catarina_kiefe/185/