Excess Body Mass Index- and Waist Circumference-Years and Incident Cardiovascular Disease: The CARDIA Study
Jared P. Reis, PhD1, Norrina Allen, PhD2, Erica P. Gunderson, PhD3, Joyce M. Lee, MD, MPH4, Cora E. Lewis, MD, MSPH5, Catherine M. Loria, PhD,1 Tiffany M. Powell-Wiley, MD, MPH6, Jamal S. Rana, MD, PhD3, Stephen Sidney, MD, MPH3, Gina Wei, MD, MPH1, Yuichiro Yano, MD2, Kiang Liu, PhD2
1Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, Bethesda, MD
2Department of Preventive Medicine, Northwestern University Feinberg School of Medicine,
Chicago, IL
3Division of Research, Kaiser Permanente Northern California, Oakland, CA
4Division of General Pediatrics, University of Michigan, Ann Arbor, MI
5Division of Preventive Medicine, Department of Medicine, University of Alabama at
Birmingham, Birmingham, AL
6Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute and Applied
Research Program, Division of Cancer Control & Population Studies, National Cancer Institute,
Bethesda, MD
Name and address for correspondence: Jared P. Reis, PhD, Division of Cardiovascular
Sciences, National Heart, Lung, and Blood Institute, 6701 Rockledge Dr, Suite 10186, Bethesda,
MD, 20892, (301) 435-1291, FAX: (301) 435-1291, email: [email protected] Other measurements
After a 5-minute rest, blood pressure was measured on the right arm of seated participants at three one-minute intervals using a Hawksley random zero sphygmomanometer
(WA Baum Company, Copaigue, NY) at baseline through year 15. At years 20 and 25, blood pressure was measured using a standard automated blood pressure measurement monitor
(OmROn model HEM907XL; Omron). A calibration study was performed, and values at years
20 and 25 were recalibrated to the random zero measurements, so that essentially no machine bias remained. Blood was drawn by venipuncture according to a standard protocol (1). Plasma total cholesterol, HDL cholesterol, and triglyceride concentrations were measured at all examinations by enzymatic methods at Northwest Lipids Research Laboratory (Seattle, WA).
HDL cholesterol was measured after dextran-magnesium precipitation. Glucose was assayed at baseline using the hexokinase ultraviolet method by American Bio-Science Laboratories (Van
Nuys, CA) and hexokinase coupled to glucose-6-phosphate dehydrogenase (Millipore, Inc,
Bellerica, MA) at years 7, 10, 15, 20 and 25. The insulin measurements were performed with the use of a radioimmunoassay (Linco Research, St Charles, MO) at baseline and years 7, 10, 15 and
20, and an Elecsys sandwich immunoassay (Roche Diagnostics Corporation, Indianapolis, IN) at year 25. Diabetes was determined based on a combination of measured fasting glucose levels
(≥7.0 mmol/l, ≥126 mg/dl) at baseline and years 7, 10, 15, 20, and 25; self-report of oral hypoglycemic medications or insulin (all examinations), a 2-hour postload glucose ≥11.1 mmol/l
(≥200 mg/dl) at years 10, 20, and 25; or a glycated hemoglobin A1c ≥6.5% at years 20 and 25 (2).
Standardized questionnaires were used to maintain consistency in the assessment of demographic (age, sex, race, and education) and behavioral (physical activity, cigarette smoking, and alcohol use) information across all CARDIA examination visits. Education was represented as maximum years of schooling. The CARDIA Physical Activity History questionnaire queried the amount of time per week spent in 13 categories of leisure, occupational, and household physical activities over the past 12 months (3). Total daily alcohol consumption was calculated from an interviewer-administered questionnaire. The validated, interviewer-administered quantitative CARDIA dietary history was used to estimate average energy intake over the past month at baseline and years 7 and 20 (4, 5). Briefly, the CARDIA dietary history asked individuals to report foods eaten, including beverages, during the previous month using about
100 header questions, such as “Do you eat meat?” followed by open-ended responses. The use of antihypertensive and lipid-lowering medication was assessed by self-report at each examination. References
1. Friedman GD, Cutter GR, Donahue RP, Hughes GH, Hulley SB, Jacobs DR, Jr., et al. CARDIA: study design, recruitment, and some characteristics of the examined subjects. Journal of clinical epidemiology. 1988;41(11):1105-16. 2. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2010 Jan;33 Suppl 1:S62-9. 3. Jacobs DR, Jr., Hahn LP, Haskell WL, Pirie P, Sidney S. Validity and reliability of short physical activity history: CARDIA and Minnesota Heart Health Program. J Cardiopulm Rehabil. 1989;9(11):448-59. 4. McDonald A, Van Horn L, Slattery M, Hilner J, Bragg C, Caan B, et al. The CARDIA dietary history: development, implementation, and evaluation. Journal of the American Dietetic Association. 1991 Sep;91(9):1104-12. 5. Liu K, Slattery M, Jacobs D, Jr., Cutter G, McDonald A, Van Horn L, et al. A study of the reliability and comparative validity of the cardia dietary history. Ethnicity & disease. 1994 Winter;4(1):15-27.