Obesity duration associated with subclinical predictor of coronary heart disease

By Bruce Sylvester – In a 3-decade study of adults recruited in the United States, researchers report positive correlations between durations of overall obesity and abdominal obesity and rates of coronary artery calcification, a subclinical predictor of coronary heart disease.

The findings were published in the July 17, 2013 issue of JAMA, the Journal of the American Medical Association.

“These findings suggest that the longer duration of exposure to excess adiposity as a result of the obesity epidemic and an earlier age at onset will have important implications on the future burden of coronary atherosclerosis and potentially on the rates of clinical cardiovascular disease in the United States,” the authors wrote.

As background, they noted that subclinical atherosclerosis, diagnosed by the presence of coronary artery calcification (CAC), is a progressive condition and is predictive of the development of coronary heart disease events. “With a doubling of obesity rates for adults and a tripling of rates for adolescents during the last 3 decades, younger individuals are experiencing a greater cumulative exposure to excess adiposity during their lifetime. However, few studies have determined the consequences of long-term obesity,” they said.

Jared P. Reis, Ph.D., of the (US) National Heart, Lung, and Blood Institute, Bethesda, Maryland, and colleagues enrolled 3,275 white and black adults 18 to 30 years of age in 1985-1986 in the Coronary Artery Risk Development in Young Adults (CARDIA) study. At baseline, no subject had overall obesity (BMI ≥30) or abdominal obesity (men; waist circumference [WC] >40.2 inches; women: >34.6 inches). Of all enrollees, 45.7 percent were black and 50.6 percent were women.

The subjects underwent computed tomography scanning looking for CAC during their 15-, 20-, and 25-year follow-up examinations. Durations of overall obesity and of abdominal obesity were calculated at years 2, 5, 7, 10, 15, 20, and 25.

The investigators reported that 40.4 percent of the subjects developed overall obesity and 41.0 percent developed abdominal obesity. Among those who became obese, average duration of overall obesity was 13.3 years and average duration of abdominal obesity was 12.2 years.

CAC appeared in 27.5 percent (n = 902) of the subjects. “Extensive CAC was present in 6.5 percent and 9.0 percent of those with more than 20 years of overall and abdominal obesity, respectively, compared with 5.7 percent and 5.3 percent of those who never developed overall or abdominal obesity, respectively,” the researchers reported.

CAC rates rose with longer duration of overall obesity and abdominal obesity. Approximately 25.2 percent and 27.7 percent of those with more than 20 years of overall and abdominal obesity, respectively, showed progression of CAC, compared with 20.2 percent and 19.5 percent of those with 0 years.

“In conclusion, in this study a longer duration of overall and abdominal obesity beginning in young adulthood was associated with CAC and its 10-year progression through middle age independent of the degree of adiposity,” the authors said.