National Growth and Health Study (NGHS)

BACKGROUND:

Although not all scientists agree that obesity is an independent risk factor for coronary heart disease, it may be a strong univariate predictor of coronary heart disease, and impacts on coronary heart disease through at least some of its relationships with other risk factors: positive association with blood pressure, inverse association with high density lipoprotein cholesterol (HDLC), positive association with triglyceride and very low density lipoprotein cholesterol (VLDLC), and a positive association with hyperglycemia and diabetes. A number of these have been shown to be major coronary heart disease risk factors. Prevention of obesity, or weight reduction towards desirable body weight may reduce the incidence of coronary heart disease and some of its risk factors. There is evidence to suggest that once obesity begins and/or advances in childhood, it will track into adulthood, with a reasonably high level of certainty. Obesity becomes progressively more difficult to treat with maturation to adulthood. Thus, better understanding of the pathophysiology of obesity in late childhood and early adolescence should, in the long-run, provide the basis for effective prevention or intervention programs in order to have a long-range impact upon the consequence of obesity. The age group 9 and 10 at entry has been selected to assure that many of the individuals are enrolled prior to puberty, and followed through this transition period when obesity becomes more apparent among Black adolescent females than among white.

Support for this research grew out of recommendations made at the Working Conference on Coronary Heart Disease in Black Populations held in September 1983 and sponsored by the NHLBI. The group recommended this research to identify the physiological and/or behavioral factors which contribute to obesity in Black females. In addition, the 1981 Report of the Working Group on Arteriosclerosis of the NHLBI stated that research is needed to characterize the behaviors that create and maintain caloric imbalance. The initiative was approved by the September 1984 National Heart, Lung, and Blood Advisory Council and the Request for Proposals was released in November 1984.

The NGHS I was initiated in 1985 as a contract-supported program with three field centers and a coordinating center. Annual exams were conducted at baseline and through the years of follow-up. The study was renewed by means of the cooperative agreement mechanism in 1992 as the NGHS II to permit two additional years of follow-up exams. The study was again renewed in 1994 as NGHS III to continue annual examinations.

DESIGN NARRATIVE:

In this longitudinal study, there were a baseline examination and annual examinations. Data collected included: physical examination; anthropometric measurements; dietary information including food pattern and nutrient intake; physical activity; lipid, lipoprotein, and apolipoprotein profiles; family socioeconomic status; and psychosocial information. The study was renewed twice to continue the longitudinal investigation until the subjects reached the age of 19 to 20. Following the girls until that age allowed the documentation of the transition in risk factors when Black girls no longer have a cardiovascular risk advantage and to study the factors surrounding the transition. The longer follow-up also allowed for studies on the influence of smoking on body weight and the relationship of adolescent pregnancy to subsequent adiposity development, body fat patterning, blood pressure, and blood lipids.