Differences in modifiable cardiovascular disease risk factors in Australian schoolchildren: the results of a nationwide survey

Two thousand four hundred schoolchildren ages 9, 12, and 15 years were randomly selected to participate in the Health and Fitness Survey of Australian Schoolchildren in 1985. Data on blood lipids, aerobic fitness, blood pressure, and obesity were obtained through physical measurement. Information on socioeconomic status and ethnic origin was collected via questionnaire. Serum total cholesterol and low and high-density lipoprotein cholesterol were lowest in the oldest age group. Girls had significantly higher serum lipid levels, the difference being greatest at 15 years. However, comparison of the total cholesterol/high-density lipoprotein cholesterol ratio showed a trend in the direction of decreasing risk with increasing age for girls, with the reverse being found in boys. Fifteen-year-old girls were also the fattest and least fit of all the children, but had significantly lower systolic and diastolic blood pressures than their male peers. Children of Asian ethnic origin had significantly lower systolic and diastolic blood pressures and a significantly higher mean high-density lipoprotein cholesterol and were less likely to be overweight compared with other ethnic groups. Children from Mediterranean/Middle-East countries were significantly fatter and had a higher mean diastolic blood pressure than the other ethnic groups. These differences were detectable at age 9 years. Children from lower socioeconomic backgrounds were fatter and had a significantly lower mean high-density lipoprotein cholesterol and higher mean serum triglyceride levels. As with ethnic origin, these differences were detectable at age 9 years. The results demonstrate that age, sex, ethnic origin, and socioeconomic status can be used as variables to describe mean differences in the levels of cardiovascular risk factors in the national population of children. As some elevations in risk factors appear to be present in the youngest age group and these levels correlate with fatty streak and fibrous plaque formation in young adulthood, preventive programs should aim at intervention prior to puberty.