The researchers explained:
"The process of atherosclerosis begins during childhood and is associated with adverse serum lipid concentrations including high concentrations of low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), and triglycerides, and low concentrations of high-density lipoprotein cholesterol (HDL-C). Serum lipid concentrations in childhood are associated with serum lipid concentrations in adulthood. For more than 20 years, primary prevention of coronary heart disease has included strategies intended to improve overall serum lipid concentrations among youths."
In order to analyze the trends in serum lipid concentrations among children and teenagers in the United States, Brian K. Kit, M.D., M.P.H., of the Centers for Disease Control and Prevention, Hyattsville, Md., and colleagues examined data on 16,116 children and adolescents aged between 6 to 19 years old. The youths took part in the nationally representative National Health and Nutrition Examination Survey (NHANES) between 1988-1994, 1999-2002, and 2007-2010.
The researchers measured average serum total cholesterol (TC), non-HDL-C, HDL-C. Among participants aged 12 to 19, the team also measured LDL-C and geometric average triglyceride levels.
Trends in negative lipid levels were reported for TC levels of 200 mg/dL and greater, non-HDL-C levels of 145 mg/dL and greater, HDL-C levels of less than 40 mg/dL, LDL-C levels of 130 mg/dL and greater, and triglyceride levels of 130 mg/dL and greater.
The scientists discovered that amongst those ages 6 to 19 years between 1988-1994 and 2007-2010, there was a decrease in median serum TC from 165 mg/dL to 160 mg/dL and an rise in average serum HDL-C from 50.5 mg/dL to 52.2 mg/dL. In addition, there was a reduction in the average serum non-HDL-C levels during this period of time.
According to the researchers: "Generally, the sex-, age-, and race/ethnicity-specific trends for TC, HDL-C, and non-HDL-C were similar in direction to the overall trends and consistent with a favorable trend, although for each group, the magnitude was not the same and the trend was not always significant." Between 1988-1994 and 2007-2010, there was a reduction in incidence amongst those ages 6 to 19 years of increased TC from 11.3% to 8.1% and non-HDL-C from 13.6 % to 10%. Frequency of low HDL-C was 17.3% in 1988-1994 and 14.8% in 2007-2010, a nonsignificant reduction. Among teenagers, there had been a reduction in frequency of increased LDL-C and triglycerides between 1988-1994 and 2007-2010 and a reduction in average serum LDL-C from 95 mg/dL to 90 mg/dL and geometric average serum triglycerides from 82 mg/dL to 73 mg/dL.
According to the researchers in 2007-2010, 22% of children and teens had either a low HDL-C level or high non-HDL-C, which had been less than the 27.2% in 1988-1994.
In addition, the team discovered that age- and race/ethnicity-adjusted TC was 4.3 mg/dL lower for boys and 6.5 mg/dL lower for girls in 2007-2010 than in 1988-1994. Individuals who were non-Hispanic black or Mexican American, and also girls who were non-Hispanic white had a lower age-adjusted TC in 2007-2010 compared to 1988-1994. Age- and race/ethnicity- adjusted HDL-C was greater for boys and girls in 2007-2010 compared to 1988-1994.
The researchers explained:
"Between 1988-1994 and 2007-2010, a favorable trend in serum lipid concentrations was observed among youths in the United States but adverse lipid profiles continue to be observed among youths. For example, in 2007-2010, slightly more than 20 percent of children aged 9 to 11 years had either a low HDL-C or high non-HDL-C concentration, which, according to the most recent cardiovascular health guidelines for children and adolescents, indicates a need for additional clinical evaluation."
They conclude: "The recently released Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents provides recommendations for preventing the development of cardiovascular risk factors including optimizing nutrition and physical activity and reducing exposure to tobacco smoke.
Specific screening approaches, including universal screening at select ages and management of adverse lipid concentrations, have also been detailed in these recent guidelines for youths. Future research from longitudinal studies or mortality-linked data, including NHANES, may include examining clinical outcomes for cardiovascular disease, including cardiovascular mortality, based on lipid concentrations present during childhood."
In an associated report, Sarah D. de Ferranti, M.D., M.P.H., of Harvard Medical School and Boston Children's Hospital, Boston, explains:
"Further research is needed to investigate the hypothesized contributors to change in childhood and adolescent lipid levels. Better understanding is needed about dietary trends and physical activity during childhood, areas that were not explored in the study by Kit et al but could be assessed using NHANES data. However it seems clear that population-wide efforts to alter cardiovascular disease [CVD] risk have potential to influence health risks.
Examples of other interventions that could have positive population-level effects on health include taxation of carbonated beverages, improved access to water in schools and in the workplace, and environmental changes to promote daily physical activity. Improvements in child and adolescent lipid values over the past 2 decades are significant and may portend improved CVD outcomes for the future, but much work should be done to better understand the changes and to build upon them."
Written by Petra Rattue