LOS ANGELES – Mounting evidence indicates that obesity in childhood and adolescence increases the risk for future cardiovascular disease (CVD), according to .
“Some of this increased risk is related to the high level of tracking of obesity from childhood to adolescence to adulthood,” Dr. Daniels, who chairs the department of pediatrics at the University of Colorado, Aurora, said at the World Congress on Insulin Resistance, Diabetes & Cardiovascular Disease. “But I think it’s also clear that childhood obesity is associated with risk factors for adult CVD, including hypertension, dyslipidemia, and type 2 diabetes. There’s a combination of things going on over the life course.”
Numerous studies have demonstrated a dose-response relationship between increased weight and all-cause mortality in cardiovascular disease for men and women. This operates through a variety of mechanisms, Dr. Daniels said, including hypertension, dyslipidemia, left ventricular hypertrophy, vascular inflammation, type 2 diabetes, and obstructive sleep apnea. “While overt cardiovascular disease does not occur in children, many of the mechanisms recognized in adults are also present in children and adolescents,” he said. “The trends for increasing prevalence and severity of obesity in children and the comorbid conditions associated with obesity are worrisome.”
The current prevalence of obesity in children and adolescents stands at about 18%, according to the latest National Health and Nutrition Examination Survey. However, the prevalence of severe obesity in youth aged 2-19 years has been increasing “fairly dramatically,” and now stands at 9% among girls and 8% among boys. Hispanics and non-Hispanic blacks are disproportionately affected. That may turn out to be important in terms of the future, Dr. Daniels said, because according to simulation models, childhood obesity and overweight will continue to be a major public health problem in the future (
Direct evidence is also beginning to emerge of a link between obesity in youth and adult cardiovascular disease. The factors in childhood that predict adult obesity include a higher level of body mass index, obesity present at an older age (adolescence vs. childhood), and the presence of obesity in parents, which reflects both genes and environment. Researchers led by Paul W. Franks, PhD, evaluated 4,857 American Indian children without diabetes who were born between 1945 and 1984 and followed them for death before age 55 (They assessed whether BMI, glucose tolerance, blood pressure, and cholesterol levels predicted premature death. There were 166 deaths from endogenous causes (3.4%) over a median follow-up of 24 years. Factors significantly associated with mortality included obesity (incident rate ratio 2.30), glucose tolerance (IRR 1.73), and hypertension (IRR 1.57).
In a separate analysis, researchers investigated the long-term effects of childhood weight on coronary heart disease (CHD) by studying 276,835 Danish schoolchildren for whom measurements of height and weight were available. They followed the individuals until they turned age 25 or older and used national registries to assess the fatal and nonfatal rates of CHD events (). The researchers found that higher BMI during childhood was associated with an increased risk of CVD in adulthood. However, they did not have data on BMI in adulthood, “which leaves open the question of whether childhood obesity works through adult obesity or also has an independent effect,” said Dr. Daniels, who is also pediatrician-in-chief at Children’s Hospital Colorado, Denver.
More recently, investigators studied 37,674 apparently healthy Israeli men from age 17 into adulthood (). Outcomes were coronary disease and diabetes. They found that an elevated BMI in adolescence is an independent risk factor for CVD in later life, while an elevated BMI in adulthood is an independent risk factor for both CVD and diabetes.
In the Fels Longitudinal Study, researchers enrolled 151 adults with metabolic syndrome and 154 without metabolic syndrome, with a mean age of 51 years (). “The idea was to look back at this cohort and see when the first differences might be observable between boys and girls who ultimately would develop metabolic syndrome and those who would not,” said Dr. Daniels, who was one of the study investigators. The first appearance of differences between adults with and without metabolic syndrome occurred at ages 8 and 13 for BMI and 6 and 13 for waist circumference in boys and girls, respectively. Odds ratios (ORs) for the metabolic syndrome in adulthood if BMI were elevated in childhood ranged from 1.4 to 1.9 in boys and from 0.8 to 2.8 in girls. At the same time, odds ratios for the metabolic syndrome in adulthood if waist circumference was elevated ranged from 2.5 to 31.4 in boys and 1.7 to 2.5 in girls.
“I think it’s safe to say that BMI and waist circumference may be important in predicting metabolic syndrome later in life and, ultimately, cardiovascular disease,” Dr. Daniels said.
He noted that as the prevalence and severity of obesity have increased in childhood, the prevalence of type 2 diabetes has also increased. “The time from diagnosis of diabetes to a CVD event is approximately 10-15 years in adults, and there is often a prediagnosis period of hyperglycemia, which ranges from 5-10 years,” Dr. Daniels said. “If the time course of CVD related to diabetes is the same for adolescents as adults, it is anticipated that adolescents with diabetes will begin having substantial CVD morbidity and mortality in their 30s or 40s. This will be a public health disaster. Emerging evidence from the TODAY study (Treatment Options for type 2 Diabetes in Adolescents and Youth) and other studies is emphasizing that at least some individuals with adolescent type 2 diabetes may have a more malignant form of disease than in adults. This is striking and important to consider as we look at how to prevent cardiovascular disease.”
Obesity in childhood is also associated with structural and functional abnormalities of the vasculature, according to studies that measure vascular structure via intima-media thickness of the carotid arteries, femoral arteries, abdominal aorta, or other arteries, as well as those that measure vascular stiffness via measures of intrinsic “visco-elastic” properties of the arterial wall. In one study of individuals aged 10-24 years, Dr. Daniels and his associates performed carotid ultrasound for carotid intima-media thickness on 182 patients who were lean, 136 who were obese, and 128 who had type 2 diabetes (). It demonstrated that youth with obesity and obesity-related type 2 diabetes have abnormalities in carotid thickness and stiffness that are only partially explained by traditional cardiovascular risk factors.
“We all know that obesity is very difficult to treat,” he concluded. “That’s true in children and adolescents as it is in adults. I think this argues for prevention of obesity, for us starting earlier, creating an optimal cardiovascular health situation that we can maintain during the course of childhood and adolescence. The payoff will be great if we can accomplish that.”
Dr. Daniels reported having no disclosures.