Preteens with a high body mass index (BMI) have increased risk factors for coronary artery disease in adolescence, researchers found.
Those with a greater BMI between ages 9 and 12 were more likely to have high blood pressure, high LDL cholesterol and triglycerides, and insulin resistance at ages 15 or 16, Debbie Lawlor, MD, of the University of Bristol in England, and colleagues reported in BMJ.
"Childhood BMI alone adequately identifies those who will be at increased risk of adverse cardiovascular profiles in adolescence," they wrote.
A higher BMI in childhood has been associated with an increased risk of cardiovascular disease later in life. However, few studies have examined the change in adiposity between childhood and early adulthood with regard to cardiovascular risk factors.
So to assess these shorter-term effects, the researchers conducted a prospective cohort study of data from the Avon Longitudinal Study of Parents and Children, which included 5,235 children ages 9 to 12 at baseline.
All participants had their BMI, waist circumference, and fat mass assessed at baseline and again at ages 15 or 16.
Outcomes included systolic and diastolic blood pressure and concentrations of fasting glucose, insulin, triglycerides, and HDL and LDL cholesterol.
At baseline, a total of 18.5% of the children were overweight; 4.5% were obese.
The prevalence of cardiovascular risk factors at ages 15 and 16 ranged from 2.9% for high diastolic blood pressure and triglycerides, to 28.8% for high systolic blood pressure.
The researchers found that all three measures of adiposity were associated with increased factors in both boys and girls, although BMI appeared to be the most robust predictor.
In girls, a higher BMI at ages 9 to 12 was associated with an increased likelihood of the following risk factors at ages 15 and 16:
- High systolic blood pressure: OR 1.23, 95% CI 1.10 to 1.38
- High LDL levels: OR 1.19, 95% CI 1.03 to 1.38
- High triglycerides: OR 1.43, 95% CI 1.06 to 1.92
- Low HDL levels: OR 1.25, 95% CI 1.08 to 1.46
- High insulin concentrations: OR 1.45, 95% CI 1.22 to 1.73
The researchers found similar results in boys:
- High systolic blood pressure: OR 1.24, 95% CI 1.13 to 1.37
- High LDL levels: OR 1.30, 95% CI 1.07 to 1.59
- High triglycerides: OR 1.96, 95% CI 1.51 to 2.17
- Low HDL levels: OR 1.39, 95% CI 1.22 to 1.57
- High insulin concentrations: OR 1.84, 95% CI 1.56 to 2.17
Adding waist circumference or fat mass to models didn't increase the variation in cardiovascular risk factors that were already explained by BMI and confounders alone, the researchers said.
"Contrary to concerns about BMI not being a suitable measurement of adiposity in childhood, we found no difference in the magnitudes of prospective associations ... suggesting that with respect to identifying those with more adverse cardiovascular risk profiles, BMI is just as suitable as waist circumference or fat mass in children," they wrote.
The researchers also found that girls who were heavier at ages 9 to 12 but lost the weight by ages 15 to 16 had similar chances of cardiovascular risk factors to those who were normal weight at both ages.
In boys who were heavier at younger ages, these risk factors still existed later even if they lost weight, but were significantly smaller than those who remained heavy, the researchers said.
"Children who change from overweight to normal weight improve their cardiovascular profiles compared with those who remain overweight in childhood and adolescence," they wrote.
The researchers concluded that the findings imply that BMI is a suitable tool for identifying children at risk of future adverse cardiovascular events.
They noted that the study may be limited in its generalizability.
The study was supported by the National Institutes of Health and the National Institute of Diabetes and Digestive and Kidney Diseases.
The ALSPAC was supported by the Medical Research Council, the Wellcome Trust, and the Univeristy of Bristol.
The researchers reported no conflicts of interest.
- Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner