New Risk Factor for Heart Disease in Very Young Children
The results from the newest study in a continuum of research on childhood obesity as a risk factor for heart disease in later life provide another reason for pediatricians to begin measuring and monitoring BMI in children as young as 3 or 4 years old.
The study found that the new risk factor – called BMI rebound age – indicates that the earlier in young childhood that kids reach their lowest BMI and then begin to gain body mass, the greater the chance of having adverse changes in known cardiovascular risk factors, which can show up as early as age 7.
The study was conducted by Thomas R. Kimball, MD, a cardiologist at Cincinnati Children's Hospital Medical Center, and funded by the National Institutes of Health. It is believed to be the first study to examine the relationship of BMI rebound and cardiovascular risk factors in children, and it's the latest in a series of studies conducted by Dr. Kimball and colleagues at Cincinnati Children's that have been presented at major scientific meetings over the past two years, all leading to one inescapable conclusion: Measuring BMI is just as important in children as it is in adults.
That age is important because BMI rebound occurs between the ages of 4 and 7. At this time, body mass index reaches its lowest point and then begins to rise. The earlier that rebound occurs in a child, the greater the likelihood that by age 7, the child will have higher blood pressure and insulin levels, increased left ventricular mass and left atrial size, and other cardiovascular risk factors, according to Jennifer Jaworski, lead author of the study and a third-year medical student at the University of Cincinnati College of Medicine.
"There is a very clear picture here – and a clear roadmap for pediatricians to follow," said Dr. Kimball. "We have to use BMI as a marker to identify children at risk – and then when we identify those children, we have to take aggressive action to reduce the obesity that BMI reflects, so that we prevent an epidemic of heart disease in young adults in the next decades."
Dr. Kimball and his colleagues enrolled 308, 3-year-old children in the study. The children were divided into three groups:
- Early BMI rebound age (below the 25th percentile)
- Middle BMI rebound age (between the 25th and 75th percentiles)
- Late BMI rebound age (above the 75th percentile)
Every four months, the researchers measured the children's height and weight. At age 7, the researchers obtained echocardiograms to determine left ventricular mass and left atrial size and laboratory tests to determine other risk factors. For boys and girls, earlier age of BMI rebound was associated with negative cardiovascular changes including high blood pressure and elevated left ventricular mass which is known to be a major risk factor for heart disease in adults.
Girls had a slightly earlier BMI rebound than boys, putting them at a slightly higher risk because they started gaining weight earlier, according to Dr. Kimball. BMI rebound age for children in the 25th percentile was 4.4 years for boys and 4.2 years for girls. BMI rebound age for children in the 75th percentile was 6.6 years for boys and 5.7 years for girls.
