Hypertension risk greatly increased for children in top 15% of BMI

Children in the 85th percentile for body mass index (BMI) are at greatly elevated risk for high blood pressure and require regular monitoring as well as possible interventions, according to a study from the American Heart Association.

The study of 1,111 healthy Indiana school children—42% black, equally divided by sex (mean enrollment age, 10.2 years)—found that the adiposity effect on blood pressure was minimal until patients reached the overweight category, when it increased 4-fold. Researchers observed a similar effect on children younger than 10 years, those aged 11 to 14 years, and those older than 15 years. The group underwent 9,102 semiannual blood pressure and height/weight assessments during that time period (mean follow-up, 4.5 years).

“Higher blood pressure in childhood sets the stage for high blood pressure in adulthood,” said Wanzhu Tu, PhD, lead researcher and professor of biostatistics at Indiana University School of Medicine in Indianapolis. “Targeted interventions are needed for these children. Even small decreases in BMI could yield major health benefits.”

Researchers emphasized the importance of viewing overweight and obese children differently from their normal-weight cohort, even if they seem healthy. “The adiposity effects on blood pressure in children are not as simple as we thought,” Tu said.

He especially cautioned parents and pediatricians to monitor weight gain in already heavy children.

“If they see a dramatic weight gain in a child who already is overweight, they need to intervene with behavioral measures, such as dietary changes and increased physical activity, to improve overall health and minimize cardiovascular risk,” Tu said.

Researchers noted that leptin, the adipose tissue-derived hormone, together with heart rate, showed an almost identically patterned relationship to blood pressure as did BMI, suggesting a role of the hormone in the elevated blood pressure.

Obese girls at greater risk of high blood pressure

Although obesity does not help teens of either gender, the impact on girls is vastly greater than those of boys, according to a study.  The results from researchers at the University of California Merced were released on Friday and were presented during the American Physiological Society Conference.  The study may apply to the approximately 17 percent of U.S. children and adolescents between the ages of 2 and 19, a total of 12.5 million people. About 3 percent of children have high blood pressure, according to a 2007 study by the CDC.  Approximately 17 percent or 12.5 million children and adolescents age 2-19 are obese.  An estimated 3 percent of kids have high blood pressure according to a study in 2007 by the CDC.

In the study Dr. Rudy M. Ortiz, PhD, Associate Professor at School of Natural Sciences at UC Merced and his team, measured the systolic blood pressure and calculated the body mass index of 1,700 teenagers ages 13 through 17 during the school district health survey and physicals.

The researchers found that boys are 3.5 times more likely to develop elevated systolic blood pressure than non-obese boys.

Meanwhile, obese girls were 9 times more likely to develop elevated systolic blood pressure than non-obese girls.  Systolic blood pressure is the pressure in blood vessels when the heart beats; Body mass index helps calculate human body fat based on an individual’s height and weight.

"We were able to categorize the students in different ways, first based on BMI within each of the three blood pressure categories. Then we flipped that around and looked at each category of blood pressure for different weight categories said Dr. Ortiz."

Researchers found a connection between body mass index and systolic blood pressure. The effect of body mass index on systolic blood pressure is much greater when assessed by blood pressure.  "In each case, we are looking at SBP as the dependent variable, said Dr. Ortiz."

"The results do not bode well for obese teens later in life, especially for the girls,” said Dr. Ortiz.  "We know, for example, that obese adolescent females participate in 50 to 60 percent less physical activity than boys in the population surveyed."

Source: Medical Daily

Overweight children at risk of high blood pressure

Children who are overweight compared to their peers are nearly three times more likely to have high blood pressure, a new study shows.  The study, published in the journal Hypertension, followed 1,111 school-aged children in Indiana for an average of four years.  Twice each year, researchers visited schools to take blood pressure measurements and record the kids’ heights and weights.

About 40% of the children in the study were above the 85th percentile on growth charts for their height and weight. When children are above the 85th percentile, doctors consider them to be overweight.  Among the overweight kids, 14% had blood pressure that was higher than normal, while only 5% of normal-weight kids had elevated blood pressure.

The study also found that extra pounds are especially dangerous for kids who are already big.

"For an overweight and obese child, if you increase your BMI percentile a little bit, that would increase your blood pressure strongly,"says researcher Wanzhu Tu, PhD. Tu is a research scientist at Regenstrief Institute and professor of biostatistics at Indiana University School of Medicine, both in Indianapolis.  "In the same way," Tu says, for just a little bit of weight loss "you could benefit greatly in terms of blood pressure."

The risks of overweight were the same, regardless of the child’s sex or race. About 42% of the kids in the study were black.

Pediatricians say the study is wake-up call.  "We’ve tended to look at the overweight category as a lower-risk category," says Stephen R. Daniels, MD, PhD, chairman of the department of pediatrics at the University of Colorado School of Medicine in Denver. He was not involved in the research.  "This suggests to me that we really need to worry about kids who are in that overweight category," says Daniels, who is also pediatrician-in-chief at Colorado Children’s Hospital.

Other experts say the findings are concerning because having high blood pressure has been shown to set kids up for health complications.  Not only are children with high blood pressure much more likely to turn into adults who have high blood pressure, but newer studies have shown that kids can get the same kinds of organ damage -- to the heart, blood vessels, and kidneys -- that doctors once thought was only a problem for adults with the condition.

One study even found that kids with high blood pressure have subtle changes in the brain area that controls attention, problem solving, and working memory.  "For physicians, we have to take much more seriously this concept of the childhood origins of adult diseases and look beyond the weight and beyond the blood pressure level because we’re finding more evidence, subtle evidence, of injury," says Bonita Falkner, MD, professor of medicine and pediatrics at Thomas Jefferson University in Philadelphia.

"So it’s not going to be a risk that’s going to be in the future. It’s a risk that’s now," says Falkner, who wrote an editorial on the study, but was not involved in the research.

"It jacks up the concern about preventing childhood obesity and also not waiting until they are obese.  Even overweight can be problematic for children."

Source: WebMD/Hypertension