Old at Heart
An increasing number of children are developing hypertension, a major risk factor for heart disease
“BEING YOUNG” is not a typical risk factor that comes to mind when thinking about dangerous heart conditions, nor do we expect the pediatrician to test for signs of such problems at an annual checkup. But in August, the American Academy of Pediatrics revised its guidelines for the screening, diagnosis and treatment of high blood pressure in youth, the first time these standards have been updated since 2004. The new recommendations simplified the diagnostic procedures for pediatric and adolescent high blood pressure, made the definition for hypertension more similar to adult guidelines and changed the term “prehypertension” to “elevated blood pressure.” The changes make it easier for doctors to spot a growing health threat that seems unbelievable: Children and adolescents are increasingly at risk for a heart condition that has always been tied to aging. “We think of someone with hypertension as being that 50-year-old man down the street, but it’s becoming more and more common even in young children,” says Dr. David Kaelber, a pediatric and internal medicine physician at Case Western Reserve University.
The shift hints at problems to come. Hypertension affects 3.5 percent of U.S. children, or more than 2.5 million people under 18. That number may seem puny compared with the one-third of U.S. adults with high blood pressure, but Kaelber says it is still worrisome. High blood pressure rates in children and adolescents have risen in line with higher rates of childhood obesity. Without intervention, children with high blood pressure are likely to become adults with high blood pressure, a risk factor for potentially fatal heart disease.
Thousands of studies have linked hypertension in adults to heart attack, stroke, angina and peripheral artery disease. This threat is why adequate screening in young people is so important, says Janet de Jesus, a program officer at the National Heart, Lung, and Blood Institute. “Kids definitely aren’t as healthy as they
used to be, and these guidelines are going to be a huge asset to the field.”
There are a variety of causes of high blood pressure in children and adults. Elevated blood lipids can form plaque deposits on arteries, making them narrower and stiffer, which can increase blood pressure. People with higher body weights have more blood, raising the amount of pressure on the walls of arteries. Smoking damages arteries and leads to inflammation. Kidney problems, obstructive sleep apnea and even medications and thyroid issues can all lead to hypertension.
But high blood pressure isn’t just a sign that something is wrong in the body—it’s a problem in and of itself. Hypertension further damages arteries, and the excess strain on the heart can cause that muscle to grow thicker, which can interfere with its ability to deliver blood, oxygen and nutrients to the body. This cascade of maladies makes hypertension one of the major risk factors for heart disease, along with obesity, high cholesterol, smoking, physical inactivity and diabetes.
The problem, according to Dr. Carissa Baker-Smith, an epidemiologist at the University of Maryland and the lead data scientist on the new American Academy of Pediatrics guidelines, is that many of these issues go undetected until disaster strikes. She points to several studies that provided the definitive evidence that although heart disease often may not become apparent until adulthood, its seeds are planted in childhood. A study called Pathobiological Determinants of Atherosclerosis in Youth in the 1990s and the ongoing Bogalusa Heart Study have measured the prevalence of narrowed and hardened arteries (atherosclerosis) in adolescents and young adults who died accidentally. Both studies show strong associations between atherosclerosis—a leading predictor of heart disease—and smoking, cholesterol levels and hypertension. “I really want people, especially parents, to understand that high blood pressure does occur in kids. We’re seeing adult disease in children,” Baker-smith says.
These results challenge the now-outdated notion that hypertension in kids was primarily the result of congenital conditions that affected the kidney and heart. Although genetics accounts for one-fifth of all high blood pressure cases in kids under 18, the remainder are “adult-style” hypertension issues, caused by a convergence of biological and environmental factors. Large epidemiological studies by the Centers for Disease Control and Prevention have documented a rise in systolic blood pressure and in diastolic blood pressure in children between 1988 and 2000, which suggests the increase in pediatric hypertension isn’t just the result of heightened awareness. Although adults have a single cutoff for potential blood pressure problems, determining that point is more complex for pediatricians because blood pressure in growing children varies by age, height and sex. Even when doctors were vigilant about screening for blood pressure issues in children, they struggled to interpret those results. “A lot of doctors were very confused,” says Dr. Suzanne Lazorick, a pediatrician and preventive medicine physician at Eastern Carolina University.
Kaelber puts it more starkly. “If you reviewed electronic medical records [for children], you could see blood pressures recorded, but the pediatrician never diagnosed hypertension,” he says. Physicians were unclear about what blood pressure level was too high, so the condition in children went unnoticed.
REVERSE ANY DAMAGE
These challenges led Kaelber and Dr. Joseph Flynn, a nephrologist at the University of Washington, to call for a revision of the 2004 guidelines they had authored. Baker-smith led a review of the 15,000-plus studies published since 2004 to create a rigorous base from which to distill findings. From there, they reviewed how well the current standards were working and what scientists were learning about high blood pressure in children and adolescents. The final document contains several major changes from previous recommendations, including how to measure blood pressure and how doctors diagnose hypertension, as well as the terminology to use.
Instead of screening for high blood pressure at every health care visit, the new guidelines say to screen only at annual well-child visits beginning at age 3. Many transient factors can affect blood pressure, including stress and caffeine, which could lead to inaccurate data and unnecessary testing. And doctors need several blood pressure readings to make a diagnosis of hypertension.
The panel also altered the transition from pediatric blood pressure tables to the 120/80 mmhg cutoff used for adults. The transition used to come at age 18, so a child could have abnormal blood pressure at the age of 17 years and 364 days and
then be fine the next day, Kaelber says. The new tables begin transitioning children to adult markers at age 13, depending on height and weight. This provides more consistency and will ease the transition to adult blood pressure standards.
To de Jesus, the importance of the new guidelines in ensuring adequate diagnosis and treatment of childhood hypertension can’t be overstated. When kids are young, they can completely reverse cardiovascular damage from hypertension or high cholesterol. By the time they reach adulthood, however, this ability diminishes.
Kaelber, Flynn, Baker-smith and colleagues also recalibrated the blood pressure tables to include only children with normal weights. Pediatricians decide if a child’s blood pressure is high by comparing it with those of a group of healthy children. But the growing numbers of children who are overweight and obese, two traits strongly linked to increased blood pressure, have skewed that benchmark data. Using only normal-weight children provides a better definition for a healthy blood pressure, Baker-smith says. The team also eliminated the need for echocardiograms (an ultrasound of the heart) unless the child requires medication, a change that reflects the growing number of hypertensive children without underlying congenital heart issues. For those with more severe hypertension in need of medication, echocardiograms have revealed cardiac complications more usually seen in adults, such as left ventricular hypertrophy, a thickening of the heart muscle.
Lastly, the guideline revision group changed the term “pre-hypertension,” used to indicate children whose blood pressure was a concern but who didn’t meet clinical definitions of hypertension, to “elevated blood pressure.” The new language is intended to sound an alarm. “Parents tend to hear pre-hypertension and think it’s not a problem because it’s before a disease, but that’s not what we’re trying to say,” Lazorick says.
The increasing reliance on ambulatory blood pressure monitoring devices could pose a challenge. Although these monitors provide increased accuracy, not all pediatricians have access to them. Ramping up the availability of ambulatory monitoring will be key to putting the recommendations into practice, Lazorick says.
Although some of these guidelines may seem more conservative—hypertension screening only at regular preventive care visits, reduced recommendations for echocardiogram—they actually decrease the potential for overdiagnosis of pediatric hypertension. “No one wants to give kids a diagnosis they don’t have or a treatment they don’t need,” Baker-smith says.
No standards can eliminate the risk of overdiagnosis. But given that first-line treatment for children with high blood pressure is dietary and physical activity changes, Baker-smith says this advice is low-risk and can benefit many children, even those without hypertension. Making these changes isn’t easy, especially in a culture awash in salty, fatty foods. By starting early and modeling healthy behaviors, de Jesus says, parents can teach their kids to make good decisions about food and exercise as they get older and have more autonomy. “Even adults struggle to choose water over soda or juice. How can we expect a 10-yearold to do that?” Lazorick asks.
But for children diagnosed with high blood pressure, having an adult disease requires growing up fast.
“KIDS DEFINITELY AREN’T AS HEALTHY AS THEY USED TO BE.”
+ GETTING PUMPED: The new guidelines call for pediatricians to start screening annually for high blood pressure beginning when a child is 3.