Childhood obesity study focuses on risk assessment, prevention

MIT Medical Pediatrics Service chief Jocelyn Joseph, M.P.H., M.D., and nurse practitioner Pat Bartels, A.P.R.N., B.C., know the statistics as well as anyone-the proportion of overweight children more than doubling in the last 25 years, the rate in adolescents tripling. Even so, when MIT Medical's Pediatrics Service agreed to participate in a collaborative study to collect data on the incidence and treatment of childhood obesity, neither clinician expected much effect on the way they practiced medicine.

"We tend to think of the MIT community as quite different from the general population," Bartels notes. "Parents of the children in our practice are very intelligent, very well read, and generally quite well informed about health and nutrition. We didn't expect to find many overweight or at-risk-for-overweight children in our practice. Maybe four or five percent, I thought. That turned out to be an underestimate."

Going by the numbers

The "Healthy Care for Healthy Kids" study, a joint project of the National Initiative for Children's Healthcare Quality and Blue Cross Blue Shield of Massachusetts, aims to reduce the prevalence of childhood obesity by identifying children who are overweight or at risk of becoming overweight and by helping children and parents make healthy lifestyle changes. MIT Medical's Pediatrics Service started collecting baseline data on its patients last summer, having parents fill out a short nutrition and lifestyle questionnaire and calculating the "body mass index" measurement, or BMI, for each patient between the ages of two and 12.

The BMI number is a body-fat estimate obtained by using a standard formula to calculate a height-to-weight ratio. In adults, BMI alone is sufficient to establish weight status. But children's proportion of body fat changes with development and is different for boys and girls of the same age. So, for children and adolescents, weight status is determined by comparing BMI with age- and gender-specific percentile values.

"Based on BMI," Bartels says, "our early data indicates that about 10 percent of the children in our practice are overweight, meaning that they have BMI values at or above the 95th percentile for their age and sex. Another 20 to 30 percent are 'at risk' for overweight, meaning a BMI value between the 85th and 95th percentile."

In the past, clinicians would evaluate a child's risk of overweight by plotting height and weight measurements on separate percentile-for-age charts and calculating whether the two numbers were more than two standard deviations apart. "Because it simultaneously considers height and weight, the BMI number is more specific and accurate," Joseph explains. "And the BMI chart is a good tool. Parents can look at the chart with us to see how their child compares to others."

One step at a time

Intervention and patient education are based on a "5-2-1" message-at least five servings of fruits and vegetables daily, along with two hours or less of "screen time" (television, computer, or video games) and at least one hour of active play. "It's been good to engage parents in longer conversations about exercise, about TV watching and computer time, and about nutrition," Joseph says. "It's nice to see that parents take this seriously and want to do something about it."

But wanting to make changes and actually making those changes are two different things, notes parent Susan Haber, who, along with clinical assistant Phyllis Jordan-Gill, rounds out the four-member "Healthy Care" study committee. "I have two children," Haber explains. "My son can eat whatever he wants and not gain an ounce. Unfortunately, it's not that way for my daughter, my husband, and me." Haber sees her role on the committee as providing a consumer perspective. "I'm here to tell the clinicians how parents will perceive some of their suggestions," she says. "For example, when Dr. Joseph first showed me the recommendations-specifically, dessert only once a week and an hour of exercise every day-I felt overwhelmed. I worry that some parents will hear this message, think it's impossible, and give up without even trying."

Change can be difficult, Joseph agrees. "I try to get parents to start with small changes," she says, "to set some simple, achievable goals. I'll ask, 'How many juice boxes is your child drinking a week?' And then maybe we'll set a goal of drinking only two juice boxes a week instead of five and drinking more water."