Am Fam Physician. 2006;73(10):1795-1798
Case Study
EH is a five-year-old boy seeing you for a routine well-child examination. His mother is concerned about his weight. He weighs 55 lb (25 kg), and his height is 42.5 in (108 cm). His body mass index (BMI) is 21.4 kg per m2, which places him in the 95th percentile for his age.
Case Study Questions
1. Which of the following reasons explain why BMI is the preferred measure for detecting overweight in children and adolescents?
A. Feasibility.
B. It distinguishes increased fat mass from increased muscle mass.
C. Reliability.
D. It tracks reasonably well from childhood and adolescence into young adulthood.
2. Which one of the following statements about childhood and adolescent overweight is correct?
A. Childhood overweight is associated with a higher prevalence of metabolic consequences and risk factors such as insulin resistance, elevated blood lipid levels, and increased blood pressure.
B. Most overweight children experience short-term medical complications.
C. The prevalence of childhood overweight decreases as age increases.
D. Treatment for overweight is more effective in adolescents.
E. Common conditions associated with childhood overweight include pseudotumor cerebri, steatohepatitis, and cholelithiasis.
3. Which one of the following statements best reflects the findings of the U.S. Preventive Services Task Force (USPSTF) about screening for childhood overweight?
A. There is good evidence of substantial harm from screening and treatment for overweight.
B. There is good evidence that treatment in the primary care setting leads to effective weight loss in children.
C. There is good evidence that routine BMI screening correctly identifies all overweight children and adolescents who will become overweight or obese adults.
D. There is good evidence that childhood BMI predicts adult morbidity.
E. There is fair evidence that overweight adolescents are at increased risk of becoming obese adults.
Answers
1. The correct answers are A, C, and D. The USPSTF found fair evidence that BMI is a reasonable measure for identifying children and adolescents who are overweight or are at risk of becoming overweight. BMI is calculated as weight in kilograms divided by height in meters squared. Being at risk for overweight is defined as having a BMI between the 85th and 94th percentile for age and sex, and overweight is defined as having a BMI at or above the 95th percentile for age and sex. BMI is the preferred measure for detecting overweight because of its feasibility and reliability. Single BMI measures also track reasonably well from childhood and adolescence (six to 18 years of age) into young adulthood, as evidenced by longitudinal studies and tracking with adult obesity measures. One disadvantage of using BMI is the inability to distinguish increased fat mass from increased fat-free mass.
2. The correct answer is A. Childhood overweight is associated with a higher prevalence of intermediate metabolic consequences and risk factors for adverse health outcomes, such as insulin resistance, elevated blood lipid levels, and increased blood pressure. Severe childhood overweight is associated with relatively rare, immediate morbidity from conditions such as slipped capital femoral epiphysis, sleep apnea, pseudotumor cerebri, steatohepatitis, and cholelithiasis. Although the childhood emergence of “adult” conditions (e.g., type 2 diabetes) represents an increasing morbidity burden for some overweight children, most will not experience medical consequences for decades. Furthermore, the direct health costs of childhood overweight can only be estimated, with the major impact likely to be felt in the next generation of adults.
National data that track BMI show an increasing proportion of overweight children and adolescents, as well as an increasing degree of overweight. Prevalence increases with age and is higher in racial and ethnic minorities than in non-Hispanic whites. There is insufficient evidence to show that counseling or other preventive interventions by primary care physicians and other specialists are effective.
3. The correct answer is E. The USPSTF found insufficient evidence of the harms of screening or of prevention and treatment interventions. The critical gap is insufficient evidence showing that counseling or other preventive interventions by primary care physicians or specialists are effective. The USPSTF found fair evidence that overweight adolescents and overweight children eight years and older are at increased risk of becoming obese adults; however, there is no evidence that routine screening with BMI correctly identifies all overweight children and adolescents who will become overweight or obese adults. The USPSTF did not find enough evidence to show that routine screening for overweight will identify children at risk for future adverse health outcomes, such as cardiovascular risks. Therefore, the USPSTF concluded that the evidence is insufficient to recommend for or against routine screening for overweight in children and adolescents as a means to prevent adverse health outcomes.
Childhood overweight is a significant public health issue. It is important for physicians to measure and monitor growth over time in all children and adolescents. Children who may warrant closer monitoring are overweight children who may be at increased risk of becoming overweight or obese adults: older children (after age 12 to 13 years, and particularly after sexual maturity); younger children (six to 12 years of age) and older children who are overweight (usually above the 95th percentile); and younger children with one or more obese parents.
editor's note: Current growth charts from the Centers for Disease Control and Prevention incorporate the BMI measurement. These charts are available online at http://www.cdc.gov/growthcharts and as an adjunct to this feature.
Reprinted from the National Center for Health Statistics in collaboration with the National Center for Chronic Disease Prevention and Health Promotion, 2000. Accessed online April 25, 2006, at:http://www.cdc.gov/growthcharts.
Reprinted from the National Center for Health Statistics in collaboration with the National Center for Chronic Disease Prevention and Health Promotion, 2000. Accessed online April 25, 2006, at:http://www.cdc.gov/growthcharts.