Am Fam Physician. 2006;73(1):115-119
This statement summarizes the U.S. Preventive Services Task Force (USPSTF) recommendations on screening and interventions for overweight in children and adolescents and the supporting scientific evidence, and it updates the 1996 recommendations contained in the Guide to Clinical Preventive Services, 2nd ed.1 Explanations of the ratings and of the strength of overall evidence are given in Tables 1 and 2, respectively. The complete information on which this statement is based, including evidence tables and references, is included in the summary of evidence2 and evidence synthesis3 on this topic, available on the USPSTF Web site athttp://www.uspreventiveservicestaskforce.org. The recommendation is also posted on the Web site of the National Guideline Clearinghouse athttp://www.guideline.gov.
Summary of Recommendation
The USPSTF concludes 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.I recommendation.
Approximately 15 percent of children and adolescents six to 19 years of age are overweight and are at risk of diabetes, elevated blood lipids, increased blood pressure, and their sequelae, as well as slipped capital femoral epiphysis, steatohepatitis, sleep apnea, and psychosocial problems. The USPSTF found fair evidence that body mass index (BMI) is a reasonable measure for identifying children and adolescents who are overweight or are at risk of becoming overweight. There is fair evidence that overweight adolescents and children eight years of age and older are at increased risk for becoming obese adults. The USPSTF found insufficient evidence for the effectiveness of behavioral counseling or other preventive interventions with overweight children and adolescents that can be conducted in primary care settings or to which primary care physicians can make referrals. There is insufficient evidence to ascertain the magnitude of the potential harms of screening or prevention and treatment interventions. The USPSTF was, therefore, unable to determine the balance between potential benefits and harms for the routine screening of children and adolescents for overweight.
|The USPSTF grades its recommendations according to one of five classifications (A, B, C, D, or I) reflecting the strength of evidence and magnitude of net benefit (benefits minus harms).|
|A.||The USPSTF strongly recommends that clinicians provide [the service] to eligible patients.The USPSTF found good evidence that [the service] improves important health outcomes and concludes that benefits substantially outweigh harms.|
|B.||The USPSTF recommends that clinicians provide [the service] to eligible patients.The USPSTF found at least fair evidence that [the service] improves important health outcomes and concludes that benefits outweigh harms.|
|C.||The USPSTF makes no recommendation for or against routine provision of [the service].The USPSTF found at least fair evidence that [the service] can improve health outcomes but concludes that the balance of benefits and harms is too close to justify a general recommendation.|
|D.||The USPSTF recommends against routinely providing [the service] to asymptomatic patients.The USPSTF found at least fair evidence that [the service] is ineffective or that harms outweigh benefits.|
|I.||The USPSTF concludes that the evidence is insufficient to recommend for or against routinely providing [the service].Evidence that [the service] is effective is lacking, of poor quality, or conflicting, and the balance of benefits and harms cannot be determined.|
• It is important to measure and monitor growth over time in all children as an indicator of health and development. The number of children and adolescents who are overweight has more than doubled since the early 1970s, with the prevalence of overweight (i.e., BMI at 95th percentile or higher for age and sex) in children six to 19 years of age now at approximately 15 percent. The conclusion that there is insufficient evidence to recommend for or against screening for overweight in children and adolescents reflects the paucity of good-quality evidence on the effectiveness of interventions for this problem in the clinical setting. There is little evidence for effective, family-based, or individual approaches for the treatment of overweight in children and adolescents in primary care settings. The Centers for Disease Control and Prevention’s (CDC’s) Guide to Community Preventive Services4 has identified effective population-based interventions that have been shown to increase physical activity, which may help reduce childhood overweight.
• BMI (calculated as weight in kilograms divided by height in meters squared) percentile for age and sex is the preferred measure for detecting overweight in children and adolescents because of its feasibility, reliability, and tracking with adult obesity measures.5 BMI values are CDC population-based references for comparison of growth distribution to those of a larger population. Being at risk for overweight is defined as a BMI between the 85th and 94th percentile for age and sex, and overweight is defined as a BMI at or above the 95th percentile for age and sex.6,7 Disadvantages of using BMI include the inability to distinguish increased fat mass from fat-free mass, and reference populations derived largely from non-Hispanic whites, potentially limiting its applicability to nonwhite populations. Indirect measures of body fat, such as skinfold thickness, bioelectrical impedance analysis, and waist-hip circumference, have potential for clinical practice, treatment, research, and longitudinal tracking, although there are limitations in measurement validity, reliability, and comparability between measures.
|The USPSTF grades the quality of the overall evidence for a service on a three-point scale (good, fair, or poor).|
|Good:||Evidence includes consistent results from well-designed, well-conducted studies in representative populations that directly assess effects on health outcomes.|
|Fair:||Evidence is sufficient to determine effects on health outcomes, but the strength of the evidence is limited by the number, quality, or consistency of the individual studies; generalizability to routine practice; or indirect nature of the evidence on health outcomes.|
|Poor:||Evidence is insufficient to assess the effects on health outcomes because of limited number or power of studies, important flaws in their design or conduct, gaps in the chain of evidence, or lack of information on important health outcomes.|
• 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, increased blood pressure, and impaired glucose tolerance. Severe childhood overweight is associated with immediate morbidity from conditions such as slipped capital femoral epiphysis, steatohepatitis, and sleep apnea. Medical conditions new to this age group, such as type 2 diabetes mellitus, represent “adult” morbidities that now are seen more commonly among overweight adolescents. For most overweight children, however, medical complications do not become clinically apparent for decades.
Overweight refers to increased body weight in relation to height when compared with an acceptable weight standard,8 and it can be related to health risks and problems in children and adolescents. National data that track BMI show an increasing proportion of overweight children and adolescents, as well as an increasing degree of overweight.9 From 1999 to 2000 the prevalence of overweight (i.e., BMI at the 95th percentile or higher for age and sex) for children two to 19 years of age ranged from 9.9 to 15.5 percent. Prevalence increases with age and is higher in racial-ethnic minorities than in non-Hispanic whites. For example, Mexican-American children are significantly more overweight (23.7 percent) than non-Hispanic white children (11.8 percent) beginning at six years of age.10 Representative national data are unavailable to reliably estimate the prevalence of overweight in Asian children and adolescents.
Severe childhood overweight is associated with relatively rare immediate morbidity from conditions such as pseudotumor cerebri, slipped capital femoral epiphysis, steatohepatitis, cholelithiasis, and sleep apnea.11,12 Perhaps the most significant morbidities for overweight children and adolescents are psychosocial.13 Overweight also is associated with a higher prevalence of intermediate metabolic consequences, such as insulin resistance, elevated blood lipid levels, increased blood pressure, and impaired glucose tolerance. These conditions, which often are asymptomatic, increase the long-term risk of developing diabetes and heart disease in adulthood and are associated with persistent obesity into adulthood. However, the recent emergence of medical conditions “new” to overweight children, such as type 2 diabetes mellitus, represents the increasing prevalence of more serious shorter-term morbidity.12,14
The USPSTF examined the evidence to determine the benefits and harms of screening and earlier treatment of overweight in children and adolescents in clinical settings for reducing childhood and adult morbidity and mortality. The USPSTF found no direct evidence that screening for overweight in children and adolescents improves age-appropriate behavioral or physiologic measures or health outcomes.
BMI is the most commonly used index of overweight and obesity in childhood and adolescence. Single BMI measures track reasonably well from childhood and adolescence (six to 18 years of age) into young adulthood (20 to 37 years of age), as evidenced by longitudinal studies showing low to moderate (r = 0.3 to 0.4) or moderate to high (r = 0.5 to 0.9) correlations between childhood BMI and adult BMI measures. Increased tracking (r ≥ 0.5) is seen in older children (after 12 to 13 years of age, and particularly after sexual maturity); in younger children (six to 12 years of age) and older children who are more overweight (usually above the 95th or 98th percentile); and in younger children with one or more obese parents. Sex differences in tracking are not consistent across ages or within age categories, and limited data are available to compare white children with black children.15–21
Several fair- to good-quality longitudinal studies18,22–27 have examined the risks associated with childhood overweight and various adult health outcomes, including mortality, morbidity, socioeconomic status, and cardiovascular risk factors. These data are useful in demonstrating health outcomes that may occur when childhood overweight persists into adulthood. However, few of these studies controlled for adult BMI, thereby limiting the independent predictive value of childhood weight measures. One good-quality, longitudinal study controlling for adult BMI eliminated the association of childhood BMI with adult cardiovascular risk factors.28
Insufficient evidence is available on the effectiveness of interventions for overweight children and adolescents that can be conducted in primary care settings or to which primary care physicians can make referrals. Most research has investigated intensive group and individual family-based behavioral counseling interventions conducted by specialists in multidisciplinary obesity clinics involving small, selected groups of children eight to 12 years of age with variable completeness of follow-up. Twelve to 24 months after intensive treatment, these studies have shown 7 to 26 percent decreases in the mean percentage of overweight, which may be maintained or improved after five to 10 years in a subset of patients.29,30 One fair-quality randomized controlled trial31 (RCT) compared a reduced glycemic load diet with a conventional reduced-fat diet in adolescents in an intensive six-month educational and behavioral weight-control program. At 12 months, mean BMI decreased in the reduced glycemic load diet group (−1.2 +/− 0.7 kg per m2) and increased in the reduced-fat diet group (0.6 +/− 0.5 kg per m2; P < .02). A fair- to poor-quality RCT32 examined three physical activity interventions consisting of behavioral modification and general nutrition education components. Lifestyle education only was compared with lifestyle education plus moderate- or high-intensity physical activity. No differences were noted between the groups in their percentage of body fat or visceral adipose tissue. In a good-quality RCT33 with predominantly white adolescents, investigators compared an intervention group that received a single, computer-based, individually tailored counseling session followed by nine to 12 follow-up telephone calls with a control group that received a single, nontailored counseling session in a primary care setting. At seven months’ follow-up, those in the intervention group reported no more physical activity (kcal per kg per day), no less sedentary behavior (minutes per day), and no decrease in kilocalories or percentage of calories from fat than the control group. Changes in mean BMI z-scores were not different between groups (P < .09).
A fair-quality RCT29 compared weight loss differences of children eight to 12 years of age in an intervention group receiving a comprehensive, family-based behavior-change program plus an increased physical activity and decreased sedentary behavior component, with a control group receiving a comprehensive, family-based behavior-change program plus an increased physical activity component. At the 12-month follow-up, BMI decreased significantly more in boys in the intervention group (−1.76 ± 1.86 kg per m2) than in boys in the control group or girls in either the intervention or control group (P < .05). Girls in the intervention group showed a slight BMI increase from baseline, whereas girls in the control group showed a modest decrease in BMI (−0.27 ± 1.37 kg per m2).
A good-quality RCT34 compared BMI loss differences of adolescents in an intervention group treated with sibutramine (Meridia) with a control group treated with a placebo; both groups were in a comprehensive behavioral treatment program. Outcomes, limited to a 12-month follow-up, showed a significantly greater mean BMI loss (4.6 kg [10 lb, 2 oz]; 95% confidence interval [CI], 2.0 to 7.4) in the adolescents in the intervention group compared with those in the control group. Open-label medication that continued for six months resulted in weight maintenance in the intervention group and in weight loss in the control group, such that both groups had similar reductions (6.4 to 8.6 percent) from initial BMI at 12 months. A large number of patients in the control group had their sibutramine dosage reduced or discontinued because of adverse events. No acceptable-quality evidence is available for children or adolescents to be able to evaluate the effectiveness of surgical approaches in reducing overweight.
There is insufficient evidence on the harms of screening. Potential harms include labeling, induced self-managed dieting with negative sequelae, poor self-concept, poor health habits, disordered eating, or negative impact from parental concerns. These theoretic harms are inferred from studies of limited design. There also is insufficient evidence on the harms of interventions. Among four recent behavioral intervention trials, adverse effects were reported in one trial.33 Among patients who completed an intervention (37 of 44) in a good-quality RCT34 in a primary care setting, no problematic eating was detected in the adolescent participants after treatment. During the placebo-controlled phase of the sibutramine trial, 19 of 43 patients (44 percent) in the group receiving sibutramine had their dosage reduced or discontinued because of elevated blood pressure, pulse rate, or both. No other adverse events were reported.
The direct health costs of childhood overweight can only be estimated, particularly because the major impact is likely to be felt in the next generation of adults.11
One recent study estimated that hospital costs for overweight-related disorders in children and adolescents have more than tripled in the last two decades based on the doubling of children hospitalized for overweight-related asthma, diabetes, sleep apnea, and gallbladder disease and on lengthened hospital stays for overweight children.35
The sections on “Future Research” and “Recommendations of Other Groups” that are usually included in USPSTF recommendation statements are available in the complete recommendation and rationale statement on the USPSTF Web site athttp://www.ahrq.gov/clinic/uspstfix.htm. The complete statement also includes the list of USPSTF members at the time this recommendation was finalized.