Background:

Childhood and adolescent overweight and obesity are related to health risks, medical conditions, and an increased risk of adult obesity, with attendant impacts on morbidity and mortality. The prevalence of overweight has increased over the last 25 years among all American children and adolescents, but particularly among racial/ethnic minorities. The relatively greater increase in the upper body mass index (BMI) percentiles compared with the lower suggests that severity of overweight is increasing. Although obesity is the presumed condition impacting health, the use of the terms “at risk for overweight” and “overweight” are preferred when describing relative weight status based on age- and sex-specific BMI percentiles for children and adolescents, as these terms are more accurate and less pejorative.

Purpose:

The focus of this evidence synthesis is to examine the evidence for the benefits and harms of screening and earlier treatment of overweight in children and adolescents in clinical settings.

Data Sources:

We developed an analytic framework and seven key questions to represent the logical evidence connecting screening and weight control interventions with changes in overweight and behavioral, physiological, and health outcomes in childhood or adulthood. We searched the Cochrane Library from 1996 to April 2004. We searched MEDLINE®, PsycINFO, DARE, and CINAHL from 1966 to April 2004, using the Medical Subject Heading obesity and overweight and combining this term with predefined strategies to identify relevant English-language studies. We examined 2,162 abstracts related to screening, 312 related to screening harms, 949 related to treatment, and 864 related to treatment harms. We also contacted experts and checked bibliographies from review articles and selected trials. We found three recent, good-quality systematic reviews of interventions, one fair-to-good-quality systematic review relating screening measures to health outcomes, and a number of non-systematic, but comprehensive, review articles on screening, treatment, or other issues related to pediatric overweight. We relied on these as sources of relevant literature and, to a lesser extent, of synthesized information. When previous systematic reviews were incorporated in our results, we independently examined the individual studies to confirm or extend previous review findings. A bridge search between April 2004 and April 2005 did not identify any new intervention trials that would impact the findings of this report.

Study Selection:

We included fair-to-good quality research (according to U.S. Preventive Services Task Force [USPSTF] criteria) in children and adolescents aged 2–18 years in the following categories: (1) the most current large, population-based, or nationally representative surveys of the prevalence of overweight and obesity to represent age- and, sex-specific prevalence for racial/ethnic subgroups (Mexican Americans, non-Hispanic blacks, Native Americans, Asians/Pacific Islanders, non-Hispanic whites); (2) prospective cohort studies conducted in the United States with clinically relevant childhood weight measures and adult health outcomes, including obesity; (3) randomized controlled trials (RCTs) or controlled clinical trials of screening; (4) RCTs of pharmacological agents or behavioral counseling interventions conducted in the United States or similarly industrialized countries, with at least six months' follow-up, reporting changes in overweight status with or without intermediate outcomes, health outcomes, or harms; (4) RCTs, controlled clinical trials, or controlled cohort studies of bariatric surgeries; and (5) prospective cohort studies and controlled clinical intervention trials with at least three months' follow-up for possible harms of screening or intervention. To confirm inclusion/exclusion status, two reviewers examined all abstracts (or a random subset in the case of the screening search) and included articles.

Data Extraction:

One reviewer abstracted relevant information from each included article into standardized evidence tables, and a second reviewer checked key elements. Two reviewers quality graded each article using USPSTF criteria. Excluded articles were listed in tables.

Data Synthesis:

No trials of screening programs to identify and treat overweight in children and adolescents have been reported. BMI (weight in kilograms [kg] divided by height in meters squared) is the preferred clinical measure for overweight. Although BMI is a measure of relative weight rather than of adiposity, it is widely recommended for use in children and adolescents to determine overweight, and correlates as well or better with measures of body fat in children and adolescents than other clinically feasible measures. Based on BMI criteria for overweight (BMI at or above the 95^th percentile for age and sex), 10% of two- to five-year-olds and 16% of those six and older are overweight, with significantly higher prevalence in minority racial/ethnic and sex-specific subgroups beginning at age six. Age- and sex-specific BMI percentiles for use as references for U.S. children and adolescents (CDC 2000 growth charts) have been created from nationally representative datasets that primarily included black and non-Hispanic white children. The validity of BMI-based overweight categorization in racial/ethnic minorities with differences in body composition may be limited, since BMI measures can not differentiate between increased weight for height due to relatively greater fat-free mass (muscle, bone, fluids) and increased weight due to greater fat in either individuals or populations.

BMI measures in childhood track to adulthood moderately or very well, with better tracking seen after age 12 to 13 (particularly when this age represents achieving sexual maturity), or in younger children (aged 6–12) with one or more obese parents or whose own BMI is above the 95^th percentile. The risk of adult obesity in those with childhood overweight (BMI ≥ 95^th percentile) provides the best available evidence by which to judge the clinical validity of BMI as an overweight criterion in children and adolescents. The probability of adult obesity in overweight adolescents is highest for 16–18 year-old white males (0.77–0.8) and white females (0.66–0.68), with little data on other race-ethnic groups in this age group available.

Limited research is available on effective, generalizable interventions for overweight children and adolescents that can be conducted in primary care or to which primary care can make referrals. Most research has investigated intensive behavioral counseling interventions conducted by specialists with repeated contacts over 6 to 12 months, many using family-based comprehensive behavioral treatments. The largest single body of research addresses children aged 8–12 years. No current research is reported in children aged two-five. The number of studies addressing adolescents is small, but increasing. Overall, current trials are limited due to small—often-selective—samples; non-comparable interventions between trials; short-term (6 to 24 months) follow-up; reporting of overweight outcomes only with minimal reporting of health outcomes; and failing to report intention-to-treat analyses.

Harms of screening and labeling children as overweight or obese theoretically include induced self-managed dieting with its sequelae, poorer self-concept, poorer health habits, disordered eating, or negative impacts of parental concern. Harms are not well reported in behavioral intervention trials. Limited good-quality evidence is available on pharmacological approaches as an adjunct to comprehensive behavioral treatment in adolescents, and no reasonable-quality evidence is available on bariatric surgery outcomes in adolescents.

Conclusions:

BMI measurement to detect overweight in older adolescents could identify those at increased risk of developing adult obesity, and its consequent morbidities. Promising interventions to address overweight adolescents in clinical settings are beginning to be reported but are not yet proven to have clinically significant benefits; nor are they widely available. Screening for the purposes of overweight categorization in children under age 12 to 13 who are not clearly overweight may not provide reliable risk categorization for adult obesity. Theoretical harms may occur from overweight labeling or from induced individual and parental concern. Screening approaches are further compromised by the fact that there is little generalizable evidence for interventions that can be conducted in primary care or are widely available for primary care referral. Despite this, the fact that many trials report short- to medium-term modest improvements (approximately 10%–20% decrease in percent overweight or a few units' change in BMI) suggests that overweight improvements in children and adolescents are possible.

Experts have identified pragmatic clinical recommendations for lifestyle changes that could be applied to all children and adolescents regardless of risk. While monitoring growth and development in children and adolescents through BMI documentation at visits is prudent, care should be taken not to unnecessarily label children and adolescents as overweight or at risk for overweight until more is known about BMI as a risk factor, and effective interventions are available.