Screening and interventions for childhood overweight: a summary of evidence for the US Preventive Services Task Force.

BACKGROUND: Childhood and adolescent overweight and obesity are related to health risks, medical conditions, and increased risk of adult obesity, with its attendant effects on morbidity and mortality rates. The prevalence of childhood overweight and obesity has more than doubled in the past 25 years. Purpose. This evidence synthesis examines the evidence for the benefits and harms of screening and early treatment of overweight among children and adolescents in clinical settings.

METHODS: We developed an analytic framework and 7 key questions representing the logical evidence connecting screening and weight control interventions with changes in overweight and behavioral, physiologic, 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. 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 with US Preventive Services Task Force criteria.

RESULTS: Although BMI is a measure of relative weight rather than adiposity, it is recommended widely for use among children and adolescents to determine overweight and is the currently preferred measure. The risk of adult overweight from childhood overweight provides the best available evidence to judge the clinical validity of BMI as an overweight criterion for children and adolescents. BMI measures in childhood track to adulthood moderately or very well, with stronger tracking seen for children with >or=1 obese parent and children who are more overweight or older. The probability of adult obesity (BMI of >30 kg/m(2)) is >or=50% among children >13 years of age whose BMI percentiles meet or exceed the 95th percentile for age and gender. BMI-based overweight categorization for individuals, particularly for racial/ethnic minorities with differences in body composition, may have limited validity because BMI measures cannot differentiate between increased weight for height attributable to relatively greater fat-free mass (muscle, bone, and fluids) and that attributable to greater fat. No trials of screening programs to identify and to treat childhood overweight have been reported. Limited research is available on effective, generalizable interventions for overweight children and adolescents that can be conducted in primary care settings or through primary care referrals.

CONCLUSIONS: BMI measurements of overweight among older adolescents identify those at increased risk of developing adult obesity. Interventions to treat overweight adolescents in clinical settings have not been shown to have clinically significant benefits, and they are not widely available. Screening to categorize overweight among children under age 12 or 13 who are not clearly overweight may not provide reliable risk categorization for adult obesity. Screening in this age group is compromised by the fact that there is little generalizable evidence for primary care interventions. Because existing trials report modest short- to medium-term improvements (approximately 10-20% decrease in percentage of overweight or a few units of change in BMI), however, overweight improvements among children and adolescents seem possible.