Screening and Interventions for Overweight in Children and Adolescents: Recommendation Statement
http://www.100md.com
《小儿科》
US Preventive Services Task Force, Rockville, Maryland
ABSTRACT
The U.S. Preventive Services Task Force (USPSTF) is an independent panel of non-federal experts in prevention and primary care that systematically reviews the evidence of effectiveness and develops recommendations for clinical preventive services. This recommendation addresses the evidence for the accuracy of screening children and adolescents using BMI, the effectiveness of behavioral and pharmacologic interventions in improving health outcomes in these children, and the potential harms of routine screening and intervention. Using USPSTF methodology, an analytic framework with key questions was developed to guide the systematic review, which serves as the basis for this recommendation.
The number of children and adolescents who are overweight has more than doubled in the last 25 years. Childhood and adolescent overweight is associated with increased health risks. 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. Currently, available studies are limited by factors such as small sample sizes, poor generalizability, and variable follow-up. Based upon this critical gap in the evidence for effectiveness, 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). There are several gaps in the research evidence on screening and interventions for overweight children and adolescents in the primary care setting. Research is needed to provide well-defined and effective approaches to medical and psychological screening in children, as well as effective clinical approaches for the prevention and treatment of overweight in children that can be implemented by primary care clinicians.
Key Words: children overweight obesity screening USPSTF
Abbreviations: USPSTF, US Preventive Services Task Force RCT, randomized, controlled trial
This statement summarizes the US Preventive Services Task Force (USPSTF) recommendations on screening and interventions for overweight in children and adolescents and the supporting scientific evidence and updates the 1996 recommendations contained in the Guide to Clinical Preventive Services, Second Edition.1 Explanations of the ratings and of the strength of overall evidence are given in Appendices A and B, 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 (www.preventiveservices.ahrq.gov). The recommendation is also posted on the Web site of the National Guideline Clearinghouse (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% of children and adolescents aged 6 to 19 years are overweight and are at risk for diabetes, elevated blood lipids, and 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 BMI is a reasonable measure for identifying children and adolescents who are overweight or are at risk for becoming overweight. There is fair evidence that overweight adolescents and children aged 8 years 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 clinicians can make referrals. There is insufficient evidence to ascertain the magnitude of the potential harms of screening or prevention and treatment interventions. The USPSTF, therefore, was unable to determine the balance between potential benefits and harms for the routine screening of children and adolescents for overweight.
CLINICAL CONSIDERATIONS
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 (BMI 95th percentile for age and gender) for children aged 6 to 19 years now at 15%. 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 Guide to Community Preventive Services has identified effective population-based interventions that have been shown to increase physical activity, which may help to reduce childhood overweight.4
BMI (calculated as weight in kilograms divided by height in meters squared) percentile for age and gender 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 Centers for Disease Control and Prevention population-based references for comparison of growth distribution with those of a larger population. Being at risk for overweight is defined as a BMI between the 85th and 94th percentile for age and gender, and overweight is defined as a BMI at or above the 95th percentile for age and gender.6,7 Disadvantages of using BMI include the inability to distinguish increased fat mass from increased 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-to-hip circumference, have potential for clinical practice, treatment, research, and longitudinal tracking, although there are limitations in measurement validity, reliability, and comparability between measures.
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 lipids, 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 that are new to this age group, such as type 2 diabetes, represent "adult" morbidities that are now seen more frequently among overweight adolescents. For most overweight children, however, medical complications do not become clinically apparent for decades.
DISCUSSION
Overweight refers to increased body weight in relation to height when compared with an acceptable weight standard8 and 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 In 1999–2000, the prevalence of overweight (BMI 95th percentile for age and gender) for children aged 2 to 19 years ranged from 9.9% to 15.5%. 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%) than non-Hispanic white children (11.8%) beginning at age 6.10 Representative national data are unavailable to estimate reliably 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 is also associated with a higher prevalence of intermediate metabolic consequences, such as insulin resistance, elevated blood lipids, increased blood pressure, and impaired glucose tolerance. These conditions, which are often asymptomatic, increase the long-term risk for developing diabetes and heart disease in adulthood and are associated with persistent obesity into adulthood. However, the recent emergence of medical conditions that are "new" to overweight children, such as type 2 diabetes, 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 both 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 (aged 6–18 years) into young adulthood (aged 20–37 years) as evidenced by longitudinal studies showing low to moderate (r = 0.3–0.4) or moderate to high (r = 0.5–0.9) correlations between childhood BMI and adult BMI measures. Increased tracking (r 0.5) is seen in older children (after age 12–13 years and particularly after sexual maturity), in younger children (aged 6–12 years) and older children who are more overweight (usually above the 95th or 98th percentile), and in younger children with 1 or more obese parents. Gender differences in tracking are not consistent across ages or within age categories, and limited data are available to compare white and black children.15–21
Several fair- to good-quality longitudinal studies have examined the risks associated with childhood overweight and various adult health outcomes, including mortality, morbidity, socioeconomic status, and cardiovascular risk factors.18,22–27 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 that controlled 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 clinicians 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 aged 8 to 12 years with variable completeness of follow-up. Twelve to 24 months after intensive treatment, these studies have shown 7% to 26% decreases in the mean percentage of overweight, which may be maintained or improved after 5 to 10 years in a subset of patients.29,30 One fair-quality, randomized, controlled trial (RCT) compared a reduced-glycemic-load diet with a conventional reduced-fat diet in adolescents in an intensive 6-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/m2) and increased in the reduced-fat diet group (0.6 ± 0.5 kg/m2; P < .02).31 A fair- to poor-quality RCT examined 3 physical activity interventions that consisted 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 seen between the groups in their percentage of body fat or visceral adipose tissue.32 In a good-quality RCT with predominantly white adolescents, investigators compared an intervention group that received a single, computer-based, individually tailored counseling session followed by 9 to 12 follow-up telephone calls with a control group that received a single, nontailored counseling session in a primary care setting. At 7 months' follow-up, those in the intervention group reported no more physical activity (kcal/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).33
A fair-quality RCT compared weight loss differences of children aged 8 to 12 years in an intervention group that received 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/m2) than in boys in the control group or girls in either the intervention or the 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/m2).29
A good-quality RCT compared BMI loss differences of adolescents in an intervention group that was treated with sibutramine with a control group that was 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; 95% confidence interval: 2.0–7.4) among the adolescents in the intervention group than among those in the control group. Open-label medication that continued for 6 months resulted in weight maintenance in the intervention group and in weight loss in the control group, such that both groups had similar reductions (6.4–8.6%) 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.34 No acceptable quality evidence is available for children or adolescents to be able to evaluate the effectiveness of surgical approaches to 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 theoretical harms are inferred from studies of limited design. There also is insufficient evidence on the harms of interventions. Among 4 recent behavioral intervention trials, adverse effects were reported in 1 trial.33 Among those who completed an intervention (37 of 44) in a good-quality RCT 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 (44%) of 43 patients in the group that received sibutramine had their dosage reduced or discontinued because of elevated blood pressure, pulse rate, or both. No other adverse events were reported.34
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 past 2 decades on the basis of the doubling of children who have been hospitalized for overweight-related asthma, diabetes, sleep apnea, and gall bladder disease and on lengthened hospital stays for overweight children.35
Future Research
There are several gaps in the research evidence on screening and interventions for overweight children and adolescents in the primary care setting. Research that is needed to improve the definition of overweight in children includes refinement of BMI measurement for use in children, longitudinal studies from childhood to adulthood that control for risk factors and sociodemographics, and continued investigation of growth trajectories and susceptible periods for the development of overweight and their role as predictors of adult overweight and obesity. Research is needed to provide well-defined and effective approaches to medical and psychological screening in children. Research is also needed on effective clinical approaches for the prevention and treatment of overweight in children that can be implemented by primary care clinicians, as well as on whether screening and intensive management of cardiovascular disease, diabetes, or other disease risk factors in overweight adolescents is beneficial. Research is needed to examine changes in morbidity among children and adolescents who lose weight and maintain their weight loss and those who regain weight in adulthood. Last, research is needed to help us understand whether preventing current or future excess costs associated with overweight is cost-effective, given different scenarios for treatment reimbursement and intervention effectiveness.36
Recommendations of Other Groups
The American Academy of Pediatrics and the Expert Committee from the Maternal and Child Health Bureau, Health Resources and Services Administration,37,38 recommend using BMI to follow the weight status of children and adolescents. Both groups recommend identifying familial risk factors and possible health complications associated with childhood overweight (eg, hypertension, dyslipidemias, insulin resistance). In 2004, the Institute of Medicine developed a prevention-focused action plan, "Preventing Childhood Obesity: Health in the Balance," which calls for "immediate action" and provides recommendations that are "based on the best available evidence—as opposed to waiting for the best possible evidence." The Institute of Medicine action plan also recommends that health professionals routinely track BMI in children and adolescents, in addition to other community-based recommendations.39
APPENDIX A: USPSTF RECOMMENDATIONS AND RATINGS
The USPSTF grades its recommendations according to 1 of 5 classifications (A, B, C, D, I), reflecting the strength of evidence and magnitude of net benefit (benefits minus harms):
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.
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.
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.
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.
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.
APPENDIX B: USPSTF STRENGTH OF OVERALL EVIDENCE
The USPSTF grades the quality of the overall evidence for a service on a 3-point scale (good, fair, 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.
ACKNOWLEDGMENTS
This is AHRQ Publication No. AHRQ 05-0574-A and is being published here first.
MEMBERS OF THE USPSTF
Members of the US Preventive Services Task Force are Ned Calonge, MD, MPH, Chair, USPSTF (Acting Chief Medical Officer and State Epidemiologist, Colorado Department of Public Health and Environment, Denver, CO); Janet D. Allan, PhD, RN, CS, Vice-Chair, USPSTF (Dean, School of Nursing, University of Maryland, Baltimore, Baltimore, MD); Alfred O. Berg, MD, MPH (Professor and Chair, Department of Family Medicine, University of Washington, Seattle, WA); Paul S. Frame, MD (Family Physician, Tri-County Family Medicine, Cohocton, NY, and Clinical Professor of Family Medicine, University of Rochester, Rochester, NY); Joxel Garcia, MD, MBA (Deputy Director, Pan American Health Organization, Washington, DC); Russell Harris, MD, MPH (Professor of Medicine, Sheps Center for Health Services Research, University of North Carolina School of Medicine, Chapel Hill, NC); Mark S. Johnson, MD, MPH (Professor and Chair, Department of Family Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ); Jonathan D. Klein, MD, MPH (Associate Professor, Department of Pediatrics, University of Rochester School of Medicine, Rochester, NY); Carol Loveland-Cherry, PhD, RN (Executive Associate Dean, School of Nursing, University of Michigan, Ann Arbor, MI); Virginia A. Moyer, MD, MPH (Professor, Department of Pediatrics, University of Texas Health Science Center, Houston, TX); C. Tracy Orleans, PhD (Senior Scientist, The Robert Wood Johnson Foundation, Princeton, NJ); Albert L. Siu, MD, MSPH (Professor and Chairman, Brookdale Department of Geriatrics and Adult Development, Mount Sinai Medical Center, New York, NY); Steven M. Teutsch, MD, MPH (Executive Director, Outcomes Research and Management, Merck & Company, Inc, West Point, PA); Carolyn Westhoff, MD (Professor of Obstetrics and Gynecology and Professor of Public Health, Columbia University, New York, NY); and Steven H. Woolf, MD, MPH (Professor, Department of Family Practice and Department of Preventive and Community Medicine and Director of Research, Department of Family Practice, Virginia Commonwealth University, Fairfax, VA). For a list of current Task Force members, go to www.ahrq.gov/clinic/uspstfab.htm.
FOOTNOTES
Accepted Apr 19, 2005.
Recommendations made by the US Preventive Services Task Force are independent of the US government. They should not be construed as an official position of the Agency for Healthcare Research and Quality or the US Department of Health and Human Services.
No conflict of interest declared.
REFERENCES
US Preventive Services Task Force. Guide to Clinical Preventive Services. 2nd ed. Washington, DC: Office of Disease Prevention and Health Promotion; 1996
Dietz WH, Robinson TN. Use of the body mass index (BMI) as a measure of overweight in children and adolescents. J Pediatr.1998; 132 :191 –193
Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000 CDC Growth Charts for the United States: methods and development. Vital Health Stat 11.2002; (246):1 –190
Fomom SJ, Haschke F, Ziegler EE, Nelson SE. Body composition of reference children from birth to age 10 years. Am J Clin Nutr.1982; 35(suppl) :1169 –1175
Ogden CL, Carroll MD, Flegal KM. Epidemiologic trends in overweight and obesity. Endocrinol Metab Clin North Am.2003; 32 :741 –760, vii
Lobstein T, Baur L, Uauy R. Obesity in children and young people: a crisis in public health. Obes Rev.2004; 5 (suppl 1):4–104
Must A, Strauss RS. Risks and consequences of childhood and adolescent obesity. Int J Obes Relat Metab Disord.1999; 23 (suppl 2):S2–S11
Zametkin AJ, Zoon CK, Klein HW, Munson S. Psychiatric aspects of child and adolescent obesity: a review of the past 10 years. J Am Acad Child Adolesc Psychiatry.2004; 43 :134 –150
Cook S, Weitzman M, Auinger P, Nguyen M, Dietz WH. Prevalence of a metabolic syndrome phenotype in adolescents: findings from the third National Health and Nutrition Examination Survey, 1988–1994. Arch Pediatr Adolesc Med.2003; 157 :821 –827
Freedman DS, Dietz WH, Tang R, et al. The relation of obesity throughout life to carotid intima-media thickness in adulthood: the Bogalusa Heart Study. Int J Obes Relat Metab Disord.2004; 28 :159 –166
Casey VA, Dwyer JT, Coleman KA, Valadian I. Body mass index from childhood to middle age: a 50-y follow-up. Am J Clin Nutr.1992; 56 :14 –18
Lauer RM, Lee J, Clarke WR. Factors affecting the relationship between childhood and adult cholesterol levels: the Muscatine Study. Pediatrics.1988; 82 :309 –318
Lauer RM, Lee J, Clarke WR. Predicting adult cholesterol levels from measurements in childhood and adolescence: the Muscatine Study. Bull N Y Acad Med.1989; 65 :1127 –1142
Clarke WR, Lauer RM. Does childhood obesity track into adulthood Crit Rev Food Sci Nutr.1993; 33 :423 –430
Whitaker RC, Wright JA, Pepe MS, Seidel KD, Dietz WH. Predicting obesity in young adulthood from childhood and parental obesity. N Engl J Med.1997; 337 :869 –873
Wattigney WA, Webber LS, Srinivasan SR, Berenson GS. The emergence of clinically abnormal levels of cardiovascular disease risk factor variables among young adults: the Bogalusa Heart Study. Prev Med.1995; 24 :617 –626
Lauer RM, Clarke WR, Burns TL. Obesity in childhood: the Muscatine Study. Zhonghua Min Guo Xiao Er Ke Yi Xue Hui Za Zhi.1997; 38 :432 –437
Srinivasan SR, Myers L, Berenson GS. Predictability of childhood adiposity and insulin for developing insulin resistance syndrome (syndrome X) in young adulthood: the Bogalusa Heart Study. Diabetes.2002; 51 :204 –209
Sinaiko AR, Donahue RP, Jacobs DR Jr, Prineas RJ. Relation of weight and rate of increase in weight during childhood and adolescence to body size, blood pressure, fasting insulin, and lipids in young adults. The Minneapolis Children's Blood Pressure Study. Circulation.1999; 99 :1471 –1476
Bao W, Srinivasan SR, Wattigney WA, Bao W, Berenson GS. Usefulness of childhood low-density lipoprotein cholesterol level in predicting adult dyslipidemia and other cardiovascular risks. The Bogalusa Heart Study. Arch Intern Med.1996; 156 :1315 –1320
Freedman DS, Khan LK, Serdula MK, Dietz WH, Srinivasan SR, Berenson GS. Inter-relationships among childhood BMI, childhood height, and adult obesity: the Bogalusa Heart Study. Int J Obes Relat Metab Disord.2004; 28 :10 –16
Lauer RM, Clarke WR. Childhood risk factors for high adult blood pressure: the Muscatine Study. Pediatrics.1989; 84 :633 –641
Freedman DS, Khan LK, Dietz WH, Srinivasan SR, Berenson GS. Relationship of childhood obesity to coronary heart disease risk factors in adulthood: the Bogalusa Heart Study. Pediatrics.2001; 108 :712 –718
Epstein LH, Roemmich JN, Raynor HA. Behavioral therapy in the treatment of pediatric obesity. Pediatr Clin North Am.2001; 48 :981 –993
Epstein LH, Valoski A, Wing RR, McCurley J. Ten-year outcomes of behavioral family-based treatment for childhood obesity. Health Psychol.1994; 13 :373 –383
Ebbeling CB, Leidig MM, Sinclair KB, Hangen JP, Ludwig DS. A reduced-glycemic load diet in the treatment of adolescent obesity. Arch Pediatr Adolesc Med.2003; 157 :773 –779
Gutin B, Barbeau P, Owens S, et al. Effects of exercise intensity on cardiovascular fitness, total body composition, and visceral adiposity of obese adolescents. Am J Clin Nutr.2002; 75 :818 –826
Saelens BE, Sallis JF, Wilfley DE, Patrick K, Cella JA, Buchta R. Behavioral weight control for overweight adolescents initiated in primary care. Obes Res.2002; 10 :22 –32
Berkowitz RI, Wadden TA, Tershakovec AM, Cronquist JL. Behavior therapy and sibutramine for the treatment of adolescent obesity: a randomized controlled trial. JAMA.2003; 289 :1805 –1812
Tershakovec AM, Watson MH, Wenner WJ Jr, Marx AL. Insurance reimbursement for the treatment of obesity in children. J Pediatr.1999; 134 :573 –578
Institute of Medicine. Preventing childhood obesity: health in the balance. Washington, DC: Institute of Medicine; 2004. Available at: www.iom.edu/report.aspid=22596. Accessed November 29, 2004(US Preventive Services Ta)
ABSTRACT
The U.S. Preventive Services Task Force (USPSTF) is an independent panel of non-federal experts in prevention and primary care that systematically reviews the evidence of effectiveness and develops recommendations for clinical preventive services. This recommendation addresses the evidence for the accuracy of screening children and adolescents using BMI, the effectiveness of behavioral and pharmacologic interventions in improving health outcomes in these children, and the potential harms of routine screening and intervention. Using USPSTF methodology, an analytic framework with key questions was developed to guide the systematic review, which serves as the basis for this recommendation.
The number of children and adolescents who are overweight has more than doubled in the last 25 years. Childhood and adolescent overweight is associated with increased health risks. 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. Currently, available studies are limited by factors such as small sample sizes, poor generalizability, and variable follow-up. Based upon this critical gap in the evidence for effectiveness, 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). There are several gaps in the research evidence on screening and interventions for overweight children and adolescents in the primary care setting. Research is needed to provide well-defined and effective approaches to medical and psychological screening in children, as well as effective clinical approaches for the prevention and treatment of overweight in children that can be implemented by primary care clinicians.
Key Words: children overweight obesity screening USPSTF
Abbreviations: USPSTF, US Preventive Services Task Force RCT, randomized, controlled trial
This statement summarizes the US Preventive Services Task Force (USPSTF) recommendations on screening and interventions for overweight in children and adolescents and the supporting scientific evidence and updates the 1996 recommendations contained in the Guide to Clinical Preventive Services, Second Edition.1 Explanations of the ratings and of the strength of overall evidence are given in Appendices A and B, 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 (www.preventiveservices.ahrq.gov). The recommendation is also posted on the Web site of the National Guideline Clearinghouse (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% of children and adolescents aged 6 to 19 years are overweight and are at risk for diabetes, elevated blood lipids, and 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 BMI is a reasonable measure for identifying children and adolescents who are overweight or are at risk for becoming overweight. There is fair evidence that overweight adolescents and children aged 8 years 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 clinicians can make referrals. There is insufficient evidence to ascertain the magnitude of the potential harms of screening or prevention and treatment interventions. The USPSTF, therefore, was unable to determine the balance between potential benefits and harms for the routine screening of children and adolescents for overweight.
CLINICAL CONSIDERATIONS
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 (BMI 95th percentile for age and gender) for children aged 6 to 19 years now at 15%. 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 Guide to Community Preventive Services has identified effective population-based interventions that have been shown to increase physical activity, which may help to reduce childhood overweight.4
BMI (calculated as weight in kilograms divided by height in meters squared) percentile for age and gender 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 Centers for Disease Control and Prevention population-based references for comparison of growth distribution with those of a larger population. Being at risk for overweight is defined as a BMI between the 85th and 94th percentile for age and gender, and overweight is defined as a BMI at or above the 95th percentile for age and gender.6,7 Disadvantages of using BMI include the inability to distinguish increased fat mass from increased 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-to-hip circumference, have potential for clinical practice, treatment, research, and longitudinal tracking, although there are limitations in measurement validity, reliability, and comparability between measures.
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 lipids, 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 that are new to this age group, such as type 2 diabetes, represent "adult" morbidities that are now seen more frequently among overweight adolescents. For most overweight children, however, medical complications do not become clinically apparent for decades.
DISCUSSION
Overweight refers to increased body weight in relation to height when compared with an acceptable weight standard8 and 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 In 1999–2000, the prevalence of overweight (BMI 95th percentile for age and gender) for children aged 2 to 19 years ranged from 9.9% to 15.5%. 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%) than non-Hispanic white children (11.8%) beginning at age 6.10 Representative national data are unavailable to estimate reliably 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 is also associated with a higher prevalence of intermediate metabolic consequences, such as insulin resistance, elevated blood lipids, increased blood pressure, and impaired glucose tolerance. These conditions, which are often asymptomatic, increase the long-term risk for developing diabetes and heart disease in adulthood and are associated with persistent obesity into adulthood. However, the recent emergence of medical conditions that are "new" to overweight children, such as type 2 diabetes, 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 both 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 (aged 6–18 years) into young adulthood (aged 20–37 years) as evidenced by longitudinal studies showing low to moderate (r = 0.3–0.4) or moderate to high (r = 0.5–0.9) correlations between childhood BMI and adult BMI measures. Increased tracking (r 0.5) is seen in older children (after age 12–13 years and particularly after sexual maturity), in younger children (aged 6–12 years) and older children who are more overweight (usually above the 95th or 98th percentile), and in younger children with 1 or more obese parents. Gender differences in tracking are not consistent across ages or within age categories, and limited data are available to compare white and black children.15–21
Several fair- to good-quality longitudinal studies have examined the risks associated with childhood overweight and various adult health outcomes, including mortality, morbidity, socioeconomic status, and cardiovascular risk factors.18,22–27 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 that controlled 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 clinicians 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 aged 8 to 12 years with variable completeness of follow-up. Twelve to 24 months after intensive treatment, these studies have shown 7% to 26% decreases in the mean percentage of overweight, which may be maintained or improved after 5 to 10 years in a subset of patients.29,30 One fair-quality, randomized, controlled trial (RCT) compared a reduced-glycemic-load diet with a conventional reduced-fat diet in adolescents in an intensive 6-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/m2) and increased in the reduced-fat diet group (0.6 ± 0.5 kg/m2; P < .02).31 A fair- to poor-quality RCT examined 3 physical activity interventions that consisted 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 seen between the groups in their percentage of body fat or visceral adipose tissue.32 In a good-quality RCT with predominantly white adolescents, investigators compared an intervention group that received a single, computer-based, individually tailored counseling session followed by 9 to 12 follow-up telephone calls with a control group that received a single, nontailored counseling session in a primary care setting. At 7 months' follow-up, those in the intervention group reported no more physical activity (kcal/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).33
A fair-quality RCT compared weight loss differences of children aged 8 to 12 years in an intervention group that received 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/m2) than in boys in the control group or girls in either the intervention or the 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/m2).29
A good-quality RCT compared BMI loss differences of adolescents in an intervention group that was treated with sibutramine with a control group that was 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; 95% confidence interval: 2.0–7.4) among the adolescents in the intervention group than among those in the control group. Open-label medication that continued for 6 months resulted in weight maintenance in the intervention group and in weight loss in the control group, such that both groups had similar reductions (6.4–8.6%) 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.34 No acceptable quality evidence is available for children or adolescents to be able to evaluate the effectiveness of surgical approaches to 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 theoretical harms are inferred from studies of limited design. There also is insufficient evidence on the harms of interventions. Among 4 recent behavioral intervention trials, adverse effects were reported in 1 trial.33 Among those who completed an intervention (37 of 44) in a good-quality RCT 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 (44%) of 43 patients in the group that received sibutramine had their dosage reduced or discontinued because of elevated blood pressure, pulse rate, or both. No other adverse events were reported.34
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 past 2 decades on the basis of the doubling of children who have been hospitalized for overweight-related asthma, diabetes, sleep apnea, and gall bladder disease and on lengthened hospital stays for overweight children.35
Future Research
There are several gaps in the research evidence on screening and interventions for overweight children and adolescents in the primary care setting. Research that is needed to improve the definition of overweight in children includes refinement of BMI measurement for use in children, longitudinal studies from childhood to adulthood that control for risk factors and sociodemographics, and continued investigation of growth trajectories and susceptible periods for the development of overweight and their role as predictors of adult overweight and obesity. Research is needed to provide well-defined and effective approaches to medical and psychological screening in children. Research is also needed on effective clinical approaches for the prevention and treatment of overweight in children that can be implemented by primary care clinicians, as well as on whether screening and intensive management of cardiovascular disease, diabetes, or other disease risk factors in overweight adolescents is beneficial. Research is needed to examine changes in morbidity among children and adolescents who lose weight and maintain their weight loss and those who regain weight in adulthood. Last, research is needed to help us understand whether preventing current or future excess costs associated with overweight is cost-effective, given different scenarios for treatment reimbursement and intervention effectiveness.36
Recommendations of Other Groups
The American Academy of Pediatrics and the Expert Committee from the Maternal and Child Health Bureau, Health Resources and Services Administration,37,38 recommend using BMI to follow the weight status of children and adolescents. Both groups recommend identifying familial risk factors and possible health complications associated with childhood overweight (eg, hypertension, dyslipidemias, insulin resistance). In 2004, the Institute of Medicine developed a prevention-focused action plan, "Preventing Childhood Obesity: Health in the Balance," which calls for "immediate action" and provides recommendations that are "based on the best available evidence—as opposed to waiting for the best possible evidence." The Institute of Medicine action plan also recommends that health professionals routinely track BMI in children and adolescents, in addition to other community-based recommendations.39
APPENDIX A: USPSTF RECOMMENDATIONS AND RATINGS
The USPSTF grades its recommendations according to 1 of 5 classifications (A, B, C, D, I), reflecting the strength of evidence and magnitude of net benefit (benefits minus harms):
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.
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.
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.
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.
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.
APPENDIX B: USPSTF STRENGTH OF OVERALL EVIDENCE
The USPSTF grades the quality of the overall evidence for a service on a 3-point scale (good, fair, 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.
ACKNOWLEDGMENTS
This is AHRQ Publication No. AHRQ 05-0574-A and is being published here first.
MEMBERS OF THE USPSTF
Members of the US Preventive Services Task Force are Ned Calonge, MD, MPH, Chair, USPSTF (Acting Chief Medical Officer and State Epidemiologist, Colorado Department of Public Health and Environment, Denver, CO); Janet D. Allan, PhD, RN, CS, Vice-Chair, USPSTF (Dean, School of Nursing, University of Maryland, Baltimore, Baltimore, MD); Alfred O. Berg, MD, MPH (Professor and Chair, Department of Family Medicine, University of Washington, Seattle, WA); Paul S. Frame, MD (Family Physician, Tri-County Family Medicine, Cohocton, NY, and Clinical Professor of Family Medicine, University of Rochester, Rochester, NY); Joxel Garcia, MD, MBA (Deputy Director, Pan American Health Organization, Washington, DC); Russell Harris, MD, MPH (Professor of Medicine, Sheps Center for Health Services Research, University of North Carolina School of Medicine, Chapel Hill, NC); Mark S. Johnson, MD, MPH (Professor and Chair, Department of Family Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ); Jonathan D. Klein, MD, MPH (Associate Professor, Department of Pediatrics, University of Rochester School of Medicine, Rochester, NY); Carol Loveland-Cherry, PhD, RN (Executive Associate Dean, School of Nursing, University of Michigan, Ann Arbor, MI); Virginia A. Moyer, MD, MPH (Professor, Department of Pediatrics, University of Texas Health Science Center, Houston, TX); C. Tracy Orleans, PhD (Senior Scientist, The Robert Wood Johnson Foundation, Princeton, NJ); Albert L. Siu, MD, MSPH (Professor and Chairman, Brookdale Department of Geriatrics and Adult Development, Mount Sinai Medical Center, New York, NY); Steven M. Teutsch, MD, MPH (Executive Director, Outcomes Research and Management, Merck & Company, Inc, West Point, PA); Carolyn Westhoff, MD (Professor of Obstetrics and Gynecology and Professor of Public Health, Columbia University, New York, NY); and Steven H. Woolf, MD, MPH (Professor, Department of Family Practice and Department of Preventive and Community Medicine and Director of Research, Department of Family Practice, Virginia Commonwealth University, Fairfax, VA). For a list of current Task Force members, go to www.ahrq.gov/clinic/uspstfab.htm.
FOOTNOTES
Accepted Apr 19, 2005.
Recommendations made by the US Preventive Services Task Force are independent of the US government. They should not be construed as an official position of the Agency for Healthcare Research and Quality or the US Department of Health and Human Services.
No conflict of interest declared.
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