Screening for Obesity in Adults: Recommendations and Rationale



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This statement summarizes the U.S. Preventive Services Task Force (USPSTF) recommendations on screening for obesity in adults based on the USPSTF's examination of evidence specific to obesity and overweight in adults. It updates the 1996 recommendations contained in the Guide to Clinical Preventive Service: Second Edition: Periodic Updates.1  Explanations of the ratings and strength of overall evidence are given in Tables 1 and 2. The complete information on which this statement is based, including evidence tables and references, is available in the summary of the evidence2 and in the systematic evidence review, “Screening and Interventions for Overweight and Obesity in Adults.”3 The USPSTF recommendations, accompanying summary article, and complete systematic evidence review are available through the USPSTF Web site (http://www.uspreventiveservicestaskforce.org). The recommendation statement and summary of the evidence also are available from the AHRQ Publications Clearinghouse in print through subscription to the Guide to Clinical Preventive Services, Third Edition: Periodic Updates. To order, contact the Clearinghouse at 800–358–9295 or e-mail ahrqpubs@ahrq.gov.

TABLE 1

USPSTF Recommendations and Ratings

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.


USPSTF = U.S. Preventive Services Task Force.

TABLE 1   USPSTF Recommendations and Ratings

View Table

TABLE 1

USPSTF Recommendations and Ratings

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.


USPSTF = U.S. Preventive Services Task Force.

Summary of Recommendations

  • The USPSTF recommends that clinicians screen all adult patients for obesity and offer intensive counseling and behavioral interventions to promote sustained weight loss for obese adults. B recommendation.

The USPSTF found good evidence that body mass index (BMI), calculated as weight in kilograms divided by height in meters squared, is reliable and valid for identifying adults at increased risk for mortality and morbidity due to overweight and obesity. There is fair to good evidence that high-intensity counseling about diet, exercise, or both, together with behavioral interventions aimed at skill development, motivation, and support strategies produces modest, sustained weight loss (typically 3 to 5 kg for one year or more) in adults who are obese (i.e., BMI of 30 kg per m2 or greater). Although the USPSTF did not find direct evidence that behavioral interventions lower mortality or morbidity from obesity, the USPSTF concluded that changes in intermediate outcomes, such as improved glucose metabolism, lipid levels, and blood pressure, from modest weight loss provide indirect evidence of health benefits. No evidence was found that addressed the harms of counseling and behavioral interventions. The USPSTF concluded that the benefits of screening and behavioral interventions outweigh potential harms.

  • The USPSTF concludes that the evidence is insufficient to recommend for or against the use of moderate- or low-intensity counseling combined with behavioral interventions to promote sustained weight loss in obese adults. I recommendation.

The USPSTF found limited evidence to determine whether moderate- or low-intensity counseling combined with behavioral interventions produces sustained weight loss in obese adults. The relevant studies were of fair to good quality but showed mixed results. In addition, studies were limited by small sample sizes, high dropout rates, potential for selection bias, and reporting the average weight change instead of the frequency of response to the intervention. As a result, the USPSTF could not determine the balance of benefits and potential harms of these types of interventions.

TABLE 2

USPSTF Strength of Overall Evidence

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.


USPSTF = U.S. Preventive Services Task Force.

TABLE 2   USPSTF Strength of Overall Evidence

View Table

TABLE 2

USPSTF Strength of Overall Evidence

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.


USPSTF = U.S. Preventive Services Task Force.

  • The USPSTF concludes that the evidence is insufficient to recommend for or against the use of counseling of any intensity and behavioral interventions to promote sustained weight loss in overweight adults. I recommendation.

The USPSTF found limited data that addressed the efficacy of counseling-based interventions in overweight adults (i.e., BMI of 25 to 29.9 kg per m2). As a result, the USPSTF could not determine the balance of benefits and potential harms of counseling to promote sustained weight loss in overweight adults.

Clinical Considerations

  • A number of techniques, such as bioelectrical impedance, dual-energy x-ray absorptiometry, and total body water immersion can measure body fat, but it is impractical to use them routinely. BMI, which is simply weight adjusted for height, is a more practical and widely used method to screen for obesity. Increased BMI is associated with an increase in adverse health effects. Central adiposity increases the risk for cardiovascular and other diseases independent of obesity. Clinicians may use the waist circumference as a measure of central adiposity. Men with waist circumferences greater than 102 cm (40 inches) and women with waist circumferences greater than 88 cm (35 inches) are at increased risk for cardiovascular disease. The waist circumference thresholds are not reliable in patients with a BMI greater than 35.

  • Expert committees have issued guidelines defining overweight and obesity based on BMI. Persons with a BMI between 25 and 29.9 are overweight and those with a BMI of 30 and above are obese. There are three classes of obesity: class I (BMI 30–34.9), class II (BMI 35–39.9), and class III (BMI 40 and above). BMI is calculated either as weight in pounds divided by height in inches squared multiplied by 703, or as weight in kilograms divided by height in meters squared. The National Institutes of Health provides a BMI calculator at http://www.nhlbisupport.com/bmi and a table at http://www.nhlbi.nih.gov/guidelines/obesity/bmi_tbl.htm.

  • The most effective interventions combine nutrition education and diet and exercise counseling with behavioral strategies to help patients acquire the skills and supports needed to change eating patterns and to become physically active. The 5-A framework (Assess, Advise, Agree, Assist, and Arrange) has been used in behavioral counseling interventions such as smoking cessation and may be a useful tool to help clinicians guide interventions for weight loss. Initial interventions paired with maintenance interventions help ensure that weight loss will be sustained over time.

  • It is advisable to refer obese patients to programs that offer intensive counseling and behavioral interventions for optimal weight loss. The USPSTF defined intensity of counseling by the frequency of the intervention. A high-intensity intervention is more than one person-to-person (individual or group) session per month for at least the first three months of the intervention. A medium-intensity intervention is a monthly intervention, and anything less frequent is a low-intensity intervention. There are limited data on the best place for these interventions to occur and on the composition of the multidisciplinary team that should deliver high-intensity interventions.

  • The USPSTF concluded that the evidence about the effectiveness of interventions with obese people may not be generalizable to adults who are overweight but not obese. The evidence for the effectiveness of interventions for weight loss among overweight adults, compared with obese adults, is limited.

  • Orlistat and sibutramine, approved for weight loss by the U.S. Food and Drug Administration, can produce modest weight loss (2.6 to 4.8 kg) that can be sustained for at least two years if the medication is continued. The adverse effects of orlistat include fecal urgency, oily spotting, and flatulence; the adverse effects of sibutramine include an increase in blood pressure and heart rate. There are no data on the long-term (longer than two years) benefits or adverse effects of these drugs. Experts recommend that pharmacologic treatment of obesity be used only as part of a program that also includes lifestyle modification interventions, such as intensive diet and/or exercise counseling and behavioral interventions.

  • There is fair to good evidence to suggest that surgical interventions such as gastric bypass, vertical banded gastroplasty, and adjustable gastric banding can produce substantial weight loss (28 kg to more than 40 kg) in patients with class III obesity. Clinical guidelines developed by the National Heart, Lung, and Blood Institute Expert Panel on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults recommend that these procedures be reserved for patients with class III obesity and for patients with class II obesity who have at least one other obesity-related illness. The postoperative mortality rate for these procedures is 0.2 percent. Other complications include wound infection, reoperation, vitamin deficiency, diarrhea, and hemorrhage. Reoperation may be necessary in up to 25 percent of patients. Patients should receive a psychologic evaluation before undergoing these procedures. The long-term health effects of surgery for obesity are not well characterized.

  • The data supporting the effectiveness of interventions to promote weight loss are derived mostly from women, especially white women. The effectiveness of the interventions is less well established in other populations, including the elderly. The USPSTF believes that, although the data are limited, these interventions may be used with obese men, physiologically mature older adolescents, and diverse populations, taking into account cultural and other individual factors.

The Scientific Evidence and Recommendations of Others sections that usually are included in USPSTF recommendation statements are available in the full recommendation and rationale statement on the USPSTF Web site (http://www.ahrq.gov/clinic/uspstfix.htm).

Address correspondence to Ned Calonge, M.D., M.P.H., Chair, U.S. Preventive Services Task Force, c/o Program Director, USPSTF, Agency for Healthcare Research and Quality, 540 Gaither Rd., Rockville, MD 20850 (e-mail: uspstf@ahrq.gov).

The U.S. Preventive Services Task Force recommendations are independent of the U.S. government. They do not represent the views of the Agency for Healthcare Research and Quality, the U.S. Department of Health and Human Services, or the U.S. Public Health Service.

 

REFERENCES

1. U.S. Preventive Services Task Force. Guide to Clinical Preventive Services. 2d ed. Washington, D.C.: Office of Disease Prevention and Health Promotion, 1996.

2. McTigue KM, Harris R, Hemphill B, Lux L, Sutton S, Bunton AJ, Lohr KN. Screening and interventions for obesity in adults: summary of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med. 2003;139:933–49.

3. McTigue K, Harris R, Hemphill MB, Bunton AJ, Lux LJ, Sutton S, et al. Screening and interventions for overweight and obesity in adults. Systematic Evidence Review No. 21 (Prepared by the Research Triangle Institute-University of North Carolina Evidence-based Practice Center under Contract No. 290–97–0011). Rockville, Md.: Agency for Healthcare Research and Quality, 2003. Accessed February 2004 at: http://www.ahrq.gov/clinic/prev/obesinv.htm.

This is one in a series excerpted from the Recommendations and Rationale Statements released by the current U.S. Preventive Services Task Force (USPSTF). These statements address preventive health services for use in primary care clinical settings, including screening tests, counseling, and chemoprevention. This statement is part of AFP's CME. See “Clinical Quiz” on page 1857.



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