Guide to Clinical Preventive Services, 2008

Metabolic, Nutritional, and Endocrine Conditions

Behavioral Counseling in Primary Care to Promote a Healthy Diet

Summary of Recommendations The U.S. Preventive Services Task Force (USPSTF) concludes that the evidence is insufficient to recommend for or against routine behavioral counseling to promote a healthy diet in unselected patients in primary care settings. Grade: I Statement. The USPSTF recommends intensive behavioral dietary counseling for adult patients with hyperlipidemia and other known risk factors for cardiovascular and diet-related chronic disease. Intensive counseling can be delivered by primary care clinicians or by referral to other specialists, such as nutritionists or dietitians. Grade: B Recommendation.

This USPSTF recommendation was first published in:  Am J Prev Med 2003;24(1):93-100.
To read the recommendation, go to: http://www.ahrq.gov/clinic/3rduspstf/diet/dietrr.htm.

Clinical Considerations

• Several brief dietary assessment questionnaires have been validated for use in the primary care setting.^48,49 These instruments can identify dietary counseling needs, guide interventions, and monitor changes in patients' dietary patterns. However, these instruments are susceptible to the bias of the respondent. Therefore, when used to evaluate the efficacy of counseling, efforts to verify self-reported information are recommended since patients receiving dietary interventions may be more likely to report positive changes in dietary behavior than control patients.^50-53
• Effective interventions combine nutrition education with behaviorally-oriented counseling to help patients acquire the skills, motivation, and support needed to alter their daily eating patterns and food preparation practices. Examples of behaviorally-oriented counseling interventions include teaching self monitoring, training to overcome common barriers to selecting a healthy diet, helping patients to set their own goals, providing guidance in shopping and food preparation, role playing, and arranging for intra-treatment social support. In general, these interventions can be described with reference to the 5-A behavioral counseling framework:⁵⁴
  1. Assess dietary practices and related risk factors.
  2. Advise to change dietary practices.
  3. Agree on individual diet change goals.
  4. Assist to change dietary practices or address motivational barriers.
  5. Arrange regular followup and support or refer to more intensive behavioral nutritional counseling (e.g., medical nutrition therapy) if needed.
• Two approaches appear promising for the general population of adult patients in primary care settings:
  1. Medium-intensity face-to-face dietary counseling (2 to 3 group or individual sessions) delivered by a dietitian or nutritionist or by a specially trained primary care physician or nurse practitioner.
  2. Lower-intensity interventions that involve 5 minutes or less of primary care provider counseling supplemented by patient self-help materials, telephone counseling, or other interactive health communications.
  However, more research is needed to assess the long-term efficacy of these treatments and the balance of benefits and harms.
• The largest effect of dietary counseling in asymptomatic adults has been observed with more intensive interventions (multiple sessions lasting 30 minutes or longer) among patients with hyperlipidemia or hypertension, and among others at increased risk for diet-related chronic disease. Effective interventions include individual or group counseling delivered by nutritionists, dietitians, or specially trained primary care practitioners or health educators in the primary care setting or in other clinical settings by referral. Most studies of these interventions have enrolled selected patients, many of whom had known diet-related risk factors such as hyperlipidemia or hypertension. Some approaches may be effective with unselected adult patients, but adherence to dietary advice may be lower, and health benefits smaller, than in patients who have been told they are at higher risk for diet-related chronic disease.⁵⁵
• Office-level systems supports (prompts, reminders, and counseling algorithms) have been found to significantly improve the delivery of appropriate dietary counseling by primary care clinicians.^56-58
• Possible harms of dietary counseling have not been well defined or measured. Some have raised concerns that if patients focus only on reducing total fat intake without attention to reducing caloric intake, an increase in carbohydrate intake (e.g., reduced-fat or low-fat food products) may lead to weight gain, elevated triglyceride levels, or insulin resistance. Nationally, obesity rates have increased despite declining fat consumption, but studies did not consistently examine effects of counseling on outcomes such as caloric intake and weight.
• Little is known about effective dietary counseling for children or adolescents in the primary care setting. Most studies of nutritional interventions for children and adolescents have focused on nonclinical settings (such as schools) or have used physiologic outcomes such as cholesterol or weight rather than more comprehensive measures of a healthy diet.^59,60

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Screening for Hemochromatosis

Summary of Recommendation The U.S. Preventive Services Task Force (USPSTF) recommends against routine genetic screening for hereditary hemochromatosis in the asymptomatic general population. Grade: D Recommendation.

This USPSTF recommendation was first published in Ann Intern Med. 2006;145:204-208.
To read the recommendation, go to: http://www.ahrq.gov/clinic/uspstf06/hemochromatosis/hemochrs.htm

Clinical Considerations

• This recommendation applies to asymptomatic persons. This recommendation does not include individuals with signs or symptoms that would include hereditary hemochromatosis in the differential diagnosis. Furthermore, it does not include individuals with a family history of clinically detected or screening-detected probands for hereditary hemochromatosis.
• Clinically important disease due to hereditary hemochromatosis appears to be rare. Even among individuals with mutations on the hemochromatosis (HFE) gene, it appears that only a small subset will develop symptoms of hemochromatosis. An even smaller proportion of these individuals will develop advanced stages of clinical disease.
• Clinically recognized hereditary hemochromatosis is primarily associated with the HFE mutation C282Y. Although this is a relatively common mutation in the U.S. population, great racial and ethnic variations exist. The frequency of homozygosity is 4.4 per 1000 among white persons, with much lower frequencies among Hispanic persons (0.27 per 1000), black persons (0.14 per 1000), and Asian-American persons (< 0.001 per 1000). Screening of family members of probands identifies the highest prevalence of undetected C282Y homozygotes (23 percent of all family members tested), particularly among siblings (33 percent homozygosity).
• The natural history of disease due to hereditary hemochromatosis is not well understood but appears to vary considerably among individuals. Clinically recognized hereditary hemochromatosis is about twice as common in men as in women. Iron accumulation and disease expression are modified by environmental factors, including blood loss or donation, alcohol use, diet, and infections such as viral hepatitis.
• Among C282Y homozygotes newly identified in the general population by genotypic screening, 6 percent of those undergoing further evaluation had cirrhosis (representing 1.4 percent of all newly screening-identified C282Y homozygotes). Cirrhosis is a serious, late-stage disease development, and its prevention would be a major goal of screening and treatment.
• Individuals with a family member, especially a sibling, who is known to have hereditary hemochromatosis may be more likely to develop symptoms. These individuals should be counseled regarding genotyping, with further diagnostic testing as warranted as part of case-finding.
• In addition to genotyping, more common laboratory testing can sometimes identify iron overload. Clinical screening with these laboratory tests, or phenotypic screening, was not included in the evidence synthesis on which this recommendation is based. Genotyping primarily focuses on the identification of the C282Y mutation on HFE. While other mutations exist, C282Y homozygosity is most commonly associated with clinical manifestations. Identifying an individual with the genotypic predisposition does not accurately predict the future risk for disease manifestation.
• Therapeutic phlebotomy is the primary treatment for hemochromatosis. Treated individuals report inconsistent improvement of their signs and symptoms. It is uncertain whether cirrhosis at diagnosis confers a worse prognosis based on the potential lack of reversibility of liver damage. Recent research reports survival rates in treated individuals with or without cirrhosis that are similar to rates in healthy controls. The degree to which clinically important manifestations can be averted remains uncertain, as does the optimal time for early treatment.

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Hormone Therapy for the Prevention of Chronic Conditions in Postmenopausal Women

Summary of Recommendations The U.S. Preventive Services Task Force (USPSTF) recommends against the routine use of combined estrogen and progestin for the prevention of chronic conditions in postmenopausal women. Grade: D recommendation. The U.S. Preventive Services Task Force (USPSTF) recommends against the routine use of unopposed estrogen for the prevention of chronic conditions in postmenopausal women who have had a hysterectomy. Grade: D recommendation.

This USPSTF recommendation was first published in:  Ann Intern Med 2005;142:855-60.
To read the recommendation, go to: http://www.ahrq.gov/clinic/uspstf05/ht/htpostmenrs.htm.

Clinical Considerations

• The balance of benefits and harms for a woman will be influenced by her personal preferences, her risks for specific chronic diseases, and the presence of menopausal symptoms. A shared decisionmaking approach to preventing chronic diseases in perimenopausal and postmenopausal women involves consideration of individual risk factors and preferences in selecting effective interventions for reducing the risks for fracture, heart disease, and cancer. See other USPSTF recommendations for prevention of chronic diseases (screening for osteoporosis, high blood pressure, lipid disorders, breast cancer, and colorectal cancer; and counseling to prevent tobacco use) available at:  http://www.preventiveservices.ahrq.gov.
• The USPSTF did not consider the use of hormone therapy for the management of menopausal symptoms, which is the subject of recommendations by other expert groups. Women and their clinicians should discuss the balance of risks and benefits before deciding to initiate or continue hormone therapy for menopausal symptoms. For example, for combined estrogen and progestin, some risks (such as the risks for venous thromboembolism, coronary heart disease [CHD], and stroke) arise within the first 1 to 2 years of therapy, and other risks (such as the risk for breast cancer) appear to increase with longer-term hormone therapy. The populations of women using hormone therapy for symptom relief may differ from those who would use hormone therapy for prevention of chronic disease (e.g., age differences). Other expert groups have recommended that women who decide to take hormone therapy to relieve menopausal symptoms use the lowest effective dose for the shortest possible time.
• Although estrogen alone or in combination with progestin reduces the risk for fractures in women, other effective medications (e.g., bisphosphonates and calcitonin) are available for treating women with low bone density to prevent fractures. The role of chemopreventive agents in preventing fractures in women without low bone density is unclear. The USPSTF addressed screening for osteoporosis in postmenopausal women in 2002.⁶¹
• Unopposed estrogen increases the risk for endometrial cancer in women who have an intact uterus. Clinicians should use a shared decisionmaking approach when discussing the possibility of using unopposed estrogen in women who have not had a hysterectomy.⁶²

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Screening for Iron Deficiency Anemia-Including Iron Supplementation for Children and Pregnant Women

Summary of Recommendations The U.S. Preventive Services Task Force (USPSTF) concludes that evidence is insufficient to recommend for or against routine screening for iron deficiency anemia in asymptomatic children aged 6 to 12 months. Grade: I Statement. The USPSTF recommends routine screening for iron deficiency anemia in asymptomatic pregnant women. Grade: B Recommendation. The USPSTF recommends routine iron supplementation for asymptomatic children aged 6 to 12 months who are at increased risk for iron deficiency anemia (see Clinical Considerations for a discussion of increased risk). Grade: B Recommendation. The USPSTF concludes that evidence is insufficient to recommend for or against routine iron supplementation for asymptomatic children aged 6 to 12 months who are at average risk for iron deficiency anemia. Grade: I Statement. The USPSTF concludes that evidence is insufficient to recommend for or against routine iron supplementation for non-anemic pregnant women. Grade: I Statement.

This USPSTF recommendation was first published by: Agency for Healthcare Research and Quality, Rockville, MD. May 2006.
To read the recommendation, go to: http://www.ahrq.gov/clinic/uspstf06/ironsc/ironrs.htm.

Clinical Considerations

• These USPSTF recommendations address screening for iron deficiency anemia and iron supplementation in children aged 6 to 12 months who are at increased risk and average risk, in asymptomatic pregnant women, and in non-anemic pregnant women. Infants younger than 6 months of age, older children, non-pregnant women, and men are not addressed.
• Iron deficiency anemia can be defined as iron deficiency (abnormal values for serum ferritin, transferrin saturation, and free erythrocyte protoporphyrin) with a low hemoglobin or hematocrit value. Iron deficiency is much more common than iron deficiency anemia and is part of a continuum that ranges from iron depletion to iron deficiency anemia. Many of the negative health outcomes of iron deficiency are associated with its extreme manifestation, iron deficiency anemia. Iron deficiency has also been associated with negative neurodevelopmental outcomes in children.
• Other causes of anemia vary by population and include other nutritional deficiencies, abnormal hemoglobin (e.g., thalassemia), enzyme defects, and anemia associated with acute and chronic infections.
• In the U.S., race, income, education, and other socioeconomic factors are associated with iron deficiency and iron deficiency anemia. Individuals considered to be at high risk for iron deficiency include adult females, recent immigrants, and among adolescent females, fad dieters, and those who are obese. Premature and low birth weight infants are also at increased risk for iron deficiency.
• Venous hemoglobin is more accurate than capillary hemoglobin for identifying anemia. Ferritin has the highest sensitivity and specificity for diagnosing iron deficiency in anemic patients.
• Iron deficiency anemia is usually treated with oral iron preparations. The likelihood that iron deficiency anemia identified by screening will respond to treatment is unclear because many families do not adhere to treatment and because the rate of spontaneous resolution is high. 97 percent of infant formula sold in the U.S. is iron-fortified. Substantial reductions in the incidence of iron deficiency and iron deficiency anemia have been demonstrated in healthy infants fed iron-fortified formula or iron-fortified cereal, compared with infants fed cow's milk or unfortified formula.
• Iron supplements accounted for 30 percent of fatal pediatric pharmaceutical overdoses occurring between 1983 and 1990, and iron poisoning has been observed even in the context of controlled trials in which parents were instructed in the safe storage and use of iron products. A reduction in deaths of children due to iron overdose was observed when unit-dose packaging was required between 1998 and 2002; this requirement was overturned by the courts in 2003.

Screening for Obesity in Adults

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. Grade: B Recommendation. The USPSTF concludes that the evidence is insufficient to recommend for or against the use of moderate- or low-intensity counseling together with behavioral interventions to promote sustained weight loss in obese adults. Grade: I Statement. 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. Grade: I Statement.

This USPSTF recommendation was first published in:  Ann Intern Med 2003;139:930-2.
To read the recommendation, go to: http://www.ahrq.gov/clinic/3rduspstf/obesity/obesrr.htm.

Clinical Considerations

• A number of techniques, such as bioelectrical impedance, dual-energy x-ray absorptiometry, and total body water can measure body fat, but it is impractical to use them routinely. Body mass index (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 for 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 3 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 (NIH) provides a BMI calculator at www.nhlbisupport.com/bmi/ and a table at 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 1 person-to-person (individual or group) session per month for at least the first 3 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 on 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 Food and Drug Administration, can produce modest weight loss (2.6-4.8 kg) that can be sustained for at least 2 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 2 years) benefits or adverse effects of these drugs. Experts recommend that pharmacological 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 to > 40 kg) in patients with class III obesity. Clinical guidelines developed by the National Heart, Lung, and Blood Institute (NHLBI) 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 1 other obesity-related illness. The postoperative mortality rate for these procedures is 0.2 percent. Other complications include wound infection, re-operation, vitamin deficiency, diarrhea, and hemorrhage. Re-operation may be necessary in up to 25 percent of patients. Patients should receive a psychological evaluation prior to 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.

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Behavioral Counseling in Primary Care to Promote Physical Activity

Summary of Recommendation The U.S. Preventive Services Task Force (USPSTF) concludes that the evidence is insufficient to recommend for or against behavioral counseling in primary care settings to promote physical activity. Grade: I Statement.

This USPSTF recommendation was first published in:  Ann Intern Med 2002;137:205-7.
To read the recommendation, go to: http://www.ahrq.gov/clinic/3rduspstf/physactivity/physactrr.htm.

Clinical Considerations

• Regular physical activity helps prevent cardiovascular disease, hypertension, type 2 diabetes, obesity, and osteoporosis. It may also decrease all-cause morbidity and lengthen life-span.⁶³
• Benefits of physical activity are seen at even modest levels of activity, such as walking or bicycling 30 minutes per day on most days of the week. Benefits increase with increasing levels of activity.⁶⁴
• Whether routine counseling and followup by primary care physicians results in increased physical activity among their adult patients is unclear. Existing studies limit the conclusions that can be drawn about efficacy, effectiveness, and feasibility of primary care physical activity counseling. Most studies have tested brief, minimal, and low-intensity primary care interventions, such as 3 to 5 minute counseling sessions in the context of a routine clinical visit.
• Multi-component interventions combining provider advice with behavioral interventions to facilitate and reinforce healthy levels of physical activity appear the most promising. Such interventions often include patient goal setting, written exercise prescriptions, individually tailored physical activity regimens, and mailed or telephone followup assistance provided by specially trained staff. Linking primary care patients to community-based physical activity and fitness programs may enhance the effectiveness of primary care clinician counseling.⁶⁵
• Potential harms of physical activity counseling have not been well defined or studied. They may include muscle and fall-related injuries or cardiovascular events.⁶⁶ It is unclear whether more extensive patient screening, certain types of physical activity (e.g., moderate vs. vigorous exercise), more gradual increases in exercise, or more intensive counseling and followup monitoring will decrease the likelihood of injuries related to physical activity. Existing studies provide insufficient evidence regarding the potential harms of various activity protocols, such as moderate compared with vigorous exercise.

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Screening for Thyroid Disease

Summary of Recommendation The U.S. Preventive Services Task Force (USPSTF) concludes the evidence is insufficient to recommend for or against routine screening for thyroid disease in adults. Grade: I Statement.

This USPSTF recommendation was first published in:  Ann Intern Med 2004;125-7.
To read the recommendation, go to: http://www.ahrq.gov/clinic/3rduspstf/thyroid/thyrrs.htm.

Clinical Considerations

• Subclinical thyroid dysfunction is defined as an abnormal biochemical measurement of thyroid hormones without any specific clinical signs or symptoms of thyroid disease and no history of thyroid dysfunction or therapy. This includes individuals who have mildly elevated TSH and normal thyroxine (T4) and triiodothyronine (T3) levels (subclinical hypothyroidism), or low TSH and normal T4 and T3 levels (subclinical hyperthyroidism). Individuals with symptoms of thyroid dysfunction, or those with a history of thyroid disease or treatment, are excluded from this definition and are not the subject of these recommendations.
• When used to confirm suspected thyroid disease in patients referred to a specialty endocrine clinic, TSH has a high sensitivity (98 percent) and specificity (92 percent). When used for screening primary care populations, the positive predictive value (PPV) of TSH in detecting thyroid disease is low; further, the interpretation of a positive test result is often complicated by an underlying illness or by frailty of the individual. In general, values for serum TSH below 0.1 mU/L are considered low and values above 6.5 mU/L are considered elevated.
• Clinicians should be aware of subtle signs of thyroid dysfunction, particularly among those at high risk. People at higher risk for thyroid dysfunction include the elderly, post-partum women, those with high levels of radiation exposure (> 20 mGy), and patients with Down syndrome. Evaluating for symptoms of hypothyroidism is difficult in patients with Down syndrome because some symptoms and signs (e.g., slow speech, thick tongue, and slow mentation) are typical findings in both conditions.
• Subclinical hyperthyroidism has been associated with atrial fibrillation, dementia, and, less clearly, with osteoporosis. However, progression from subclinical to clinical disease in patients without a history of thyroid disease is not clearly established.
• Subclinical hypothyroidism is associated with poor obstetric outcomes and poor cognitive development in children. Evidence for dyslipidemia, atherosclerosis, and decreased quality of life in adults with subclinical hypothyroidism in the general population is inconsistent and less convincing.

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Screening for Type 2 Diabetes Mellitus in Adults

NOTE: The USPSTF revised its recommendation on this topic during publication of The Guide to Clinical Preventive Services 2008. For the most recent recommendation, please visit our Web site at http://www.preventiveservices.ahrq.gov or the USPSTF’s Electronic Preventive Services Selector (ePSS) at http://epss.ahrq.gov. You can search the ePSS for recommendations by patient age, sex, and pregnancy status, and you can download the recommendations as well as receive automatic updates to your PDA.

This USPSTF recommendation was first published in:  Ann Intern Med 2008;148:846-854.
To read the recommendation, go to: http://www.ahrq.gov/clinic/uspstf/uspsdiab.htm

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