Guide to Clinical Preventive Services, 2008

Heart, Vascular, and Respiratory Diseases

Screening for Abdominal Aortic Aneurysm

Summary of Recommendations The U.S. Preventive Services Task Force (USPSTF) recommends one-time screening for abdominal aortic aneurysm (AAA) by ultrasonography in men aged 65 to 75 who have ever smoked. Grade: B Recommendation. The USPSTF makes no recommendation for or against screening for AAA in men aged 65 to 75 who have never smoked. Grade: C Recommendation. The USPSTF recommends against routine screening for AAA in women. Grade: D Recommendation.

This USPSTF recommendation was first published in: Ann Intern Med. 2005;142:198-202.
To read the recommendation, go to: http://www.ahrq.gov/clinic/uspstf05/aaascr/aaars.htm.

Clinical Considerations

• The major risk factors for abdominal aortic aneurysm (AAA) include age (being 65 or older), male sex, and a history of ever smoking (at least 100 cigarettes in a person's lifetime). A first-degree family history of AAA requiring surgical repair also elevates a man's risk for AAA; this may also be true for women but the evidence is less certain. There is only a modest association between risk factors for atherosclerotic disease and AAA.
• Screening for AAA would most benefit those who have a reasonably high probability of having an AAA large enough, or that will become large enough, to benefit from surgery. In general, adults younger than age 65 and adults of any age who have never smoked are at low risk for AAA and are not likely to benefit from screening. Among men aged 65 to 74, an estimated 500 who have ever smoked—or 1,783 who have never smoked—would need to be screened to prevent 1 AAA-related death in the next 5 years. As always, clinicians must individualize recommendations depending on a patient's risk and likelihood of benefit. For example, some clinicians may choose to discuss screening with male nonsmokers nearing age 65 who have a strong first-degree family history of AAA that required surgery.
• The potential benefit of screening for AAA among women aged 65 to 75 is low because of the small number of AAA-related deaths in this population. The majority of deaths from AAA rupture occur in women aged 80 or older. Because there are many competing health risks at this age, any benefit of screening for AAA would be minimal. Individualization of care, however, is still required. For example, a clinician may choose to discuss screening in the unusual circumstance in which a healthy female smoker in her early 70s has a first-degree family history for AAA that required surgery.
• Operative mortality for open surgical repair of an AAA is 4 to 5 percent, and nearly one-third of patients undergoing this surgery have other important complications (e.g., cardiac and pulmonary). Additionally, men having this surgery are at increased risk for impotence.
• Endovascular repair of AAAs (EVAR) is currently being used as an alternative to open surgical repair. Although recent studies have shown a short-term mortality and morbidity benefit of EVAR compared with open surgical repair, the long-term effectiveness of EVAR to reduce AAA rupture and mortality is unknown. The long-term harms of EVAR include late conversion to open repair and aneurysmal rupture. EVAR performed with older-generation devices is reported to have an annual rate of rupture of 1 percent and conversion to open surgical repair of 2 percent. The conversion to open surgical repair is associated with a peri-operative mortality of about 24 percent. The long-term harms of newer generation EVAR devices are yet to be reported.
• For most men, 75 years may be considered an upper age limit for screening. Patients cannot benefit from screening and subsequent surgery unless they have a reasonable life expectancy. The increased presence of comorbidities for people aged 75 and older decreases the likelihood that they will benefit from screening.
• Ultrasonography has a sensitivity of 95 percent and specificity of nearly 100 percent when performed in a setting with adequate quality assurance. The absence of quality assurance is likely to lower test accuracy. Abdominal palpation has poor accuracy and is not an adequate screening test.
• One-time screening to detect an AAA using ultrasonography is sufficient. There is negligible health benefit in re-screening those who have normal aortic diameter on initial screening.
• Open surgical repair for an AAA of at least 5.5 cm leads to an estimated 43-percent reduction in AAA-specific mortality in older men who undergo screening. However, there is no current evidence that screening reduces all-cause mortality in this population.
• In men with intermediate-sized AAAs (4.0-5.4 cm), periodic surveillance offers comparable mortality benefit to routine elective surgery with the benefit of fewer operations. Although there is no evidence to support the effectiveness of any intervention in those with small AAAs (3.0-3.9 cm), there are expert opinion-based recommendations in favor of periodic repeat ultrasonography for these patients.

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Aspirin for the Primary Prevention of Cardiovascular Events

Summary of Recommendation The U.S. Preventive Services Task Force (USPSTF) strongly recommends that clinicians discuss aspirin chemoprevention with adults who are at increased risk for coronary heart disease (CHD). Discussions with patients should address both the potential benefits and harms of aspirin therapy. Grade: A Recommendation.

This USPSTF recommendation was first published in:  Ann Intern Med 2002;136(2):157-60.
To read the recommendation, go to: http://www.ahrq.gov/clinic/3rduspstf/aspirin/asprr.htm.

Clinical Considerations

• Decisions about aspirin therapy should take into account overall risk for coronary heart disease. Risk assessment should include asking about the presence and severity of the following risk factors: age, sex, diabetes, elevated total cholesterol levels, low levels of high-density lipoprotein (HDL) cholesterol, elevated blood pressure, family history (in younger adults), and smoking. Tools that incorporate specific information on multiple risk factors provide more accurate estimation of cardiovascular risk than categorizations based simply on counting the numbers of risk factors (www.intmed.mcw.edu/clincalc/heartrisk.html).¹⁶
• Men older than 40 years, postmenopausal women, and younger people with risk factors for CHD (e.g., hypertension, diabetes, or smoking) are at increased risk for heart disease and may wish to consider aspirin therapy. Table 2 shows how estimates of the type and magnitude of benefits and harms associated with aspirin therapy vary with an individual's underlying risk for coronary heart disease. Although balance of benefits and harms is most favorable in high-risk people (5-year risk > 3 percent), some people at lower risk may consider the potential benefits of aspirin to be sufficient to outweigh the potential harms.
• Discussions about aspirin therapy should focus on potential coronary heart disease benefits, such as prevention of myocardial infarction, and potential harms, such as gastrointestinal and intracranial bleeding. Discussions should take into account individual preferences and risk aversions concerning myocardial infarction, stroke, and gastrointestinal bleeding.
• Although the optimal timing and frequency of discussions related to aspirin therapy are unknown, reasonable options include every 5 years in middle-aged and older people or when other cardiovascular risk factors are detected.
• Most participants in the primary prevention trials of aspirin therapy have been men between 40 and 75 years of age. Current estimates of benefits and harms may not be as reliable for women and older men.
• Although older patients may derive greater benefits because they are at higher risk for CHD and stroke, their risk for bleeding may be higher.
• Uncontrolled hypertension may attenuate the benefits of aspirin in reducing CHD.
• The optimum dose of aspirin for chemoprevention is not known. Primary and secondary prevention trials have demonstrated benefits with a variety of regimens, including 75 mg per day, 100 mg per day, and 325 mg every other day. Doses of approximately 75 mg per day appear as effective as higher doses; whether doses below 75 mg per day are effective has not been established. Enteric-coated or buffered preparations do not clearly reduce adverse gastrointestinal effects of aspirin. Uncontrolled hypertension and concomitant use of other nonsteroidal anti-inflammatory agents or anticoagulants increase risk for serious bleeding.

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Screening for Carotid Artery Stenosis

Summary of Recommendation The U.S. Preventive Services Task Force (USPSTF) recommends against screening for asymptomatic carotid artery stenosis (CAS) in the general adult population. Grade: D Recommendation.

This USPSTF recommendation was first published in: Ann Intern Med. 2007;147:854-859.
To read the recommendation, go to: http://www.ahrq.gov/clinic/uspstf/uspsacas.htm

Clinical Considerations

• This recommendation applies to adults without neurological signs or symptoms, including a history of transient ischemic attacks or stroke. If otherwise eligible, an individual who has a carotid-area transient ischemic attack should be evaluated promptly for consideration of carotid endarterectomy.
• In a setting of excellent surgical care and low complication rates, screening may benefit patients who have a very high risk for stroke. It is not clear, however, how to identify people whose risk for stroke is high enough to justify screening, yet do not also have a high risk for surgical complications. The major risk factors for CAS include older age, male sex, hypertension, smoking, hypercholesterolemia, and heart disease.
• Available screening and confirmatory tests (duplex ultrasonography, digital subtraction angiography, and magnetic resonance angiography) all have imperfect sensitivity and appreciable harms. Therefore, screening could lead to non-indicated surgeries that result in serious harms, including death, stroke, and myocardial infarction, in some patients.
• In other recommendations, the USPSTF notes that adults should be screened for hypertension, hyperlipidemia, and smoking. In addition, clinicians should discuss aspirin chemoprevention for those who have an increased risk for cardiovascular disease. The evidence and recommendations for these conditions from the USPSTF are available on the AHRQ Web site at http://www.ahrq.gov/clinic/uspstfix.htm.

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Screening for Chronic Obstructive Pulmonary Disease

Summary of Recommendation The U.S. Preventive Services Task Force (USPSTF) recommends against screening adults for chronic obstructive pulmonary disease (COPD) using spirometry. Grade: D Recommendation.

This USPSTF recommendation was first published in: Ann Intern Med. 2008;148:529-534.
To read the recommendation, go to: http://www.ahrq.gov/clinic/uspstf/uspscopd.htm

Clinical Considerations

• This recommendation applies to healthy adults who do not recognize or report respiratory symptoms to a clinician. It does not apply to individuals with a family history of α1-antitrypsin deficiency. For individuals who present to clinicians reporting chronic cough, increased sputum production, wheezing, or dyspnea, spirometry would be indicated as a diagnostic test for COPD, asthma, and other pulmonary diseases.
  
• Screening for COPD would theoretically benefit adults with a high probability of severe airflow obstruction who might benefit from inhaled therapies. Risk factors for COPD include current or past tobacco use, exposure to occupational and environmental pollutants, and older age. However, even in groups with the greatest prevalence of airflow obstruction, hundreds of patients would need to be screened with spirometry to defer 1 exacerbation. For example, under the best-case assumptions about response to therapy, an estimated 455 adults between 60 and 69 years of age would need to be screened to defer 1 exacerbation.
• Spirometry can be performed in a primary care physician's office or in a pulmonary testing laboratory. The USPSTF did not review evidence comparing the accuracy of spirometry performed in the primary care versus referral settings.
  
• Regardless of the presence or absence of airflow obstruction, all current smokers should receive smoking cessation counseling and be offered pharmacologic therapies demonstrated to increase cessation rates. All patients 50 years of age or older should be offered influenza vaccine annually. All patients 65 years of age or older should be offered pneumococcal vaccine.

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Screening for Coronary Heart Disease

Summary of Recommendations The U.S. Preventive Services Task Force (USPSTF) recommends against routine screening with resting electrocardiography (ECG), exercise treadmill test (ETT), or electron-beam computerized tomography (EBCT) scanning for coronary calcium for either the presence of severe coronary artery stenosis (CAS) or the prediction of coronary heart disease (CHD) events in adults at low risk for CHD events. Grade: D Recommendation. The USPSTF found insufficient evidence to recommend for or against routine screening with ECG, ETT, or EBCT scanning for coronary calcium for either the presence of severe CAS or the prediction of CHD events in adults at increased risk for CHD events. Grade: I Statement.

This USPSTF recommendation was first published in:  Ann Intern Med 2004;140:569-72.
To read the recommendation, go to: http://www.ahrq.gov/clinic/3rduspstf/chd/chdrs.htm.

Clinical Considerations

• Several factors are associated with a higher risk for CHD events (the major ones are nonfatal myocardial infarction and coronary death), including older age, male gender, high blood pressure, smoking, abnormal lipid levels, diabetes, obesity, and sedentary lifestyle. A person's risk for CHD events can be estimated based on the presence of these factors. Calculators are available to ascertain a person's risk for having a CHD event; for example, a calculator to estimate a person's risk for a CHD event in the next 10 years can be accessed at http://hin.nhlbi.nih.gov/atpiii/calculator.asp?usertype=prof. Although the exact risk factors that constitute each of these categories (low or increased risk) have not been established, younger adults (i.e., men < 50 years and women < 60 years) who have no other risk factors for CHD (< 5 percent-10 percent 10-year risk) are considered to be at low risk. Older adults, or younger adults with 1 or more risk factors (> 15 percent-20 percent 10-year risk), are considered to be at increased risk.
• Screening with ECG, ETT, and EBCT could potentially reduce CHD events in 2 ways: either by detecting people at high risk for CHD events who could benefit from more aggressive risk factor modification, or by detecting people with existing severe CAS whose life could be prolonged by coronary artery bypass grafting (CABG) surgery. However, the evidence is inadequate to determine the extent to which people detected through screening in either situation would benefit from either type of intervention.
• The consequences of false-positive tests may potentially outweigh the benefits of screening. False-positive tests are common among asymptomatic adults, especially women, and may lead to unnecessary diagnostic testing, over-treatment, and labeling.
• Because the sensitivity of these tests is limited, screening could also result in false-negative results. A negative test does not rule out the presence of severe CAS or a future CHD event.
• For people in certain occupations, such as pilots and heavy equipment operators (for whom sudden incapacitation or sudden death may endanger the safety of others), considerations other than the health benefit to the individual patient may influence the decision to screen for CHD.
• Although some exercise programs initially screen asymptomatic participants with ETT, there is not enough evidence to determine the balance of benefits and harms of this practice.

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Screening for High Blood Pressure

Summary of Recommendation The U.S. Preventive Services Task Force (USPSTF) recommends screening for high blood pressure in adults aged 18 and older. Grade: A Recommendation.

This USPSTF recommendation was first published in: Ann Intern Med. 2007;147:787-791.
To read the recommendation, go to: http://www.ahrq.gov/clinic/uspstf/uspshype.htm.

Clinical Considerations

• This recommendation applies to adults without known hypertension.
• Office measurement of blood pressure is most commonly done with a sphygmomanometer. High blood pressure (hypertension) is usually defined in adults as a systolic blood pressure of 140 mmHg or higher, or a diastolic blood pressure of 90 mmHg or higher. Because of the variability in individual blood pressure measurements, it is recommended that hypertension be diagnosed only after 2 or more elevated readings are obtained on at least 2 visits over a period of 1 to several weeks.
• The relationship between systolic blood pressure and diastolic blood pressure and cardiovascular risk is continuous and graded. The actual level of blood pressure elevation should not be the sole factor in determining treatment. Clinicians should consider the patient's overall cardiovascular risk profile, including smoking, diabetes, abnormal blood lipid values, age, sex, sedentary lifestyle, and obesity, when making treatment decisions.
• Evidence is lacking to recommend an optimal interval for screening adults for hypertension. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) recommends screening every 2 years in persons with blood pressure less than 120/80 mmHg and every year with systolic blood pressure of 120 to 139 mmHg or diastolic blood pressure of 80 to 90 mmHg.⁷²
• Various pharmacological agents are available to treat high blood pressure. The JNC 7 guidelines for treatment of high blood pressure can be accessed athttp://www.nhlbi.nih.gov/guidelines/hypertension/jncintro.htm.
• Nonpharmacological therapies, such as reduction of dietary sodium intake, potassium supplementation, increased physical activity, weight loss, stress management, and reduction of alcohol intake, are associated with a reduction in blood pressure. For those who consume large amounts of alcohol (>20 drinks per week), studies have shown that reduced drinking decreases blood pressure.

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Screening for Lipid Disorders 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 by: Agency for Healthcare Research and Quality, Rockville, MD. June 2008.
To read the recommendation, go to: http://www.ahrq.gov/clinic/uspstf/uspschol.htm.

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Screening for Peripheral Arterial Disease

Summary of Recommendation The U.S. Preventive Services Task Force (USPSTF) recommends against routine screening for peripheral arterial disease (PAD). Grade: D Recommendation.

This recommendation statement was first published by: Agency for Healthcare Research and Quality, Rockville, MD. August 2005.
To read the recommendation, go to: http://www.ahrq.gov/clinic/uspstf05/pad/padrs.htm.

Clinical Considerations

• The ankle brachial index, a ratio of Doppler-recorded systolic pressures in the lower and upper extremities, is a simple and accurate noninvasive test for the screening and diagnosis of PAD. The ankle brachial index has demonstrated better accuracy than other methods of screening, including history-taking, questionnaires, and palpation of peripheral pulses. An ankle-brachial index value of less than 0.90 (95% sensitive and specific for angiographic PAD) is strongly associated with limitations in lower extremity functioning and physical activity tolerance.
• Smoking cessation and lipid-lowering agents improve claudication symptoms and lower extremity functioning among patients with symptomatic PAD. Smoking cessation and physical activity training also increase maximal walking distance among men with early PAD. Counseling for smoking cessation, however, should be offered to all patients who smoke, regardless of the presence of PAD. Similarly, physically inactive patients should be counseled to increase their physical activity, regardless of the presence of PAD.

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