Datasets:

marianna13
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litarch

+{"file": "es100_NBK164524/appf.nxml", "text": "Exclusion Codes\nE1: Study relevance\nE2: Population\nE2a: Patients with symptomatic PAD\nE2b: Exclusively persons with known CVD, diabetes\nE3: No relevant outcomes\nE4. Quality\nE4a. High or differential attrition\nE4b. Poor study quality: other quality issue\nE4c. Poor study quality: does not use reference standard\nE5: Setting: hospital, inpatient, LTC, vascular clinics\nE6. Not an included study design\nE6a. Study design: case control (applies to KQ2 only)\nE6b. Not an RCT, CCT, or SER\nE6c. Study design: CER\nE6d. Study design: followup from BL <3 months/12 weeks\nE6e. Does not adjust for traditional Framingham risk factors\nE7a. Not a study of ABI\nE7b. Not an included treatment", "pairs": [], "interleaved": []}
+{"file": "es100_NBK164524/appd.nxml", "text": "Appendix D displays the literature search results and article flow for the review. A total of 4,317 articles were identified through database searching and 117 articles were identified through other searching. 4,434 articles were screened after duplicates were removed. 418 full-text articles were assessed for eligibility. No articles were included for key question 1; 2 articles were included for key question 2; 1 article was included for key question 3; 16 articles were included for key question 4; 3 articles were included for key question 5; and 3 articles were included for key question 6.\nAbbreviations: ABI = ankle-brachial index; BL = baseline; CVD = cardiovascular disease; PAD = peripheral artery disease.", "pairs": [["litarch_figures_18/4d/97/es100_NBK164524/appdf1.jpg", "\nAbbreviations: ABI = ankle-brachial index; BL = baseline; CVD = cardiovascular disease; PAD = peripheral artery disease.\n", "Appendix D displays the literature search results and article flow for the review. A total of 4,317 articles were identified through database searching and 117 articles were identified through other searching. 4,434 articles were screened after duplicates were removed. 418 full-text articles were assessed for eligibility. No articles were included for key question 1; 2 articles were included for key question 2; 1 article was included for key question 3; 16 articles were included for key question 4; 3 articles were included for key question 5; and 3 articles were included for key question 6."]], "interleaved": [["litarch_figures_18/4d/97/es100_NBK164524/appdf1.jpg", "\nAbbreviations: ABI = ankle-brachial index; BL = baseline; CVD = cardiovascular disease; PAD = peripheral artery disease.\n", "Appendix D displays the literature search results and article flow for the review. A total of 4,317 articles were identified through database searching and 117 articles were identified through other searching. 4,434 articles were screened after duplicates were removed. 418 full-text articles were assessed for eligibility. No articles were included for key question 1; 2 articles were included for key question 2; 1 article was included for key question 3; 16 articles were included for key question 4; 3 articles were included for key question 5; and 3 articles were included for key question 6."], ["Abbreviations: ABI = ankle-brachial index; BL = baseline; CVD = cardiovascular disease; PAD = peripheral artery disease."]]}
+{"file": "es100_NBK164524/ch1.nxml", "text": "Scope and Purpose\nThe U.S. Preventive Services Task Force (USPSTF) will use this evidence review to update its previous recommendation on peripheral artery disease (PAD) screening. In 2005, the USPSTF recommended against routing screening for PAD based on fair-quality evidence indicating that routine screening for PAD in asymptomatic adults had little benefit (D recommendation).\nBackground\nDisease Definition\nPAD is an atherosclerotic occlusive condition in which plaque builds up in the distal arteries, constricting circulation and blood flow.1 PAD has also been referred to previously as peripheral vascular disease or peripheral artery occlusive disease. Lower-extremity PAD refers to atherosclerosis of arteries distal to the aortic bifurcation and most commonly occurs in the legs.2 The term PAD is also used more broadly to encompass a larger range of noncoronary arterial diseases or syndromes that are caused by the altered structure or function of arteries to the brain, visceral organs, and limbs.3 This review limits the definition of PAD, however, to atherosclerosis of the arteries distal to the aortic bifurcation, which is synonymous with lower-extremity PAD.\nClaudication is the most common symptom of lower-extremity PAD. Claudication is defined as discomfort, cramping, ache, or pain in one or both legs when walking that does not go away with continued walking and is relieved by rest. Most people with PAD, however, do not have any symptoms. Many people with PAD also have atypical manifestations of claudication or leg symptoms other than intermittent claudication, which further complicates diagnosis.3,4 Other signs and symptoms of PAD include foot pain at rest; numbness, tingling, cyanosis, hair loss, nonhealing ulcers, or gangrene of the lower extremity; functional impairment (e.g., poor standing balance, difficulty rising from a seated position); and erectile dysfunction.3,5,6\nPAD diagnosis relies on both anatomy and function because atherosclerosis in the relevant vessels is what leads to impaired or constricted blood flow. Guidelines do not specify the degree of stenosis or impaired blood flow that is clinically relevant. The gold standard for diagnosis is digital subtraction angiography (DSA), in which images taken before injection of contrast medium are subtracted from images taken after injection, leaving images of only the vessel itself. As an invasive procedure, DSA carries risks for nephrotoxic and hypersensitivity reactions to the contract medium, as well as for complications from arterial catheter access.7,8 Due to these risks, less invasive angiography (i.e., magnetic resonance angiography [MRA] and multirow detector computed tomography angiography [CTA]) are used in clinical practice, although the degree to which these tests have replaced DSA as the reference standard remains unclear. The resting ankle-brachial index (ABI) is the most commonly used test to screen and detect PAD in clinical settings. The ABI is the ratio of the systolic blood pressure measured over the ankle to the systolic blood pressure measured over the brachial artery.9 For many epidemiological studies, an abnormal ABI of less than 0.9 is often used to define PAD. It is important to note, however, that an abnormal ABI is not diagnostic for PAD.\nPrevalence and Burden of PAD\nStudies on the prevalence of PAD among general populations or unselected primary care populations use a low ABI as a surrogate for PAD. As such, the true prevalence of PAD in the general population is not known. The National Health and Nutrition Examination Survey (NHANES) provides recent data on the prevalence of low ABI (\u22640.9) from large, community-based sampling of the U.S. population. From 1999 to 2004, 5.9 percent of the U.S population age 40 years or older had a low ABI, which amounts to 7.1 million people.10 Excluding individuals with known coronary artery or cerebrovascular disease, 4.7 percent of the adult U.S. population had a low ABI.10 Similarly, another report that included data from seven U.S. population-based studies produced similar findings estimating that a total of 5.8 percent of the U.S. population age 40 years or older had a low ABI or history of lower-extremity revascularization, representing 6.8 million people.11\nThe prevalence of low ABI (\u22640.9) increases with age. About 1.9 percent of individuals ages 40 to 59 years have a low ABI, 8.1 percent among those ages 60 to 74 years have a low ABI, and 17.5 percent among those age 75 years and older have a low ABI.12 Although PAD is thought to be more common in men,11 the prevalence of low ABI does not appear to vary significantly by sex after adjusting for age.12-14 PAD prevalence also varies by race and ethnicity, with blacks having the highest age-adjusted prevalence of low ABI.11-15\nStudies have estimated that the mean annual inpatient and outpatient costs attributable to PAD for Medicare beneficiaries was $1,868 per PAD patient, representing a total of $4.37 billion in 2001.16 Placement of a vascular shunt, angioplasty, and lower-limb amputations were the most commonly performed procedures for PAD. A study of privately insured patients found the annualized PAD-related medical, hospital, outpatient, and pharmacy costs to be $5,995 per PAD patient in 1999\u20132003.17 A registry of patients with known PAD or low ABI found annual hospital costs ranged from $3,780 to $6,162 (depending on severity of disease) in 2003 to 2006.18\nEtiology and Natural History\nPAD is a manifestation of systemic atherosclerosis and is considered a predictor for other cardiovascular disease (CVD) (e.g., coronary artery disease [CAD] and cerebrovascular disease) and CVD events such as myocardial infarction (MI), cerebrovascular accident (CVA), and death.11 PAD is generally classified according to its clinical presentation:\nAsymptomatic (Rutherford Category 0; Fontaine Stage I)\nMild claudication (Rutherford Category 1; Fontaine Stage IIa)\nModerate claudication (Rutherford Category 2; Fontaine Stage IIb)\nSevere claudication (Rutherford Category 3; Fontaine Stage IIb)\nIschemic rest pain (Rutherford Category 4; Fontaine Stage III)\nMinor tissue loss (Rutherford Category 5)\nUlceration or gangrene (Rutherford Category 6; Fontaine Stage IV)\nTypically, 20 to 50 percent of persons with low ABI are asymptomatic. Of these, 40 to 50 percent exhibit atypical leg pain, 10 to 35 percent have claudication, and 1 to 2 percent have critical ischemia.3 Studies estimate that over a 5-year period, 70 to 80 percent of symptomatic persons without critical ischemia will have stable claudication, 10 to 20 percent will experience worsening claudication, and 1 to 2 percent will develop critical ischemia.3\nPatients with PAD have an increased risk of CVD events due to concomitant coronary and cerebrovascular disease. In general, persons with low ABI and/or claudication have similar risk of mortality due to CVD as patients with a history of CAD or cerebrovascular disease.9 Studies estimate that 20 percent of individuals with PAD will experience a nonfatal cardiovascular event and 15 to 30 percent will die within 5 years.3 Among patients with PAD, up to half have evidence of CAD (based on history or electrocardiography), 60 to 80 percent have serious CAD (of at least one vessel), and up to 25 percent have serious carotid artery disease (diagnosed by duplex ultrasound).3 Both CAD and cerebrovascular disease are significantly associated with low ABI (\u22640.9).19,20 A low ABI is also associated with unrecognized subclinical CVD (i.e., diagnosed by electrocardiography, echocardiography, exercise stress test, MRA, or carotid duplex ultrasound).21-23\nThe extent of atherosclerosis, acuity of limb ischemia, and ability to restore arterial circulation determine the prognosis of the lower extremity in patients with PAD.3 For patients with chronic atherosclerosis and progression to symptoms of chronic limb ischemia, for example, prognosis of the affected limb is very poor unless it can be revascularized. For patients with acute occlusive events (i.e., thromboembolic occlusion with little underlying atherosclerosis), on the other hand, the prognosis of the limb is related to the rapidity and completeness of revascularization before the onset of irreversible ischemic tissue damage.3\nRisk Factors\nIn addition to increasing age, major risk factors for PAD include diabetes, smoking, hypertension, high cholesterol, obesity, and physical inactivity.16,24 The estimated prevalence of low ABI is about 7.6 to 9.6 percent in adults with diabetes, 5.5 percent in smokers, 6.7 to 7.6 percent in adults with hypertension, 4.6 to 5.6 percent in adults with hypercholesterolemia, and 5.3 to 5.7 percent in adults with a body mass index (BMI) over 30 kg/m2.15,25 Several studies in primary care or general populations have shown significant associations between most of these risk factors and low ABI in multivariable analyses.19,26-30 Smoking and diabetes show the strongest association with low ABI in most multivariable analyses; smoking has odds ratios (ORs) ranging from 1.55 (95% confidence interval [CI], 1.34 to 1.79)28 to 5.35 (95% CI, 1.77 to 16.22)26 and diabetes has ORs ranging from 1.59 (95% CI, 1.00 to 2.51)30 to 3.8 (95% CI, 1.6 to 9.0).27 An estimated 80 percent of persons with PAD are current or former smokers, and 12 to 20 percent of persons with PAD have diabetes.16\nRationale for Screening\nPAD is an important manifestation of systemic atherosclerosis. Therefore, screening for PAD in asymptomatic persons may lead to early CVD risk factor modification in persons with undiagnosed atherosclerosis. In addition, PAD has been underdiagnosed and undertreated compared with other types of CVD because the majority of patients with PAD do not have symptoms or have atypical symptoms.31 Taking a patient's clinical history alone is not a sufficient screening method for PAD, as less than 10 percent of community-dwelling adults with PAD report having classic symptoms (such as intermittent claudication) and up to 48 percent report no symptoms at all.32 Likewise, a physical examination has limited value for screening asymptomatic persons, as only a femoral bruit, a pulse abnormality, or skin changes significantly increase the likelihood ratio for low ABI (\u22640.9) and all these signs indicate moderate to severe disease.32\nIn many epidemiologic surveys, population-based diagnosis and classification have used standardized questionnaires, most commonly the World Health Organization Rose questionnaire or the Edinburgh Modification of the Rose questionnaire. The Walking Impairment Questionnaire and the San Diego claudication questionnaire are more recently developed questionnaires designed to screen for PAD with greater sensitivity and specificity.3 These questionnaires, however, only detect persons with symptoms.\nThe resting ABI is the most commonly used test to screen for and detect PAD in clinical settings. The ABI is the ratio of the systolic blood pressure measured over the ankle to the systolic blood pressure measured over the brachial artery.9 The systolic blood pressure is measured after the patient has rested for 5 to 10 minutes and is in the supine position,33 using a manual sphygmomanometer and a handheld Doppler ultrasound probe, 34 although specific techniques vary. This variation in protocols of measurement may lead to differences in the ABI values obtained.25,35,36 Overall, the ABI is considered to have good reproducibility (variance of about 0.10).3\nTraditionally, ABI values of 1.00 to 1.29 are considered normal. ABI values of 0.00 to 0.40 indicate severe PAD, 0.41 to 0.90 indicate mild to moderate PAD, 0.91 to 0.99 are considered borderline, and greater than 1.30 indicates noncompressible arteries.3 Recent recommendations state that ABI values greater than 1.40 indicate noncompressible arteries and that 1.00 to 1.40 be considered normal.6\nThe prevalence of abnormal ABI in primary care varies depending on the population's age and CVD risk profile. Prevalence of low ABI (\u22640.9) is as low as 2 percent, for example, among adults younger than age 60 years or populations without known CVD.12,26 This prevalence increases dramatically, however, with older age and increased cardiovascular risk factors. For example, the prevalence of a low ABI was 29 percent in a national sample of 6,979 people who were age 70 years or older or ages 50 to 69 years with a history of smoking or diabetes.37\nThe prevalence of noncompressible arteries (ABI >1.30 or 1.40) is generally low. Among the NHANES cohort, 3.6 percent had an ABI greater than 1.3012 and 1.5 percent had an ABI greater than 1.40.10 In other community-based cohorts, 3.9 to 5.5 percent had an ABI greater than 1.30 and 1.1 to 1.2 percent had an ABI greater than 1.40.38,39 The prevalence of noncompressible arteries also increases with age and CVD risk factors. For example, in the United States, 6.3 percent of clinic patients who were older than age 70 years, or those who were ages 50 to 69 years with CVD risk factors, had an ABI greater than 1.40.40 While the clinical implications of a high ABI (>1.30 or 1.40) are uncertain, persons with a high ABI are generally older and more likely to have CVD risk factors, particularly diabetes and hypertension.39-41 Persons with noncompressible arteries who are suspected of having PAD usually go on to additional diagnostic testing.\nThere are multiple other noninvasive vascular diagnostic techniques, including the toe-brachial index, segmental pressure measurements, pulse volume recordings, duplex ultrasound imaging, Doppler waveform analysis, and exercise/treadmill testing.3 The toe-brachial index is used for patients with suspected PAD who have noncompressible arteries at the ankle. Studies have suggested segmental pressure examination and duplex ultrasound represent noninvasive methods for followup diagnostic testing in symptomatic persons with suspected PAD who have a normal (or supranormal) ABI value.3 Other testing may be useful in the diagnostic workup, assessment of prognosis, or monitoring therapy for PAD. MRA, CTA, and invasive angiographic techniques are generally reserved for further workup of PAD in persons with symptoms for whom revascularization may be an option.\nIn addition to its ability to detect PAD, an abnormal ABI may be useful for predicting CVD morbidity and mortality. Like other CVD risk factors or CAD risk equivalents, ABI measurement may increase existing CVD risk assessments' discrimination or calibration. Currently, the Adult Treatment Panel (ATP) III of the National Cholesterol Education Program algorithm is the most widely used system for categorizing CAD risk in the United States.42 This sex-specific algorithm uses the traditional Framingham risk factors (sex, age, total cholesterol, high-density lipoprotein [HDL] cholesterol, smoking status, and systolic blood pressure) to stratify individuals who do not have established atherosclerosis or diabetes into three risk categories for developing CAD events.43 Low-risk individuals have less than a 10 percent risk of developing CAD events over 10 years, intermediate-risk individuals have a 10 to 20 percent risk, and high-risk individuals have more than a 20 percent risk.42 While ATP III is widely used, it was developed in 2001 and will soon be updated.44 Additionally, the ATP III focuses on predicting hard CAD events (as opposed to global CVD events). While the Framingham risk score (FRS) generally provides good discrimination for future morbidity and mortality, it is still imperfect (c-statistic can range from 0.60 to 0.80) and may not perform as well in nonblack minorities.45-50 Other risk prediction scores have since been developed, validated, and used to predict global CVD events, including the Framingham global CVD score,51 QRISK2,52,53 and the Reynolds risk score.54,55 In clinical practice, these risk prediction tools help guide the type and intensity of management of risk factor modification and will help practitioners communicate risk with patients.\nInterventions/Treatment\nThe primary aims of treating PAD itself, or treating PAD as a manifestation of systemic atherosclerosis, are to reduce overall CVD morbidity (e.g., MI, CVA), decrease PAD morbidity (e.g., increase walking distance and quality of life by improving symptoms of intermittent claudication and leg function, prevent or reduce limb complications, and preserve limb viability), and decrease mortality, while minimizing the harms of treatment. Treating PAD can be categorized into measures to reduce CVD risk, medical treatment of PAD symptoms (e.g., claudication), and revascularization of the lower extremities.\nCVD risk reduction includes smoking cessation, cholesterol lowering, glycemic control, weight reduction, blood pressure control, and antiplatelet therapy. Medical treatment of symptoms includes pharmacologic (i.e., pentoxifylline, cilostazol) and nonpharmacologic (i.e., exercise therapy) interventions. Revascularization by angioplasty, thrombolysis, stenting, or bypass surgery is reserved for persons with severe PAD who are severely disabled by claudication or have acute or critical limb ischemia or by thrombolysis for persons with acute limb ischemia.8,56 Because this review focuses on screening for PAD in asymptomatic persons, our review of treatment options focuses on CVD risk reduction.\nCurrent Clinical Practice\nThe American College of Cardiology Foundation/American Heart Association (ACCF/AHA) practice guidelines recommend resting ABI testing for detecting PAD among patients at increased risk, including those age 65 years or older, those age 50 years or older with a history of smoking or diabetes, or those of any age with exertional leg symptoms or nonhealing wounds.6,57 In their 2010 \u201cGuideline for Assessment of Cardiovascular Risk in Asymptomatic Adults,\u201d the ACCF/AHA also recommended the ABI as a reasonable tool for cardiovascular risk assessment among patients at intermediate risk.57 A survey of primary care practices across the United States, however, found that nearly 70 percent of providers reported never using ABI in their practice settings, 6 to 8 percent reported using ABI annually, while 12 to 13 percent reported using ABI weekly or monthly.58\nAdministering the ABI takes about 15 minutes in primary care practices.3 ABI alone, however, is usually not reimbursed by health care payers, as they require documentation that might be obtained using pulse volume recordings or Doppler waveform tracings.3\nPrevious USPSTF Recommendations\nIn 2005, the USPSTF recommended against routine screening for PAD (D recommendation),59,60 which was unchanged from the 1996 recommendation.61 Previously, the USPSTF concluded that there was fair evidence that screening with ABI can detect adults with asymptomatic PAD. Screening for PAD among asymptomatic adults in the general population, however, would have few or no benefits because the prevalence of PAD in this group is low and there was little evidence that treating PAD at the asymptomatic stage improves health outcomes beyond treatment based on standard CVD risk assessment.60\nThe review to support the 2005 recommendation62 was a targeted review that included only three studies.63-65 The review concluded that while evidence exists to support the use of physical activity and smoking cessation to improve outcomes in early PAD (one trial), these interventions are already offered to all patients and do not necessarily offer additional benefit to persons with screen-detected PAD.60 This review, however, had a very limited scope. First, the review focused on outcomes of lower-extremity symptoms and function, rather than outcomes related to CAD or other CVD. The review did not examine PAD as a risk factor for CAD. Second, the review used a literature search strategy that was probably not comprehensive. A commentary in response to the 2005 USPSTF recommendation on screening for PAD stated that the evidence review did not include three large studies of the prevalence of PAD in primary care.66 Third, the 2005 review searched from 1994 to update the 1996 recommendation. The 1996 recommendation, however, was not based on systematically reviewed evidence.61\nAdditionally, in 2009, the USPSTF found insufficient evidence to assess the balance of benefits and harms of using nontraditional risk factors, including ABI, to screen asymptomatic men and women with no history of coronary heart disease (CHD) to prevent CHD events.67 Other nontraditional risk factors included in this recommendation were high-sensitivity C-reactive protein, leukocyte count, fasting blood glucose level, periodontal disease, carotid intima-media thickness, coronary artery calcification score on electron-beam computed tomography, homocysteine level, and lipoprotein(a) level.\nOur evidence review, therefore, addresses overall net benefit of screening for PAD in unselected populations or in generally asymptomatic populations.", "pairs": [], "interleaved": []}