Note: This draft Recommendation Statement is not the final recommendation of the U.S. Preventive Services Task Force. This draft is distributed solely for the purpose of pre-release review. It has not been disseminated otherwise by the USPSTF. It does not represent and should not be interpreted to represent a USPSTF determination or policy.
This draft Recommendation Statement is based on an Evidence Report that was also available for public comment. To read the accompanying draft Evidence Report on Screening for Peripheral Artery Disease and Cardiovascular Disease Risk Assessment With Ankle Brachial Index in Adults, go to http://www.uspreventiveservicestaskforce.org/uspstf12/pad/paddraftrep.htm.
The USPSTF makes recommendations about the effectiveness of specific clinical preventive services for patients without related signs or symptoms.
It bases its recommendations on the evidence of both the benefits and harms of the service, and an assessment of the balance. The USPSTF does not consider the costs of providing a service in this assessment.
The USPSTF recognizes that clinical decisions involve more considerations than evidence alone. Clinicians should understand the evidence but individualize decisionmaking to the specific patient or situation. Similarly, the USPSTF notes that policy and coverage decisions involve considerations in addition to the evidence of clinical benefits and harms.
This draft Recommendation Statement was available for comment from March 19 until April 15, 2013, at 5:00 PM ET. A fact sheet that explains the draft recommendations in plain language is available here.
Screening for Peripheral Artery Disease and Cardiovascular Disease Risk Assessment With Ankle Brachial Index in Adults: U.S. Preventive Services Task Force Recommendation Statement
Summary of Recommendation and Evidence
The U.S. Preventive Services Task Force (USPSTF) concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for peripheral artery disease (PAD) and cardiovascular disease (CVD) risk assessment with ankle brachial index (ABI) in adults.
This is an I statement.
Go to the Clinical Considerations section for additional information about suggestions for practice regarding the I statement.
In addition to morbidity directly caused by PAD, patients with PAD have an increased risk of CVD events due to concomitant coronary and cerebrovascular disease. Recent data on the prevalence of low ABI (≤0.9) from the National Health and Nutrition Examination Survey (NHANES) show that 5.9% of the U.S. population age 40 years and older (7.1 million people) have a low ABI (1). More than half of people with a low ABI do not exhibit typical symptoms of PAD.
Early detection of PAD in asymptomatic patients is primarily considered because subsequent treatment may reduce CVD in a potentially large group of individuals who are otherwise not known to be at increased CVD risk. Patients with known CVD or diabetes are already at high risk for future CVD events, and risk reduction interventions are recommended for these patients (e.g., antiplatelet therapy, low-density lipoprotein [LDL] cholesterol lowering with statins). PAD screening with ABI in individuals with diabetes or known CVD is unlikely to alter effective management decisions and is therefore outside the scope of this recommendation.
While the USPSTF found little data on the reliability of ABI as a screening test in asymptomatic persons, it was able to extrapolate from evidence in symptomatic adults and conclude that there is adequate evidence that ABI is a reliable screening test for PAD.
Benefits of Detection and Early Treatment
The USPSTF found no evidence that screening for and treatment of PAD in asymptomatic patients leads to clinically important benefits. It also reviewed the potential benefit of adding ABI to Framingham Risk Score (FRS) results and found evidence that it results in some patient risk reclassification; however, it is unknown how often the reclassification is appropriate or if it results in improved clinical outcomes.
One randomized trial found that aspirin did not reduce CVD events in patients with low ABI (2). No studies have assessed the impact of lipid-lowering therapy or other cardiovascular risk reduction interventions in patients with asymptomatic PAD and without known CVD or diabetes. The USPSTF found inadequate evidence that early treatment of screen-detected PAD leads to improvement in clinical outcomes.
Harms of Detection and Early Treatment
The USPSTF found no studies addressing the magnitude of harms of screening for PAD with ABI; however, the direct harms to the patient of screening itself, beyond the time needed to obtain the test, are likely to be minimal. Other harms resulting from testing may include false-positive results, exposure to gadolinium or contrast dye if either magnetic resonance angiography (MRA) or computed tomography angiography (CTA) is used to confirm diagnosis, anxiety, labeling, and opportunity cost.
There is inadequate evidence to assess the harms of early treatment of screen-detected PAD. One study showed that low-dose aspirin treatment in asymptomatic patients with low ABI may increase bleeding (2). Additional harms associated with treatment include use of unnecessary medications (or higher doses) with their resultant adverse effects and discontinuation of medications known to be effective in patients with established coronary artery disease (CAD) if the patient is reclassified to a lower risk category based on a normal ABI.
Patient Population Under Consideration
This recommendation applies to asymptomatic adults who do not have a known diagnosis of PAD, CVD, severe chronic kidney disease, or diabetes.
Assessment of Risk
In addition to increasing age, major risk factors for PAD include diabetes, smoking, hypertension, high cholesterol, obesity, and physical inactivity, with smoking and diabetes showing the strongest association (3). PAD is more common in men than women and occurs at an earlier age in men than women, possibly in part due to the higher prevalence of smoking in men. Among healthy U.S. men ages 40 to 75 years without a history of CVD, the risk of PAD over 25 years of followup in the absence of four conventional cardiovascular risk factors (smoking, hypertension, hypercholesterolemia, or type 2 diabetes) is rare (9 cases per 100,000 person-years) (4). These four risk factors account for 75% of all cases of PAD, and at least one risk factor is present at the time of PAD diagnosis in 96% of men. Therefore, if screening is determined to be beneficial, it is likely to be among individuals at increased risk for PAD who are not already receiving cardiovascular risk reducing interventions.
PAD is a manifestation of systemic atherosclerosis and is typically considered a predictor for other types of CVD (e.g., CAD, cerebrovascular disease) and CVD events, such as myocardial infarction (MI), cerebrovascular accident (CVA), and death. Patients with PAD have an increased risk of CVD events due to concomitant coronary and cerebrovascular disease (5).
Screening tests. Resting ABI is the most commonly used test to screen for and detect PAD in clinical settings, although variation in measurement protocols may lead to differences in ABI values obtained. ABI is determined by the systolic blood pressure obtained at the ankle divided by the systolic blood pressure obtained at the brachial artery, while the patient is lying down. A ratio less than 1 (typically defined as <0.9) is considered abnormal and is commonly used to define PAD. Physical examination has low sensitivity for detecting mild PAD in asymptomatic persons. While femoral bruit, pulse abnormalities, or ischemic skin changes significantly increase the likelihood ratio for low ABI (≤0.9), these signs indicate moderate to severe obstruction and/or clinical signs of disease. While often performed, the clinical benefits and harms of PAD screening with a physical examination have not been well evaluated and are beyond the scope of this review (5).
In addition to its ability to detect PAD, an abnormal ABI may be a useful predictor of future CVD morbidity and mortality. ABI measurement may increase existing CVD risk assessments' discrimination or calibration apart from whether or not it accurately detects PAD. However, it is unclear how many patients with an abnormal ABI also have other diseases or findings that would indicate treatment and whether there is value to knowing their ABI.
Screening intervals. There were no studies that provided evidence about the intervals for screening with ABI.
Treatment. There is evidence that low-dose aspirin treatment in asymptomatic patients with low ABI does not improve health outcomes and may increase bleeding (2). There is no trial evidence, however, on other interventions to reduce CVD events or interventions that might delay the onset of lower extremity symptoms.
Suggestions for Practice Regarding the I Statement
In deciding whether to screen for PAD with ABI in asymptomatic adults, clinicians should consider the following.
Potential preventable burden. The true prevalence of PAD in the general population is not known. Recent data on the prevalence of low ABI (≤0.9) from the NHANES show that 5.9% of the U.S. population age 40 years and older (7.1 million people) have a low ABI (1). More than half of people with a low ABI do not exhibit typical symptoms of PAD. No information is available on what proportion of these patients will go on to develop symptoms; however, PAD is an indicator of CVD. Studies estimate that over 5 years among persons with stable claudication but not critical ischemia, approximately 70% to 80% will remain stable, while 10% to 20% will experience worsening claudication and 1% to 2% will develop critical ischemia (6). Similar data are not available for asymptomatic patients with a low ABI.
Potential harms. While there are minimal harms associated with the ABI procedure itself, there are possible downstream harms. False-positive results, anxiety, labeling, and exposure to gadolinium or contrast dye if either MRA or CTA is used for confirmation of the diagnosis may occur. Use of ABI in conjunction with FRS has the potential to reclassify individuals. Given the uncertainty of the appropriateness of such reclassifications, this could result in patients either being reclassified to a higher risk category and receiving additional treatments, with the resultant adverse effects, or being reclassified to a lower risk category and discontinuing treatments that might be beneficial (5).
Cost. The cost of performing ABI is mainly in time and staff resources, as it takes approximately 15 minutes to perform the test in the office setting (6). Additionally, new equipment that performs pulse volume recordings or Doppler wave form tracings may need to be purchased (6).
Provision of this test to asymptomatic individuals may divert time away from other prevention activities that might be more beneficial to that particular patient.
Current practice. A survey of primary care practices across the United States found that nearly 70% of providers report never using ABI in their practice settings, 6% to 8% report using ABI once a year, and only 12% to 13% report using ABI weekly or monthly (7).
Research Needs and Gaps
A large population-based, randomized trial is needed to determine if screening for PAD with ABI improves clinical outcomes. One ongoing study in Denmark expects to publish results after 2018. However, this study limited enrollment to men ages 65 to 74 years and also includes screening for abdominal aortic aneurysm. Thus, the role of ABI screening alone or in women and younger men is not addressed by this study. Future studies should address the large population of individuals at potentially increased risk for PAD who are not already receiving cardiovascular risk reduction interventions.
Clarity of language around describing PAD is important for researchers and clinicians. A low ABI appears to be a valid measure of PAD, although further verification studies with more diverse populations would be useful. More evidence is needed on how many persons will develop clinical signs or symptoms in their lifetime and the risk of overdiagnosis. Additionally, it is not clear if it is more worthwhile to identify and treat asymptomatic individuals with screen-detected PAD compared to targeting identification to individuals with signs or symptoms of disease or other manifestations of CVD or CVD risk equivalents (e.g., diabetes).
Intervention studies of individuals with screen-detected PAD or those who have been risk reclassified solely on the basis of ABI are needed to determine if treatment initiation, modification, or intensification among patients with asymptomatic PAD who have no other indications for interventions (e.g., lipid levels, blood pressure, antiplatelet therapy) improves clinical outcomes.
Because risk prediction for CAD and CVD continues to evolve, expected updates to Adult Treatment Panel (ATP) III criteria in 2013, along with ongoing studies or reanalysis of existing population-based cohorts will be critical to the understanding of the value of ABI screening to reclassify CAD and CVD risk within the current FRS system and other risk prediction models. An update of the ABI Collaboration analysis using the net reclassification index (NRI) is also currently underway.
Evaluation of the relative value of ABI screening within certain subgroups (e.g., persons with higher underlying prevalence of low ABI, those in whom traditional risk prediction does not perform well, or those near thresholds of risk categories) may help in the discrimination and calibration of existing models.
Finally, further study is needed to determine whether aggressive risk factor modification in patients with multiple atherosclerotic risk factors can reduce the incidence of symptomatic PAD.
Burden of Disease
The most recent data from 1999 to 2004 show that 5.9% of adults age 40 years and older in the United States have a low ABI. In the United States, a low ABI (typically <0.9) is used as a marker for PAD. However, there is limited evidence that it is an accurate screening test in asymptomatic adults, so the actual prevalence of PAD is unknown. When individuals with known CAD or cerebrovascular disease are excluded, the prevalence of PAD is 4.7% (1). The burden of disease is higher in older populations; the prevalence of low ABI in adults ages 40 to 59 years is 1.9%. The percentage rises to 8.1% in adults ages 60 to 74 years, and up to 17.5% in those age 75 years and older. PAD is a manifestation of systemic atherosclerosis and is considered a predictor for other atherosclerotic CVD and CVD events. The natural history of screen-detected PAD, including the development of morbidity and mortality directly related to lower extremity atherosclerosis, is not well known. Thus, the true burden of asymptomatic, screen-detected PAD is difficult to determine.
Scope of Review
This topic was previously reviewed by the USPSTF in 2005. It recommended against screening for PAD (D recommendation), which was unchanged from the recommendation issued in 1996. The 2005 review was very limited, focusing only on lower extremity symptoms and function. It did not address PAD as a predictor for CVD. In 2009, the USPSTF assessed the use of nontraditional risk factors, including ABI, to predict coronary heart disease events, and determined that the evidence was insufficient to assess the balance of benefits and harms (I statement) (8).
The current review includes broader CVD outcomes than the previous reviews and specifically focuses on: 1) resting ABI testing as the only screening modality; 2) the diagnostic performance of ABI testing in primary care populations, unselected populations, and/or asymptomatic populations; 3) the predictive value of ABI testing in primary care or unselected populations for major CVD outcomes; and 4) the treatment of patients with asymptomatic or minimally symptomatic PAD impacting both general CVD morbidity and PAD-specific (lower extremity) morbidity (5). The review evaluated studies published from 1996 through September 2012 that used resting ABI as a screening test for PAD or as a risk predictor for CVD. As described above, PAD screening with ABI in individuals with diabetes or known CVD is unlikely to alter effective management decisions and is outside the scope of this recommendation. Additionally, while often performed, the clinical benefits and harms of PAD screening with a physical examination have not been well evaluated and are beyond the scope of this review.
Accuracy of Screening Tests
In practice, a low ABI is used as a surrogate marker for PAD; however, little information is available about its accuracy as a screening tool for PAD in asymptomatic, primary care populations. Only one fair-quality study was found that evaluated its use in a relevant population; however, the study did have some limitations (9). It was conducted in Sweden, included 306 people, and all participants were age 70 years upon entry to the study. Additionally, the mean interval between ABI and MRA was 16 months. Using whole body MRA showing at least 50% stenosis in the pelvic or lower extremity arteries as the reference standard, an ABI of <0.9 had sensitivity of 15% to 20% but specificity of 99%. Despite its low sensitivity, the positive and negative predictive values for ABI in this study were 82% to 83% and 80% to 84%, respectively. Even though the study had significant limitations, after extrapolating from evidence in symptomatic populations, the USPSTF felt there was adequate evidence that ABI is a reliable screening test for PAD in asymptomatic populations.
Effectiveness of Early Detection and/or Treatment
Early detection. No studies were found that directly addressed the impact of screening for PAD with ABI on future cardiovascular morbidity and/or mortality or PAD-related outcomes. There was one meta-analysis and 14 additional fair- to good-quality studies addressing whether ABI is predictive of CAD or CVD morbidity and mortality, independent of FRS risk factors (5). Included studies evaluated the added prognostic value of ABI to FRS risk factors (age, sex, smoking status, systolic blood pressure, total cholesterol, and high-density lipoprotein cholesterol). One large, individual patient-level meta-analysis (n=48,294) from the ABI Collaboration contributed the most evidence (10).
Overall, data from 52,510 individuals across 18 different population-based cohort studies demonstrated that low ABI (≤0.9) is associated with future CAD and CVD events, independent of FRS factors. The ABI Collaboration meta-analysis found that including ABI with FRS risk factors resulted in the reclassification of 19% of men and 36% of women into different risk categories (10). The majority of reclassifications for men reclassified those at high risk with normal ABI into the intermediate category, while for women they reclassified those at low risk with low ABI into intermediate and high risk categories.
Several issues, however, limit the interpretation of these findings. The proportion of individuals who were appropriately reclassified is not known. The ABI Collaboration meta-analysis was done before NRI became commonly used in research studies. NRI is a measure of the proportion of cases reclassified into different categories, based on the addition of a risk factor to the assessment, that are appropriately reclassified. Another issue is that the ABI Collaborative reclassification is based on total CAD events (CAD death, MI, or angina), while the ATP III FRS algorithm uses only hard CAD events (CAD death and MI only). Additionally, the reclassification of men was based on small changes in the 10-year risk, which may not be clinically important if there is imprecision in the measurement of the risk or if different definitions are used for risk categories. The ABI Collaborative used a different definition of normal ABI (1.1–1.4 instead of 0.9–1.4) than is typically used, which could exaggerate the risk compared to studies using the typical definition. The more common definition of 0.9 as a low ABI leads to a greater proportion of men being reclassified (35%) and a lower proportion of women (7%), though in the same direction.
Four cohort studies used NRI to determine appropriateness of reclassification using ABI in addition to FRS risk factors and reported small or nonstatistically significant NRIs (11-14). It is difficult to make comparisons between these four studies and the ABI Collaboration meta-analysis due to differences in populations (e.g., age, sex, race/ethnicity), choice of referent group (i.e., definition of normal ABI), definitions of composite CAD outcomes (i.e., hard vs. total CAD) and risk categories (e.g., intermediate risk of 10% to 19%, 15% to 25%, or 5% to 20%), and measures of reclassification (i.e., number reclassified vs. NRI). These differences prevent analysis of consistency across the populations; however, the studies suggest that NRI is relatively small, though it may be higher for older populations.
Treatment. Two studies were found that address treatment of asymptomatic patients with low ABI or PAD. The first, Aspirin for Asymptomatic Atherosclerosis (AAA), was a large, good-quality, randomized, controlled trial that addressed whether asymptomatic men and women ages 50 to 75 years with screen-detected low ABI would benefit from daily aspirin therapy (2). There were 28,980 participants screened and 17% (n=4,914) had an ABI of 0.95 or lower. Of those, 3,350 were randomly assigned to aspirin therapy (100 mg/day) or placebo. The study had a mean followup of 8.2 years and did not demonstrate any significant difference in CVD events (MI, CVA, or revascularization) between the two groups (hazard ratio [HR], 1.03 [95% CI, 0.84 to 1.27]). In the subset of patients with an ABI of 0.9 or lower, there was also not a significant difference between the aspirin and placebo groups. Additionally, there were no significant differences in either secondary outcome—CVD events plus angina, intermittent claudication, or transient ischemic attack—or all-cause mortality.
The second study investigated whether patients with PAD and high LDL cholesterol could improve lipid control with an intensive telephone counseling intervention (15). The majority of patients in this trial conducted at two U.S. medical centers had no or atypical symptoms (20.3% and 54.5%, respectively), and the minority of patients had intermittent claudication (15.2%). Patients had an average ABI of 0.68 and an average LDL cholesterol level of 183 mg/dL. Three groups were compared: intervention, attention control, and usual care. The intervention group received telephone calls every 6 weeks (total of 200 minutes) focusing on the importance of lowering LDL cholesterol, adherence to medication, communicating with their treating physician about needing more intensive therapy, and increasing walking activity; in addition, study staff sent a letter to the treating physician after each call. The attention control group received telephone calls with general PAD information and the usual care group received no calls. At 12 months of followup, the intervention group had a significantly greater decrease in LDL cholesterol than the attention control group but not the usual care group; however, a greater proportion of participants in the intervention group achieved LDL cholesterol levels below 100 mg/dL than in either of the other two groups.
After considering these two studies, as well as the lack of studies evaluating the impact of other cardiovascular risk reduction interventions, such as lipid-lowering therapy, the USPSTF determined there is inadequate evidence that early treatment of screen-detected PAD leads to improvement in clinical outcomes.
Potential Harms of Screening and/or Treatment
No studies directly addressed the harms of screening individuals for PAD with ABI. The harms to the patient of the screening test itself, beyond the time needed to obtain the test, are likely to be minimal. Other harms resulting from testing may include false-positive results, exposure to gadolinium or contrast dye if either MRA or CTA is used to confirm diagnosis, anxiety, labeling, and opportunity cost. The time and resources needed to screen a patient with ABI in a primary care setting may detract from other prevention activities that may have more benefit.
The only study that addressed the harms of treatment of asymptomatic individuals was the good-quality AAA trial, previously discussed, which compared daily aspirin therapy to a placebo control. In this trial, participants randomly assigned to the aspirin therapy group had a nonsignificant trend toward increased major bleeding events requiring hospitalization than those in the placebo group (HR, 1.71 [95% CI, 0.99 to 2.97]) (2). No studies addressed the harms of other potential treatments, such as cholesterol-lowering medications or smoking cessation.
Estimate of Magnitude of Net Benefit
The USPSTF found adequate evidence that ABI is a reliable screening test for PAD (based almost exclusively on information in symptomatic adults) and that a low ABI (≤0.9) is associated with future CAD and CVD events, independent of FRS factors. Additionally, using ABI with regular FRS risk factors did result in reclassification of individuals into different risk groups, although the appropriateness of the reclassifications could not be assessed. Studies addressing the benefits of treatment are sparse, with one good-quality study showing no benefit to daily aspirin therapy compared to placebo control. No studies evaluated whether treatments initiated because of risk reclassification due to ABI findings result in benefit to reclassified asymptomatic patients. Additionally, no studies addressed harms of screening, although the potential exists for overdiagnosis, labeling, and opportunity cost. The one study that addressed the harms of treatment evaluated daily aspirin therapy and showed a nonsignificant trend toward increased risk for major bleeding. Therefore, the USPSTF concludes that evidence on the balance of benefits and harms of screening is lacking.
How Does Evidence Fit With Biological Understanding?
PAD is generally considered to be a manifestation of systemic atherosclerosis. Detection of this condition when a patient is asymptomatic may also suggest that the patient has significant atherosclerosis in other vessels, such as the heart or brain, and therefore may be at risk for types of CVD other than PAD. Early detection and intervention to reduce atherosclerotic progression and prevent future CVD events could improve health outcomes compared to intervention strategies employed in the absence of PAD screening. However, a substantial number of individuals with asymptomatic low ABI may never develop clinical signs or symptoms of CVD, and therefore would be at risk for the harms of testing and subsequent treatments.
Recommendations of Other Groups
The 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 and older, those age 50 years and older with a history of smoking or diabetes, and those of any age with exertional leg symptoms or nonhealing wounds (16). In their 2010 “Guideline for Assessment of Cardiovascular Risk in Asymptomatic Adults,” the ACCF/AHA also recommended ABI as a reasonable tool for cardiovascular risk assessment among patients at intermediate risk (17).
Table 1: What the Grades Mean and Suggestions for Practice
Table 2: Levels of Certainty Regarding Net Benefit
|Level of Certainty*||Description|
|High||The available evidence usually includes consistent results from well-designed, well-conducted studies in representative primary care populations. These studies assess the effects of the preventive service on health outcomes. This conclusion is therefore unlikely to be strongly affected by the results of future studies.|
|Moderate||The available evidence is sufficient to determine the effects of the preventive service on health outcomes, but confidence in the estimate is constrained by factors such as:
As more information becomes available, the magnitude or direction of the observed effect could change, and this change may be large enough to alter the conclusion.
|Low||The available evidence is insufficient to assess effects on health outcomes. Evidence is insufficient because of:
More information may allow an estimation of effects on health outcomes.
*The U.S. Preventive Services Task Force defines certainty as "likelihood that the USPSTF assessment of the net benefit of a preventive service is correct." The net benefit is defined as benefit minus harm of the preventive service as implemented in a general, primary care population. The USPSTF assigns a certainty level based on the nature of the overall evidence available to assess the net benefit of a preventive service.
1. Pande RL, Perlstein TS, Beckman JA, Creager MA. Secondary prevention and mortality in peripheral artery disease: National Health and Nutrition Examination Study, 1999 to 2004. Circulation. 2011;124(1):17-23.
2. Fowkes FG, Price JF, Stewart MC, Butcher I, Leng GC, Pell AC, et al; Aspirin for Asymptomatic Atherosclerosis Trialists. Aspirin for prevention of cardiovascular events in a general population screened for a low ankle brachial index: a randomized controlled trial. JAMA. 2010;303(9):841-8.
3. Cassar K. Peripheral arterial disease. Clin Evid (Online). 2011;2011. pii: 0211.
4. Joosten MM, Pai JK, Bertoia ML, Rimm EB, Spiegelman D, Mittleman MA, et al. Associations between conventional cardiovascular risk factors and risk of peripheral artery disease in men. JAMA. 2012;308(16):1660-7.
5. Lin S, Olson C, Johnson E, Senger C, Williams C, Whitlock E. Ankle Brachial Index for Peripheral Artery Disease Screening and Cardiovascular Disease Risk Prediction in Asymptomatic Adults: A Systematic Evidence Review for the U.S. Preventive Services Task Force. Evidence Synthesis No. 100. AHRQ Publication No. 12-05162-EF-1. Rockville, MD: Agency for Healthcare Research and Quality; 2013.
6. Hirsch AT, Haskal ZJ, Hertzer NR, Bakal CW, Creager MA, Halperin JL, et al. ACC/AHA 2005 practice guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic). Circulation. 2006;113(11):e463-654.
7. Mohler ER III, Treat-Jacobson D, Reilly MP, Cunningham KE, Miani M, Criqui MH, et al. Utility and barriers to performance of the ankle-brachial index in primary care practice. Vasc Med. 2004;9(4):253-60.
8. U.S. Preventive Services Task Force. Screening for Peripheral Arterial Disease: Recommendation Statement. AHRQ Publication No. 05-0583-A-EF. Rockville, MD: Agency for Healthcare Research and Quality; 2005.
9. Wikström J, Hansen T, Johansson L, Lind L, Ahlström H. Ankle brachial index <0.9 underestimates the prevalence of peripheral artery occlusive disease assessed with whole-body magnetic resonance angiography in the elderly. Acta Radiol. 2008;49(2):143-9.
10. Ankle Brachial Index Collaboration; Fowkes FG, Murray GD, Butcher I, Heald CL, Lee RJ, Chambless LE, et al. Ankle brachial index combined with Framingham Risk Score to predict cardiovascular events and mortality: a meta-analysis. JAMA. 2008;300(2):197-208.
11. Rodondi N, Marques-Vidal P, Butler J, Sutton-Tyrrell K, Cornuz J, Satterfield S, et al; Health, Aging, and Body Composition Study. Markers of atherosclerosis and inflammation for prediction of coronary heart disease in older adults. Am J Epidemiol. 2010;171(5):540-9.
12. Kavousi M, Elias-Smale S, Rutten JH, Leening MJ, Vliegenthart R, Verwoert GC, et al. Evaluation of newer risk markers for coronary heart disease risk classification: a cohort study. Ann Intern Med. 2012;156(6):438-44.
13. Yeboah J, McClelland RL, Polonsky TS, Burke GL, Sibley CT, O'Leary D, et al. Comparison of novel risk markers for improvement in cardiovascular risk assessment in intermediate-risk individuals. JAMA. 2012;308(8):788-95.
14. Lee AJ, Price JF, Russell MJ, Smith FB, van Wijk MC, Fowkes FG. Improved prediction of fatal myocardial infarction using the ankle brachial index in addition to conventional risk factors: the Edinburgh Artery Study. Circulation. 2004;110(19):3075-80.
15. McDermott MM, Reed G, Greenland P, Mazor KM, Pagoto S, Ockene JK, et al. Activating peripheral arterial disease patients to reduce cholesterol: a randomized trial. Am J Med. 2011;124(6):557-65.
16. Rooke TW, Hirsch AT, Misra S, Sidawy AN, Beckman JA, Findeiss LK, et al. 2011 ACCF/AHA focused update of the guideline for the management of patients with peripheral artery disease (updating the 2005 guideline): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2011;58(19):2020-45.
17. Greenland P, Alpert JS, Beller GA, Benjamin EJ, Budoff MJ, Fayad ZA, et al. 2010 ACCF/AHA guideline for assessment of cardiovascular risk in asymptomatic adults: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2010;56(25):e50-103.
AHRQ Publication No. 12-05162-EF-2
Current as of April 2013
U.S. Preventive Services Task Force. Screening for Peripheral Artery Disease and Cardiovascular Disease Risk Assessment With Ankle Brachial Index in Adults: Draft Recommendation Statement. AHRQ Publication No. 12-05162-EF-2. http://www.uspreventiveservicestaskforce.org/uspstf12/pad/paddraftrec.htm