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1.  Automated Ankle-Brachial Pressure Index Measurement by Clinical Staff for Peripheral Arterial Disease Diagnosis in Nondiabetic and Diabetic Patients 
Diabetes Care  2009;32(7):1231-1236.
OBJECTIVE
Peripheral arterial disease (PAD) is a prognostic marker in cardiovascular disease. The use of Doppler-measured ankle-brachial pressure index (Dop-ABI) for PAD diagnosis is limited because of time, required training, and costs. We assessed automated oscillometric measurement of the ankle-brachial pressure index (Osc-ABI) by nurses and clinical staff.
RESEARCH DESIGN AND METHODS
Clinical staff obtained Osc-ABI with an automated oscillometric device in 146 patients (83 with diabetes) at the time of Dop-ABI measurement and ultrasound evaluation.
RESULTS
Measurements were obtained in most legs (Dop-ABI 98%; Osc-ABI 95.5%). Dop- and Osc-ABI were significantly related in diabetic and nondiabetic patients with good agreement over a wide range of values. When Dop-ABI ≤0.90 was used as the gold standard for PAD, receiver operating characteristic curve analysis showed that PAD was accurately diagnosed with Osc-ABI in diabetic patients. When ultrasound was used to define PAD, Dop-ABI had better diagnostic performance than Osc-ABI in the whole population and in diabetic patients (P = 0.026). Both methods gave similar results in nondiabetic patients. The cutoff values for the highest sensitivity and specificity for PAD screening were between 1.0 and 1.1. Estimation of cost with the French medical care system fees showed a potential reduction by three of the screening procedures.
CONCLUSIONS
PAD screening could be improved by using Osc-ABI measured by clinical staff with the benefit of greater cost-effectiveness but at the risk of lower diagnostic performance in diabetic patients.
doi:10.2337/dc08-2230
PMCID: PMC2699730  PMID: 19366974
2.  Pocket Doppler and vascular laboratory equipment yield comparable results for ankle brachial index measurement 
Background
The ankle brachial index (ABI) is a well-established tool for screening and diagnosis of peripheral arterial disease (PAD). In this study we assessed the validity of ABI determination using a pocket Doppler device compared with automatic vascular laboratory measurement in patients suspected of PAD.
Methods
Consecutive patients with symptoms of PAD referred for ABI measurement between December 2006 and August 2007 were included. Resting ABI was determined with a pocket Doppler, followed by ABI measurement with automatic vascular laboratory equipment, performed by an experienced vascular technician. The leg with the lowest ABI was used for analysis.
Results
From 99 patients the mean resting ABI was 0.80 measured with the pocket Doppler and 0.85 measured with vascular laboratory equipment. A Bland-Altman plot demonstrated great correspondence between the two methods. The mean difference between the two methods was 0.05 (P < .001). Multivariate linear regression analysis showed no dependency of the difference on either the average measured ABI or affected or unaffected leg.
Conclusion
Since the small, albeit statistically significant, difference between the two methods is not clinically relevant, our study demonstrates that ABI measurements with pocket Doppler and vascular laboratory equipment yield comparable results and can replace each other. Results support the use of the pocket Doppler for screening of PAD, allowing initiation of cardiovascular risk factor management in primary care, provided that the equipment operator is experienced.
doi:10.1186/1471-2261-8-26
PMCID: PMC2567287  PMID: 18840278
3.  Oscillometric measurement of the ankle-brachial index 
INTRODUCTION
Peripheral arterial disease is a coronary risk equivalent; a low ankle-brachial index (ABI) is indicative of systemic vascular disease, and should place a patient in the high-risk category. Few physicians measure ABI because it is technically challenging and time consuming. Oscillometric blood pressure monitors are readily available and easy to use. The use of a simple method of documenting ABI was assessed and compared with the conventional method.
METHODS
The oscillometric ABI (OABI) was measured for normal volunteers, patients attending a cardiovascular risk clinic (Cardiovascular Risk Factor Reduction Unit [CRFRU] at the University of Saskatchewan, Saskatoon) and patients referred to a vascular laboratory (vasc lab). The latter group had Doppler ABI (DABI) measurements and served to validate OABI. An Omron HEM 711C oscillometric system (Omron Canada Inc) with appropriate cuff size for arm and leg circumference was used.
RESULTS
The mean ± SEM OABI was 1.13±0.08 in normal volunteers (n=26), 1.10±0.10 in CRFRU patients (n=11, P not significant) and 1.03±0.14 in vasc lab patients (n=57, P<0.05 compared with normal volunteers). No difference was found between sexes, and there was no correlation with age. In the vasc lab group, the correlation with DABI was 0.71 (P<0.05). The sensitivity of OABI to detect DABI of less than 0.9 was 0.71, and the specificity was 0.89. OABI was found to be less sensitive at detecting low values in patients with nonpalpable pulses on physical examination.
CONCLUSION
The OABI is feasible and operator-independent, but does not detect low ABI efficiently. If OABI is abnormal, low DABI is likely. The OABI is less likely to detect disease in patients with nonpalpable peripheral pulses. Such patients are better referred directly to a vascular laboratory for DABI testing.
PMCID: PMC2631249  PMID: 18209769
Ankle-brachial index; Atherosclerosis; Diagnosis; Peripheral vascular disease; Risk factors
4.  Utility of Toe-brachial Index for Diagnosis of Peripheral Artery Disease 
Archives of Plastic Surgery  2012;39(3):227-231.
Background
The ankle brachial pressure index (ABI) is a simple, useful method for diagnosing peripheral artery disease (PAD). Although the ABI is an objective diagnostic method, it has limited reliability in certain scenarios. The aim of the present study was to determine the accuracy and reliability of the toe brachial index (TBI) as a diagnostic tool for detecting stenosis in PAD, associated with normal or low ABI values.
Methods
ABI and TBI values were measured in 15 patients with diabetic gangrene who were suspected of having lower extremity arterial insufficiency. The ABI and TBI values were measured using a device that allowed the simultaneous measurement of systolic blood pressure in the upper and lower extremities. In addition, the ABI and TBI values were compared pre- and post-angiography.
Results
Patients with an ABI of 0.9-1.3 showed almost no difference between the 2 measurements. The patients with TBI >0.6 had no arterial insufficiency. The patients with TBI <0.6 required vascular intervention with ballooning. After the angiography, the gangrenous wounds decreased in size more rapidly than they did prior to the intervention.
Conclusions
Our findings suggest that TBI is the method of choice for evaluating lower limb perfusion disorders. This result requires further studies of TBI in a larger number of patients. Future long-term studies should therefore evaluate the utility of TBI as a means of screening for PAD and the present findings should be regarded as preliminary outcomes.
doi:10.5999/aps.2012.39.3.227
PMCID: PMC3385338  PMID: 22783531
Toe brachial index; Ankle brachial index; Peripheral arterial disease
5.  A Comparison between Brachial and Echocardiographic Systolic Time Intervals 
PLoS ONE  2013;8(2):e55840.
Systolic time interval (STI) is an established noninvasive technique for the assessment of cardiac function. Brachial STIs can be automatically determined by an ankle-brachial index (ABI)-form device. The aims of this study are to evaluate whether the STIs measured from ABI-form device can represent those measured from echocardiography and to compare the diagnostic values of brachial and echocardiographic STIs in the prediction of left ventricular ejection fraction (LVEF) <50%. A total of 849 patients were included in the study. Brachial pre-ejection period (bPEP) and brachial ejection time (bET) were measured using an ABI-form device and pre-ejection period (PEP) and ejection time (ET) were measured from echocardiography. Agreement was assessed by correlation coefficient and Bland-Altman plot. Brachial STIs had a significant correlation with echocardiographic STIs (r = 0.644, P<0.001 for bPEP and PEP; r  = 0.850, P<0.001 for bET and ET; r = 0.708, P<0.001 for bPEP/bET and PEP/ET). The disagreement between brachial and echocardiographic STIs (brachial STIs minus echocardiographic STIs) was 28.55 ms for bPEP and PEP, -4.15 ms for bET and ET and -0.11 for bPEP/bET and PEP/ET. The areas under the curve for bPEP/bET and PEP/ET in the prediction of LVEF <50% were 0.771 and 0.765, respectively. Brachial STIs were good alternatives to STIs obtained from echocardiography and also helpful in prediction of LVEF <50%. Brachial STIs automatically obtained from an ABI-form device may be helpful for evaluation of left ventricular systolic dysfunction.
doi:10.1371/journal.pone.0055840
PMCID: PMC3567004  PMID: 23409059
6.  The reliability of the ankle-brachial index in the Atherosclerosis Risk in Communities (ARIC) study and the NHLBI Family Heart Study (FHS) 
Background
A low ankle-brachial index (ABI) is associated with increased risk of coronary heart disease, stroke, and death. Regression model parameter estimates may be biased due to measurement error when the ABI is included as a predictor in regression models, but may be corrected if the reliability coefficient, R, is known. The R for the ABI computed from DINAMAP™ readings of the ankle and brachial SBP is not known.
Methods
A total of 119 participants in both the Atherosclerosis Risk in Communities (ARIC) study and the NHLBI Family Heart Study (FHS) had repeat ABIs taken within 1 year, using a common protocol, automated oscillometric blood pressure measurement devices, and technician pool.
Results
The estimated reliability coefficient for the ankle systolic blood pressure (SBP) was 0.68 (95% CI: 0.57, 0.77) and for the brachial SBP was 0.74 (95% CI: 0.62, 0.83). The reliability for the ABI based on single ankle and arm SBPs was 0.61 (95% CI: 0.50, 0.70) and the reliability of the ABI computed as the ratio of the average of two ankle SBPs to two arm SBPs was estimated from simulated data as 0.70.
Conclusion
These reliability estimates may be used to obtain unbiased parameter estimates if the ABI is included in regression models. Our results suggest the need for repeated measures of the ABI in clinical practice, preferably within visits and also over time, before diagnosing peripheral artery disease and before making therapeutic decisions.
doi:10.1186/1471-2261-6-7
PMCID: PMC1435775  PMID: 16504033
7.  Ankle-Brachial Index: A Simple Way to Predict Mortality among Patients on Hemodialysis - A Prospective Study 
PLoS ONE  2012;7(7):e42290.
Background
Ankle-brachial index (ABI) can access peripheral artery disease and predict mortality in prevalent patients on hemodialysis. However, ABI has not yet been tested in incident patients, who present significant mortality. Typically, ABI is measured by Doppler, which is not always available, limiting its use in most patients. We therefore hypothesized that ABI, evaluated by a simplified method, can predict mortality in an incident hemodialysis population.
Methodology/Principal Findings
We studied 119 patients with ESRD who had started hemodialysis three times weekly. ABI was calculated by using two oscillometric blood pressure devices simultaneously. Patients were followed until death or the end of the study. ABI was categorized in two groups normal (0.9–1.3) or abnormal (<0.9 and >1.3). There were 33 deaths during a median follow-up of 12 months (from 3 to 24 months). Age (1 year) (hazard of ratio, 1.026; p = 0.014) and ABI abnormal (hazard ratio, 3.664; p = 0.001) were independently related to mortality in a multiple regression analysis.
Conclusions
An easy and inexpensive technique to measure ABI was tested and showed to be significant in predicting mortality. Both low and high ABI were associated to mortality in incident patients on hemodialysis. This technique allows nephrologists to identify high-risk patients and gives the opportunity of early intervention that could alter the natural progression of this population.
doi:10.1371/journal.pone.0042290
PMCID: PMC3408472  PMID: 22860108
8.  Ankle brachial index measurement in primary care: are we doing it right? 
Background
The reference standard for diagnosing peripheral arterial disease in primary care is the ankle brachial index (ABI). Various methods to measure ankle and brachial blood pressures and to calculate the index are described.
Aim
To compare the ABI measurements performed in primary care with those performed in the vascular laboratory. Furthermore, an inventory was made of methods used to determine the ABI in primary care.
Design of study
Cross-sectional study.
Setting
Primary care practice and outpatient clinic.
Method
Consecutive patients suspected of peripheral arterial disease based on ABI assessment in primary care practices were included. The ABI measurements were repeated in the vascular laboratory. Referring GPs were interviewed about method of measurement and calculation of the index. From each patient the leg with the lower ABI was used for analysis.
Results
Ninety-nine patients of 45 primary care practices with a mean ABI of 0.80 (standard deviation [SD] = 0.27) were included. The mean ABI as measured in the vascular laboratory was 0.82 (SD = 0.26). A Bland–Altman plot demonstrated great variability between ABI measurements in primary care practice and the vascular laboratory. Both method of blood pressure measurements and method of calculating the ABI differed greatly between primary care practices.
Conclusion
This study demonstrates that the ABI is often not correctly determined in primary care practice. This phenomenon seems to be due to inaccurate methods for both blood pressure measurements and calculation of the index. A guideline for determining the ABI with a hand-held Doppler, and a training programme seem necessary.
doi:10.3399/bjgp09X420932
PMCID: PMC2688044  PMID: 19520025
diagnosis; Doppler effect; intermittent claudication; peripheral vascular diseases; ultrasonography
9.  The Relevance of Different Methods of Calculating the Ankle-Brachial Index 
American Journal of Epidemiology  2009;171(3):368-376.
The authors aimed to determine differences in the prevalence of peripheral arterial disease (PAD) and its associations with cardiovascular disease (CVD) risk factors, using different methods of calculating the ankle-brachial index (ABI). Using measurements taken in the bilateral brachial, dorsalis pedis, and posterior tibial arteries, the authors calculated ABI in 3 ways: 1) with the lowest ankle pressure (dorsalis pedis artery or posterior tibial artery) (“ABI-LO”), 2) with the highest ankle pressure (“ABI-HI”), and 3) with the mean of the ankle pressures (“ABI-MN”). For all 3 methods, the index ABI was the lower of the ABIs calculated from the left and right legs. PAD was defined as an ABI less than 0.90. Among 6,590 subjects from a multiethnic cohort (baseline examination: 2000–2002), in comparison with ABI-HI, the relative prevalence of PAD was 3.95 times higher in women and 2.74 times higher in men when ABI-LO was used. The relative magnitudes of the associations were largest between PAD and both subclinical atherosclerosis and CVD risk factors when ABI-HI was used, except when risk estimates for PAD were less than 1.0, where the largest relative magnitudes of association were found using ABI-LO. PAD prevalence and its associations with CVD risk factors and subclinical atherosclerosis measures depend on the ankle pressure used to compute the ABI.
doi:10.1093/aje/kwp382
PMCID: PMC2842203  PMID: 20042436
ankle brachial index; cardiovascular diseases; continental population groups; ethnic groups; peripheral vascular diseases
10.  Comparison between oscillometric- and Doppler-ABI in elderly individuals 
Peripheral arterial disease (PAD) generally remains under-recognized, mainly due to the specialized technical skills required to detect the low values of the ankle-brachial index (ABI). As a simpler and faster alternative to the standard method using continuous-wave Doppler ultrasound, we evaluated automated oscillometric ABI measurement by VP-2000 with an elderly cohort of 113 subjects (age range, 61 to 88 years). The standard deviation in ABIs measured by the Doppler method was statistically greater than that measured by the oscillometric method for each of the two legs (P < 0.001). Correlations in ABIs between the two methods were 0.46 for the left leg and 0.61 for the right leg; this result appears to have been caused by interobserver variation in the Doppler ABI measurements. While the trend showing greater differences between average oscillometric- and Doppler-ABIs was significant at the lower ABI ranges, there was little indication of differences in measurements having an average ABI > 1.1. The difference between the methods was suggestively larger in subjects who were smokers than in non-smokers (P = 0.09), but the difference was not affected by other potential atherosclerotic risk factors, including age at examination (P > 0.50). A larger difference at lower ABIs led to better PAD detection by the Doppler method compared to the oscillometric method (sensitivity = 50%, specificity = 100%), although the overall agreement was not small (Cohen’s Kappa = 0.65). Our findings indicate that oscillometric devices can provide more accurate estimation of the prevalence of PAD in elderly individuals than the conventional Doppler method.
doi:10.2147/VHRM.S39785
PMCID: PMC3593766  PMID: 23493262
ankle-brachial index; oscillometry; Doppler; peripheral arterial disease
11.  Current utility of the ankle-brachial index (ABI) in general practice: implications for its use in cardiovascular disease screening 
BMC Family Practice  2014;15:69.
Background
Peripheral arterial disease (PAD) is a marker of systemic atherosclerosis and associated with a three to six fold increased risk of death from cardiovascular causes. Furthermore, it is typically asymptomatic and under-diagnosed; this has resulted in escalating calls for the instigation of Primary Care PAD screening via Ankle Brachial Index (ABI) measurement. However, there is limited evidence regarding the feasibility of this and if the requisite core skills and knowledge for such a task already exist within primary care. This study aimed to determine the current utility of ABI measurement in general practices across Wales, with consideration of the implications for its use as a cardiovascular risk screening tool.
Method
A self-reporting questionnaire was distributed to all 478 General Practices within Wales, sent via their responsible Health Boards.
Results
The survey response rate was 20%. ABI measurement is primarily performed by nurses (93%) for the purpose of wound management (90%). It is infrequently (73% < 4 times per month) and often incorrectly used (42% out of compliance with current ABI guidance). Only 52% of general practitioners and 16% of nurses reported that patients with an ABI of ≤ 0.9 require aggressive cardiovascular disease risk factor modification (as recommended by current national and international guidelines).
Conclusion
ABI measurement is an under-utilised and often incorrectly performed procedure in the surveyed general practices. Prior to its potential adoption as a formalised screening tool for cardiovascular disease, there is a need for a robust training programme with standardised methodology in order to optimise accuracy and consistency of results. The significance of a diagnosis of PAD, in terms of associated increased cardiovascular risk and the necessary risk factor modification, needs to be highlighted.
doi:10.1186/1471-2296-15-69
PMCID: PMC4021160  PMID: 24742018
Peripheral arterial disease; Doppler ultrasound; Atherosclerosis; Secondary prevention
12.  Perceptions of the ankle brachial index amongst podiatrists registered in Western Australia 
Background
The ankle brachial index (ABI) is an objective diagnostic tool that is widely used for the diagnosis of peripheral arterial disease. Despite its usefulness, it is evident within the literature that many practitioners forgo using this screening tool due to limiting factors such as time. There is also no recommended technique for ABI measurement. The purpose of this study is to investigate the perceptions of the use of ABI clinically among Western Australian podiatrists.
Methods
This study was a cross sectional survey which evaluated the perceptions of the ABI amongst registered podiatrists in Western Australia. The study sample was obtained from the register of podiatrists listed with the Podiatrists Registration Board of Western Australia. Podiatrists were contacted by telephone and invited to participate in a telephone questionnaire. Chi-square tests were performed to determine if there was a statistically significant relationship between use of the ABI and podiatrists’ profile which included: sector of employment; geographical location; and length of time in practice.
Results
There is a statistically significant relationship (p=0.004) between podiatrists’ profile and the use of ABI, with higher usage in the tertiary hospital setting than in private practice. Length of time spent in practice had no significant impact on ABI usage (p=0.098). Time constraints and lack of equipment were key limiting factors to performing the ABI, and no preferred technique was indicated.
Conclusion
Western Australian podiatrists agree that the ABI is a useful tool for lower limb vascular assessment, however, various factors influence uptake in the clinical setting. This study suggests that a podiatrists’ profile has a significant influence on the use of the ABI, which may be attributed to different patient types across the various settings. The influence of time spent in practice on ABI usage may be attributed to differences in clinical training and awareness of lower limb pathology over time. The authors recommend publication of ‘best practice’ guidelines to ABI performance, as well as further education and financial rebates from health organizations to facilitate increased utility of the ABI based on the findings of this study.
doi:10.1186/1757-1146-5-19
PMCID: PMC3520691  PMID: 22846188
13.  Ankle-Brachial index by oscillometry: A very useful method to assess peripheral arterial disease in diabetes 
Background:
Peripheral Arterial Disease (PAD) remains the least recognized form of atherosclerosis. The Ankle-Brachial Index (ABI) has emerged as one of the potent markers of diffuse atherosclerosis, cardiovascular (CV) risk, and overall survival in general public, especially in diabetics. The important reason for the lack of early diagnosis is the non-availability of a test that is easy to perform and less expensive, with no training required.
Objectives:
To evaluate the osillometric method of performing ABI with regard to its usefulness in detecting PAD cases and to correlate the signs and symptoms with ABI.
Materials and Methods:
Two hundred diabetics of varying duration attending the clinic for a period of eight months, from August 2006 to April 2007, were evaluated for signs, symptoms, and risk factors. ABI was performed using the oscillometric method. The positives were confirmed by Doppler evaluation. An equal number of age- and sex-matched controls, which were ABI negative, were also assessed by Doppler. Sensitivity and Specificity were determined.
Results:
There were 120 males and 80 females. Twelve males (10%) and six females (7.5%) were ABI positive. On Doppler, eleven males (91.5%) and three females (50%) were true positives. There were six false negatives from the controls (three each). The Sensitivity was 70% and Specificity was 75%. Symptoms and signs correlated well with ABI positives. Hypertension was the most important risk factor.
Conclusions:
In spite of the limitations, the oscillometric method of performing ABI is a simple procedure, easy to perform, does not require training and can be performed as an outpatient procedure not only by doctors, but also by the paramedical staff to detect more PAD cases.
doi:10.4103/0973-3930.62600
PMCID: PMC2878698  PMID: 20535314
Ankle-Brachial Index; oscillometric method; PAD; risk factors; sensitivity; specificity
14.  Measurement of the ankle brachial index with a non-mercury sphygmomanometer in diabetic patients: a concordance study 
Background
The removal of mercury sphygmomanometers from health centers requires the validation of other instruments to measure blood pressure in the limbs to calculate the ankle-brachial index (ABI).
Methods
Descriptive cross-sectional study of agreement between two measurement methods in type 2 diabetes patients from three urban primary healthcare centres in the Barcelonès Nord i Maresme area (Catalonia, Spain).
ABI was determined with Doppler and mercury sphygmomanometer and Doppler and the “hybrid” sphygmomanometer OMRON HEM-907 model. Agreement was evaluated using the weighted kappa index. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated using the mercury sphygmomanometer as the gold standard.
Results
211 patients were included, from these, 421 limbs were available for study. The mean age of the participants was 67 years (SD = 10), 51.7% were women.
The index of agreement between ABI measured with a mercury sphygmomanometer and with the OMRON HEM-907 blood pressure monitor was good (weighted kappa index = 0.68; CI 95%: [0.55–0.79]) and improved when the ABI cut-off value was set at ≤0.70 (weighted kappa index = 0.92; CI 95%: [0.81–1.00]). Sensitivity and specificity were 77.5% and 98.2%, respectively. PPV was 83.8% and NPV was 97.3%. With the ABI cut-off value ≤0.70, sensitivity and specificity increased to 85.7% and 100%, respectively, PPV to 100% and NPV to 99.4%.
Conclusion
The combination of a Doppler device with the hybrid sphygmomanometer is a simple and reliable method to measure ABI showing that hybrid sphygmomanometer is a good alternative to the use of mercury sphygmomanometers.
doi:10.1186/1471-2261-13-15
PMCID: PMC3614496  PMID: 23497339
Ankle brachial blood pressure index; Peripheral arterial disease; Blood pressure; Type 2 diabetes mellitus; Doppler; Sensitivity and specificity
15.  The validity of ankle-brachial index for the differential diagnosis of peripheral arterial disease and lumbar spinal stenosis in patients with atypical claudication 
European Spine Journal  2011;21(6):1165-1170.
Purpose
Claudication is a typical symptom of peripheral arterial disease (PAD) and lumbar spinal stenosis (LSS). Differential diagnosis of PAD and LSS is often difficult due to the subjective natures of symptoms and atypical signs. The authors aimed to determine the usefulness of ankle-brachial index (ABI) measurement for the differential diagnosis of PAD and LSS when the etiology of claudication is uncertain.
Methods
Forty-two consecutive patients who had been referred by spine surgeons to a lower extremity vascular surgeon for atypical claudication were retrospectively analyzed. Atypical claudication was defined as claudication not caused by PAD, as determined by clinical manifestations, or by LSS, as determined by MR imaging. A final diagnosis of PAD was established by CT angiography (CTA) and of LSS by excluding PAD. Diagnostic validity of ABI for PAD in atypical presentation was assessed.
Results
Sixty-two legs of 42 atypical claudication patients were analyzed. Mean patient age was 65.8 ± 8.2 years (38–85) and 29 (69.0%) had diabetes mellitus. Mean ABI was 0.73 ± 0.14 (0.53–0.94) in the PAD group and 0.92 ± 0.18 (0.52–1.10) in the LSS group (P < 0.001). Of the 33 legs with a low ABI (ABI < 0.9), 29 legs were diagnosed as true positives for PAD by CTA and 4 were false positives, and of the 29 legs with a high ABI, 5 were false negatives and 24 were true negatives. The sensitivity and specificity of ABI for the diagnosis of PAD in patients with atypical claudication were 85.3 and 85.7%, respectively, and its positive and negative predictive values were 87.9 and 82.8%.
Conclusions
ABI is a recommended screening test for the differential diagnosis of lower leg claudication when clinical symptoms are atypical.
doi:10.1007/s00586-011-2072-3
PMCID: PMC3366123  PMID: 22105308
Claudication; Peripheral arterial disease; Lumbar spinal stenosis; Ankle-brachial index; Validity
16.  Brachial-ankle pulse wave velocity is associated with walking distance in patients referred for peripheral arterial disease evaluation 
Atherosclerosis  2009;206(1):173-178.
Objective
Impaired functional capacity predicts morbidity and increased mortality in patients with PAD. We hypothesized that brachial-ankle pulse wave velocity (baPWV), a measure of arterial stiffness, is associated with functional capacity in patients undergoing noninvasive evaluation for peripheral arterial disease (PAD).
Methods
We studied 114 patients (age 68 ± 10 years) referred to Mayo Clinic’s noninvasive vascular laboratory. Functional capacity was estimated in terms of distance walked in 5 min on a treadmill at a speed of 1.0–2.0 mph. Ankle-brachial index (ABI) was obtained with Doppler method before and 1 min after exercise. baPWV was estimated noninvasively using an oscillometric device. The association of baPWV with walking distance was assessed using accelerated failure time and Cox proportional-hazards models.
Results
The mean baPWV was higher in patients who were unable to complete the walk test compared to those who successfully completed the test (P = 0.008). Higher baPWV was associated with a lower walking distance after adjustment for heart rate, mean arterial pressure, and cardiovascular risk factors (P = 0.017) and after additional adjustment for pulse pressure (P = 0.034) and ABI (P = 0.030). Higher baPWV was associated with failure to complete the treadmill walk test, after adjustment for heart rate, mean arterial pressure, and cardiovascular risk factors (P = 0.025) and after additional adjustment for pulse pressure (P = 0.041) and ABI (P = 0.039).
Conclusion
Increased baPWV, a measure of arterial stiffness, is associated with impaired functional capacity in patients undergoing evaluation for PAD.
doi:10.1016/j.atherosclerosis.2009.02.003
PMCID: PMC2956123  PMID: 19278681
Arterial stiffness; Brachial-ankle pulse wave velocity; Functional capacity; Peripheral arterial disease
17.  To screen or not to screen for peripheral arterial disease in subjects aged 80 and over in primary health care: a cross-sectional analysis from the BELFRAIL study 
BMC Family Practice  2011;12:39.
Background
Peripheral arterial disease (PAD) is common in older people. An ankle-brachial index (ABI) < 0.9 can be used as an indicator of PAD. Patients with low ABI have increased mortality and a higher risk of serious cardiovascular morbidity. However, because 80% of the patients are asymptomatic, PAD remains unrecognised in a large group of patients. The aims of this study were 1) to examine the prevalence of reduced ABI in subjects aged 80 and over, 2) to determine the diagnostic accuracy of the medical history and clinical examination for reduced ABI and 3) to investigate the difference in functioning and physical activity between patients with and without reduced ABI.
Methods
A cross-sectional study embedded within the BELFRAIL study. A general practitioner (GP) centre, located in Hoeilaart, Belgium, recruited 239 patients aged 80 or older. Only three criteria for exclusion were used: urgent medical need, palliative situation and known serious dementia. The GP recorded the medical history and performed a clinical examination. The clinical research assistant performed an extensive examination including Mini-Mental State Examination (MMSE), Geriatric Depression Scale (GDS-15), Activities of Daily Living (ADL), Tinetti test and the LASA Physical Activity Questionnaire (LAPAQ). ABI was measured using an automatic oscillometric appliance.
Results
In 40% of patients, a reduced ABI was found. Cardiovascular risk factors were unable to identify patients with low ABI. A negative correlation was found between the number of cardiovascular morbidities and ABI. Cardiovascular morbidity had a sensitivity of 65.7% (95% CI 53.4-76.7) and a specificity of 48.6% (95% CI 38.7-58.5). Palpation of the peripheral arteries showed the highest negative predictive value (77.7% (95% CI 71.8-82.9)). The LAPAQ score was significantly lower in the group with reduced ABI.
Conclusion
The prevalence of PAD is very high in patients aged 80 and over in general practice. The clinical examination, cardiovascular risk factors and the presence of cardiovascular morbidity were not able to identify patients with a low ABI. A screening strategy for PAD by determining ABI could be considered if effective interventions for those aged 80 and over with a low ABI become available through future research.
doi:10.1186/1471-2296-12-39
PMCID: PMC3121584  PMID: 21605447
18.  Profound influence of different methods for determination of the ankle brachial index on the prevalence estimate of peripheral arterial disease 
BMC Public Health  2007;7:147.
Background
The ankle brachial index (ABI) is an efficient tool for objectively documenting the presence of lower extremity peripheral arterial disease (PAD). However, different methods exist for ABI calculation, which might result in varying PAD prevalence estimates. To address this question, we compared five different methods of ABI calculation using Doppler ultrasound in 6,880 consecutive, unselected primary care patients ≥65 years in the observational getABI study.
Methods
In all calculations, the average systolic pressure of the right and left brachial artery was used as the denominator (however, in case of discrepancies of ≥10 mmHg, the higher reading was used). As nominators, the following pressures were used: the highest arterial ankle pressure of each leg (method #1), the lowest pressure (#2), only the systolic pressure of the tibial posterior artery (#3), only the systolic pressure of the tibial anterior artery (#4), and the systolic pressure of the tibial posterior artery after exercise (#5). An ABI < 0.9 was regarded as evidence of PAD.
Results
The estimated prevalence of PAD was lowest using method #1 (18.0%) and highest using method #2 (34.5%), while the differences in methods #3–#5 were less pronounced. Method #1 resulted in the most accurate estimation of PAD prevalence in the general population. Using the different approaches, the odds ratio for the association of PAD and cardiovascular (CV) events varied between 1.7 and 2.2.
Conclusion
The data demonstrate that different methods for ABI determination clearly affect the estimation of PAD prevalence, but not substantially the strength of the associations between PAD and CV events. Nonetheless, to achieve improved comparability among different studies, one mode of calculation should be universally applied, preferentially method #1.
doi:10.1186/1471-2458-7-147
PMCID: PMC1950873  PMID: 18293542
19.  The Relation Between Ankle-Brachial Index (ABI) and Coronary Artery Disease Severity and Risk Factors: An Angiographic Study 
ARYA Atherosclerosis  2011;7(2):68-73.
BACKGROUND
The current study aims to determine the relation between ankle–brachial index (ABI) and angiographic findings and major cardiovascular risk factors in patients with suspected coronary artery diseases (CAD) in Isfahan.
METHODS
In this cross-sectional descriptive-analytic research, patients with suspected CAD were studied. Characteristics of studied subjects including demographics, familial history, past medical history and atherosclerotic risk factors such as diabetes mellitus, hypertension, hyperlipidemia and smoking were obtained using a standard questionnaire. ABI was measured in all studied patients. ABI≤0.9 (ABI+) was considered as peripheral vessel disease and ABI>0.9 (ABI-) was considered as normal. Then, all studied patients underwent coronary artery angiography. The results of the questionnaire and angiographic findings were compared in ABI+ and ABI- groups. Data were analyzed by SPSS 15 using ANOVA, t-test, Spearman's rank correlation coefficient, and discriminant analysis.
RESULTS
In this study, 125 patients were investigated. ABI≤0.9 was seen in 25 patients (20%). The prevalence of ABI+ among men and women was 25.9% and 7.5%, respectively (P=0.01). The prevalence of atherosclerotic risk factors was significantly higher in ABI+ patients than in ABI- ones (P<0.05). ABI+ patients had more significant stenosis than ABI- ones. The mean of occlusion was significantly higher in ABI+ patients with left main artery (LMA), right coronary artery (RCA), left anterior descending artery (LAD), diagonal artery 1 (D1) and left circumflex artery (LCX) involvements (P<0.05).
CONCLUSION
The findings of this research indicated that ABI could be a useful method in assessing both the atherosclerotic risk factors and the degree of coronary involvements in suspected patients. However, in order to make more accurate decisions for using this method in diagnosing and preventing CAD, we should plan further studies in large sample sizes of general population.
PMCID: PMC3347847  PMID: 22577449
Ankle–Brachial Index; Angiography; Atherosclerotic Risk Factors.
20.  Association of Interarm Systolic Blood Pressure Difference with Atherosclerosis and Left Ventricular Hypertrophy 
PLoS ONE  2012;7(8):e41173.
An interarm systolic blood pressure (SBP) difference of 10 mmHg or more have been associated with peripheral artery disease and adverse cardiovascular outcomes. We investigated whether an association exists between this difference and ankle-brachial index (ABI), brachial-ankle pulse wave velocity (baPWV), and echocardiographic parameters. A total of 1120 patients were included in the study. The bilateral arm blood pressures were measured simultaneously by an ABI-form device. The values of ABI and baPWV were also obtained from the same device. Clinical data, ABI<0.9, baPWV, echocariographic parameters, and an interarm SBP difference ≥10 mmHg were compared and analyzed. We performed two multivariate forward analyses for determining the factors associated with an interarm SBP difference ≥10 mmHg [model 1: significant variables in univariate analysis except left ventricular mass index (LVMI); model 2: significant variables in univariate analysis except ABI<0.9 and baPWV]. The ABI<0.9 and high baPWV in model 1 and high LVMI in model 2 were independently associated with an interarm SBP difference ≥10 mmHg. Female, hypertension, and high body mass index were also associated with an interarm SBP difference ≥10 mmHg. Our study demonstrated that ABI<0.9, high baPWV, and high LVMI were independently associated with an interarm SBP difference of 10 mmHg or more. Detection of an interarm SBP difference may provide a simple method of detecting patients at increased risk of atherosclerosis and left ventricular hypertrophy.
doi:10.1371/journal.pone.0041173
PMCID: PMC3426512  PMID: 22927905
21.  Endothelial function in a cardiovascular risk population with borderline ankle–brachial index 
Introduction:
The diagnosis of peripheral arterial disease (PAD) can be made by measuring the ankle–brachial index (ABI). Traditionally ABI values > 1.00–1.40 have been considered normal and ABI ≤ 0.90 defines PAD. Recent studies, however, have shown that individuals with ABI values between 0.90–1.00 are also at risk of cardiovascular events. We studied this cardiovascular risk population subgroup in order to determine their endothelial function using peripheral arterial tonometry (PAT).
Methods:
We selected 66 individuals with cardiovascular risk and borderline ABI. They all had hypertension, newly diagnosed glucose disorder, metabolic syndrome, obesity, or a ten year risk of cardiovascular disease death of 5% or more according to the Systematic Coronary Risk Evaluation System (SCORE). Subjects with previously diagnosed diabetes or cardiovascular disease were excluded. Endothelial function was assessed by measuring the reactive hyperemia index (RHI) from fingertips using an Endo-PAT device.
Results:
The mean ABI was 0.95 and mean RHI 2.11. Endothelial dysfunction, defined as RHI < 1.67, was detected in 15/66 (23%) of the subjects. There were no statistically significant differences in RHI values between subjects with different cardiovascular risk factors. The only exception was that subjects with impaired fasting glucose (IFG) had slightly lower RHI values (mean RHI 1.91) than subjects without IFG (mean RHI 2.24) (P = 0.02).
Conclusions:
In a cardiovascular risk population with borderline ABI nearly every fourth subject had endothelial dysfunction, indicating an elevated risk of cardiovascular events. This might point out a subgroup of individuals in need of more aggressive treatment for their risk factors.
doi:10.2147/VHRM.S17249
PMCID: PMC3049545  PMID: 21415923
peripheral arterial disease; ankle–brachial index; cardiovascular risk; endothelial dysfunction
22.  Cost-Effectiveness of New Cardiac and Vascular Rehabilitation Strategies for Patients with Coronary Artery Disease 
PLoS ONE  2008;3(12):e3883.
Objective
Peripheral arterial disease (PAD) often hinders the cardiac rehabilitation program. The aim of this study was evaluating the relative cost-effectiveness of new rehabilitation strategies which include the diagnosis and treatment of PAD in patients with coronary artery disease (CAD) undergoing cardiac rehabilitation.
Data Sources
Best-available evidence was retrieved from literature and combined with primary data from 231 patients.
Methods
We developed a Markov decision model to compare the following treatment strategies: 1. cardiac rehabilitation only; 2. ankle-brachial index (ABI) if cardiac rehabilitation fails followed by diagnostic work-up and revascularization for PAD if needed; 3. ABI prior to cardiac rehabilitation followed by diagnostic work-up and revascularization for PAD if needed. Quality-adjusted-life years (QALYs), life-time costs (US $), incremental cost-effectiveness ratios (ICER), and gain in net health benefits (NHB) in QALY equivalents were calculated. A threshold willingness-to-pay of $75 000 was used.
Results
ABI if cardiac rehabilitation fails was the most favorable strategy with an ICER of $44 251 per QALY gained and an incremental NHB compared to cardiac rehabilitation only of 0.03 QALYs (95% CI: −0.17, 0.29) at a threshold willingness-to-pay of $75 000/QALY. After sensitivity analysis, a combined cardiac and vascular rehabilitation program increased the success rate and would dominate the other two strategies with total lifetime costs of $30 246 a quality-adjusted life expectancy of 3.84 years, and an incremental NHB of 0.06 QALYs (95%CI:−0.24, 0.46) compared to current practice. The results were robust for other different input parameters.
Conclusion
ABI measurement if cardiac rehabilitation fails followed by a diagnostic work-up and revascularization for PAD if needed are potentially cost-effective compared to cardiac rehabilitation only.
doi:10.1371/journal.pone.0003883
PMCID: PMC2587698  PMID: 19065259
23.  Exercise-Ankle Brachial Pressure Index with One-Minute Treadmill Walking in Patients on Maintenance Hemodialysis 
Annals of Vascular Diseases  2012;6(1):52-56.
Background: The ankle-brachial pressure index (ABI) is widely used as a standard screening method for arterial occlusive lesion above the knee. However, the sensitivity of ABI is low in hemodialysis (HD) patients. Exercise stress (Ex-ABI) may reduce the false negative results.
Patients and Methods: After measuring resting ABI and toe-brachial pressure index (TBI), ankle pressure and ABI immediately after walking (Post-AP, Post-ABI) were measured using one-minute treadmill walking in 52 lower limbs of 26 HD patients. The definition of peripheral arterial occlusive disease (PAD) required an ABI value of less than 0.90, TBI value of less than 0.60, and decrease of more than 15% of the Post-ABI value and 20 mmHg of Post-AP in Ex-ABI. Computed tomographic angiography (CTA) was performed in 32 lower limbs of 16 HD patients. PAD is defined as presence of stenosis of more than 75% in the case of lesions from an iliac artery to knee on CTA.
Results: The accuracy of Ex-ABI (Sensitivity, 85.7%; Specificity, 77.7%) was higher than those of ABI (Sensitivity, 42.9%; Specificity, 83.3%) or TBI (Sensitivity, 78.6%; Specificity, 61.1%).
Conclusion: Ex-ABI with one-minute treadmill walking is the most useful tool for the screening of arterial occlusive lesions above the knee in maintenance HD patients.
doi:10.3400/avd.oa.12.00070
PMCID: PMC3635000  PMID: 23641284
peripheral arterial disease; exercise; diagnosis; screening; hemodialysis
24.  Lower Extremity Nerve Function in Patients With Lower Extremity Ischemia 
Archives of internal medicine  2006;166(18):1986-1992.
Background
We determined whether lower extremity ischemia, as measured by the ankle brachial index (ABI), is associated with impaired lower extremity nerve function.
Methods
Participants included 478 persons with peripheral arterial disease (PAD) identified from noninvasive vascular laboratories and 292 persons without PAD identified from a general medicine practice and noninvasive vascular laboratories. Peripheral arterial disease was defined as an ABI lower than 0.90 (mild PAD: ABI, 0.70 to <0.90; moderate PAD: ABI, 0.50 to <0.70; and severe PAD: ABI, <0.50). The ABI and electrophysiologic measures of the peroneal, sural, and ulnar nerves were obtained.
Results
Among 546 participants without diabetes, PAD participants had significantly impaired peripheral nerve function in the upper and lower extremities compared with non-PAD participants. After adjusting for age, sex, race, smoking, height, body mass index, recruitment source, alcohol use, disk disease, spinal stenosis, cardiac disease, and cerebrovascular disease, these associations were not statistically significant. After adjusting for confounders among nondiabetic participants, those with severe PAD (ABI, <0.50) had poorer peroneal nerve conduction velocity (NCV) compared with participants without PAD (42.6 vs 44.8 m/s; P=.003) and poorer peroneal NCV compared with participants with mild PAD (42.6 vs 45.0 m/s; P=.001) or moderate PAD (42.6 vs 44.1 m/s; P=.03). Among 224 participants with diabetes, after adjusting for confounders, PAD was associated with poorer peroneal NCV (40.8 vs 43.5 m/s; P=.01), sural nerve amplitude (3.1 vs 4.8 μV; P=.045), and ulnar NCV (47.6 vs 50.2 m/s; P=.03) compared with those without PAD.
Conclusions
Our findings suggest that leg ischemia impairs peroneal nerve function. This association is less strong in patients with diabetes, perhaps because of the overriding influence of diabetes on peripheral nerve function. Clinicians should consider screening for PAD in patients with idiopathic peroneal nerve dysfunction. Peripheral arterial disease–associated nerve dysfunction may contribute to PAD-associated functional impairment.
doi:10.1001/archinte.166.18.1986
PMCID: PMC2645651  PMID: 17030832
25.  Functional MRI in Peripheral Arterial Disease: Arterial Peak Flow versus Ankle-Brachial Index 
PLoS ONE  2014;9(2):e88471.
Objectives
The purpose of this study was to compare the success rate of successful arterial peak flow (APF) and ankle-brachial index (ABI) measurements in patients with suspected or known peripheral arterial disease (PAD).
Materials and Methods
183 patients with varying degrees of PAD were included. All subjects underwent ABI measurements and MR imaging of the popliteal artery to determine APF. Proportions of patients with successful APF and ABI measurements were compared and the discriminative capability was evaluated.
Results
APF was successfully measured in 91% of the patients, whereas the ABI could be determined in 71% of the patients (p<0.01). Success rates of APF and ABI were significantly higher in patients with intermittent claudication (95% and 80%, respectively) than in patients with critical ischemia (87% and 62%, respectively).
Conclusions
Compared to the assessment of PAD severity with ABI, the success rate of MRI-based APF measurements in patients with a clinical indication for MRA is 20% higher, with similar discriminatory capacity for disease severity. Therefore, APF is an especially convenient and valuable measure to assess severity in PAD patients scheduled to undergo MR angiography to obtain additional functional information concerning the vascular status.
doi:10.1371/journal.pone.0088471
PMCID: PMC3914999  PMID: 24505494

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