Automated ankle-brachial pressure index measurement by clinical staff for peripheral arterial disease diagnosis in nondiabetic and diabetic patients

Current Opinion on Diagnosis of Peripheral Artery Disease in Diabetic Patients

Peripheral arterial disease (PAD) prevalence and diabetes mellitus (DM) prevalence are continuously increasing worldwide. The strong relationship between DM and PAD is highlighted by recent evidence. PAD diagnosis in diabetic patients is very important, particularly in patients with diabetic foot disease (DFD); however, it is often made difficult by the characteristics of such diseases. Diagnosing PAD makes it possible to identify patients at a very high cardiovascular risk who require intensive treatment in terms of risk factor modification and medical therapy. The purpose of this review is to discuss the diagnostic methods that allow for a diagnosis of PAD in diabetic patients. Non-invasive tests that address PAD diagnosis will be discussed, such as the ankle-brachial index (ABI), toe pressure (TP), and transcutaneous oxygen pressure (TcPO2). Furthermore, imaging methods, such as duplex ultrasound (DUS), computed tomography angiography (CTA), magnetic resonance angiography (MRA), and digital subtraction angiography (DSA), are described because they allow for diagnosing the anatomical localization and severity of artery stenosis or occlusion in PAD. Non-invasive tests will also be discussed in terms of their ability to assess foot perfusion. Foot perfusion assessment is crucial in the diagnosis of critical limb ischemia (CLI), the most advanced PAD stage, particularly in DFD patients. The impacts of PAD diagnosis and CLI identification in diabetic patients are clinically relevant to prevent amputation and mortality.

Correlation of ankle-wrist pressure index with ankle-brachial pressure index to assess lower limb perfusion in diabetic foot ulcer: a pilot study

OBJECTIVE

The presence of peripheral artery disease (PAD) in patients with diabetic foot ulcers (DFUs) is a significant risk factor for chronicity and amputation. Ankle-brachial pressure index (ABPI) is a screening tool for PAD. Brachial systolic pressure measurement, used as a denominator in the calculation of ABPI, produces inaccurate results in patients with obesity and the presence of heavy clothing. The wrist, however, is easily accessible, and the ankle-wrist pressure index (AWPI), if comparable with ABPI, may be useful in screening selected patients. This study aimed to assess the efficacy of AWPI in diagnosing perfusion in DFUs and compare it to ABPI in patients with DFUs.

METHOD

ABPI and AWPI were calculated by measuring systolic blood pressure in the arteries of the ankle, arm and wrist with a handheld Doppler. Actual perfusion was determined by the presence or absence of PAD by duplex ultrasound.

RESULTS

A total of 46 lower extremities in 41 patients were studied. The prevalence of PAD was 61%. Duplex ultrasound confirmed that the sensitivity of ABPI and AWPI in detecting PAD in patients with DFUs was 67.9% and 71.4% respectively, whereas the specificity of ABPI and AWPI was 94.4% and 88.9% respectively. On receiver operating characteristic analysis, the area under the curve of ABPI and AWPI was 0.804 and 0.795, respectively. A statistically significant positive correlation between ABPI and AWPI was found (r=0.986; p<0.001).

CONCLUSION

There was a good correlation between ABPI and AWPI over a wide range of values. ABPI and AWPI may have a similar role in predicting perfusion in patients with DFUs. AWPI could be used in place of ABPI in selected patients in whom measuring ABPI may be difficult.

DECLARATION OF INTEREST

The authors have no conflicts of interest to declare.

Diagnosis of disease affecting gait with a body acceleration-based model using reflected marker data for training and a wearable accelerometer for implementation

This paper demonstrates the value of a framework for processing data on body acceleration as a uniquely valuable tool for diagnosing diseases that affect gait early. As a case study, we used this model to identify individuals with peripheral artery disease (PAD) and distinguish them from those without PAD. The framework uses acceleration data extracted from anatomical reflective markers placed in different body locations to train the diagnostic models and a wearable accelerometer carried at the waist for validation. Reflective marker data have been used for decades in studies evaluating and monitoring human gait. They are widely available for many body parts but are obtained in specialized laboratories. On the other hand, wearable accelerometers enable diagnostics outside lab conditions. Models trained by raw marker data at the sacrum achieve an accuracy of 92% in distinguishing PAD patients from non-PAD controls. This accuracy drops to 28% when data from a wearable accelerometer at the waist validate the model. This model was enhanced by using features extracted from the acceleration rather than the raw acceleration, with the marker model accuracy only dropping from 86 to 60% when validated by the wearable accelerometer data.

Ankle-Brachial Index: Diagnostic Tool of Peripheral Arterial Disease and Predictor of Cardiovascular Risk-An Update of Current Knowledge

The ankle-brachial index (ABI) was introduced as a screening method for the diagnosis of lower extremity peripheral arterial disease (PAD). Later findings recognized ABI as a prognostic marker of adverse cardiovascular events due to its relation to atherosclerosis in other vascular territories. This narrative review aims to appraise the validity, reliability, and utility of ABI in the detection of PAD and the determination of global atherosclerotic cardiovascular risk. While the ABI value can be influenced by different physiological characteristics including age, sex, body position, and techniques used for ABI determination, it has high specificity and reproducibility in the assessment of vascular patients. In conclusion, when used correctly, the ABI remains a reliable and invaluable indicator of lower-limb perfusion and a useful tool for predicting the risk of future cardiovascular events. However, its underutilization in clinical settings is noteworthy.

Oscillometric measurement of the ankle-brachial index and the estimated carotid-femoral pulse wave velocity improves the sensitivity of an automated device in screening peripheral artery disease

Background and aims

To overcome the time and personnel constraints of the Doppler method, automated, four-limb blood pressure monitors were recently developed. Their additional functions, such as measuring the estimated carotid-femoral pulse wave velocity (ecfPWV), have been, thus far, less studied. We aimed to compare the sensitivity and specificity of different ankle-brachial index (ABI), toe-brachial index (TBI), and ecfPWV measurement methodologies to evaluate their contribution to peripheral artery disease (PAD) screening.

Methods

Among 230 patients (mean age 64 ± 14 years), ABI measurements were performed using a Doppler device and a manual sphygmomanometer. The Doppler ABI was calculated by taking the higher, while the modified Doppler ABI by taking the lower systolic blood pressure of the two ankle arteries as the numerator, and the higher systolic blood pressure of both brachial arteries as the denominator. The automated ABI measurement was carried out using an automatic BOSO ABI-system 100 PWV device, which also measured ecfPWV. TBI was obtained using a laser Doppler fluxmeter (Periflux 5000) and a photoplethysmographic device (SysToe). To assess atherosclerotic and definitive PAD lesions, vascular imaging techniques were used, including ultrasound in 160, digital subtraction angiography in 66, and CT angiography in four cases.

Results

ROC analysis exhibited a sensitivity/specificity of 70.6%/98.1% for the Doppler ABI (area under the curve, AUC = 0.873), 84.0%/94.4% for the modified Doppler ABI (AUC = 0.923), and 61.5%/97.8% for the BOSO ABI (AUC = 0.882) at a cutoff of 0.9. Raising the cutoff to 1.0 increased the sensitivity of BOSO to 80.7%, with the specificity decreasing to 79.1%. The ecfPWV measurement (AUC = 0.896) demonstrated a 63.2%/100% sensitivity/specificity in predicting atherosclerotic lesions at a cutoff of 10 m/s. Combining BOSO ABI and ecfPWV measurements recognized 89.5% of all PAD limbs.

Conclusion

The combined BOSO ABI and ecfPWV measurements may help select patients requiring further non-invasive diagnostic evaluation for PAD. The user-friendly feasibility may make it suitable for screening large populations.

Incoherent optical fluctuation flowmetry for detecting limbs with hemodynamically significant stenoses in patients with type 2 diabetes

INTRODUCTION

The development of new highly accurate, inexpensive and accessible methods for the detection of lower-extremity peripheral artery disease (LE-PAD) in diabetic patients is required. The aim of this study was to evaluate the accuracy of a new incoherent optical fluctuation flowmetry (IOFF) method in detecting legs with hemodynamically significant stenoses compared to ankle brachial index (ABI) and transcutaneous oximetry (TcPO2) in patients with diabetes mellitus (DM).

MATERIALS AND METHODS

Patients were recruited into 2 groups. Group 1 included patients with DM without LE-PAD and/or diabetic foot syndrome; Group 2 included patients with DM and LE-PAD. All patients underwent the following measurements: ultrasound (reference method), ABI, TcPO2, and the new IOFF method.

RESULTS

The new IOFF method showed a sensitivity of 79.5% and a specificity of 89.8% in detecting limbs with hemodynamically significant stenosis (AUC 0.890, CI 0.822-0.957). TcpO2 allows the diagnosis of LE-PAD with 69.2% sensitivity and 86.2% specificity (AUC 0.817, CI 0.723-0.911). Using a standard ABI cut-off of less than 0.9, the sensitivity and specificity for this parameter were 34.5% and 89.7%, respectively. Increasing the diagnostic cut-off of the ABI on the study group to 0.99 improved sensitivity to 84.6% and specificity to 78% (AUC,0.824 CI 0.732-0.915).

CONCLUSIONS

The new IOFF technique has demonstrated high sensitivity and specificity in the detection of LE-PAD in patients with DM. The high accuracy, rapid measurement, and potential availability suggest that the new IOFF method has a high potential for clinical application in the detection of PAD.

Screening for Peripheral Artery Disease Using an Automated Four-Limb Blood Pressure Monitor Equipped with Toe-Brachial Index Measurement

Toe-brachial index (TBI) measurement helps to detect peripheral artery disease (PAD) in patients with incompressible ankle arteries due to medial arterial calcification, which is most frequently associated with diabetes. We aimed to evaluate how an automated four-limb blood pressure monitor equipped with TBI measurement could contribute to PAD screening. In 117 patients (mean age 63.2 ± 12.8 years), ankle-brachial index (ABI) measurement was performed using the Doppler-method and the MESI mTablet. TBI was obtained via photoplethysmography (MESI mTablet, SysToe) and a laser Doppler fluxmeter (PeriFlux 5000). Lower limb PAD lesions were evaluated based on vascular imaging. A significant correlation was found between Doppler and MESI ankle-brachial index values (r = 0.672), which was stronger in non-diabetic (r = 0.744) than in diabetic (r = 0.562) patients. At an ABI cut-off of 0.9, Doppler (AUC = 0.888) showed a sensitivity/specificity of 67.1%/97.4%, MESI (AUC 0.891) exhibited a sensitivity/specificity of 57.0%/100%; at a cut-off of 1.0, MESI demonstrated a sensitivity/specificity of 74.7%/94.8%. The TBI values measured using the three devices did not differ significantly (p = 0.33). At a TBI cut-off of 0.7, MESI (AUC = 0.909) revealed a sensitivity/specificity of 92.1%/67.5%. Combining MESI ABI and TBI measurements recognised 92.4% of PAD limbs. Using an ABI cut-off level of 1.0 and sequential TBI measurement increases the sensitivity of the device in detecting PAD. The precise interpretation of the obtained results requires some expertise.

Machine Learning-Based Peripheral Artery Disease Identification Using Laboratory-Based Gait Data

Peripheral artery disease (PAD) manifests from atherosclerosis, which limits blood flow to the legs and causes changes in muscle structure and function, and in gait performance. PAD is underdiagnosed, which delays treatment and worsens clinical outcomes. To overcome this challenge, the purpose of this study is to develop machine learning (ML) models that distinguish individuals with and without PAD. This is the first step to using ML to identify those with PAD risk early. We built ML models based on previously acquired overground walking biomechanics data from patients with PAD and healthy controls. Gait signatures were characterized using ankle, knee, and hip joint angles, torques, and powers, as well as ground reaction forces (GRF). ML was able to classify those with and without PAD using Neural Networks or Random Forest algorithms with 89% accuracy (0.64 Matthew's Correlation Coefficient) using all laboratory-based gait variables. Moreover, models using only GRF variables provided up to 87% accuracy (0.64 Matthew's Correlation Coefficient). These results indicate that ML models can classify those with and without PAD using gait signatures with acceptable performance. Results also show that an ML gait signature model that uses GRF features delivers the most informative data for PAD classification.

Reliability of bedside tests for diagnosing peripheral arterial disease in patients prone to medial arterial calcification: A systematic review

BACKGROUND

Medial arterial calcification (MAC), frequently associated with diabetes mellitus (DM) and chronic kidney disease (CKD), is a systemic vascular disorder leading to stiffness and incompressible arteries. These changes impede the accuracy of bedside tests to diagnose peripheral arterial disease (PAD). This review aimed to evaluate the reliability of bedside tests for the detection of PAD in patients prone to MAC.

METHODS

A systematic search (Pubmed, Embase, Web of Science, Cochrane, and Emcare) was performed according to the PRISMA guidelines to identify relevant studies providing data on the performance of bedside tests for the detection of PAD in patients prone to MAC. Studies were included when bedside test were compared to a reference standard. Primary endpoints were the positive and negative likelihood ratios (PLR, NLR). Methodological quality and risk of bias were evaluated using the QUADAS-2 tool.

FINDINGS

In total, 23 studies were included in this review. The most commonly evaluated test was the ankle-brachial index (ABI), followed by toe-brachial index (TBI), toe pressure (TP) measurements, and continuous wave Doppler (CWD). The majority of patients were older, male, and had DM. We found that ABI <0·9 was helpful to diagnose PAD, but failed to rule out PAD (NLR >0·2). The same applied for TP (NLR >0·3) and TBI (5 out of 6 studies revealed an NLR >0·2). CWD (loss of triphasic pattern) is reliable to exclude PAD (NLR 0-0·09), but was only validated in two studies. Overall, methodological quality was poor which led to risk of bias in 20 studies.

INTERPRETATION

The diagnosis of PAD in patients prone to MAC remains challenging. The ABI performed reasonably in the diagnosis of PAD, while the CWD (loss of triphasic signal) can be used to rule out PAD. This systematic review showed that test performances were generally poor with serious concerns in methodological quality of the included studies. We therefore counsel against the use of a single bedside test.

FUNDING

None to declare.

Guidelines and standards for comprehensive clinical diagnosis and interventional treatment for diabetic foot in China (Issue 7.0)

Diabetic foot (DF) is one of the most common complications of diabetes and is associated with high morbidity, disability, lethality and low cure-rate. The clinical diagnosis and treatment of DF need to be standardized. The Chinese Diabetic Foot Cell and Interventional Therapy Technology Alliance has released six editions of guidelines and standards for clinical diagnosis and interventional treatment of DF, which filled the gap in the domestic DF treatment standard and played an important role in improving the level of diagnosis and treatment in China. In line with the latest developments in diagnosis and treatment, the Alliance, along with other 89 institutions, developed and issued the new edition based on the sixth edition to help standardize the clinical diagnosis and treatment of DF in China.

Combination of Exercise Testing Criteria to Diagnose Lower Extremity Peripheral Artery Disease

Objectives: Nothing is known about the interest of the combination of exercise tests to diagnose Lower-extremity Peripheral Artery Disease (LEPAD). The aim of this study was to assess if combining exercise testing criteria [post-exercise Ankle-Brachial Index (ABI) + exercise-oximetry (exercise-TcPO2)] improves the detection of lower limbs arterial stenoses as compared with post-exercise ABI using American Heart Association (AHA) criteria, or exercise-TcPO2 alone. Material and Methods: In a prospective monocentric study, consecutive patients with exertional-limb pain and normal resting-ABI referred to our vascular center (Rennes, France) were assessed from May 2016 to February 2018. All included patients had a computed tomography angiography (CTA), a resting-ABI, a post-exercise ABI and an exercise-TcPO2. AHA post-exercise criteria, new validated post-exercise criteria (post-exercise ABI decrease ≥18.5%, post-exercise ABI decrease <0.90), and Delta from Rest of Oxygen Pressure (Total-DROP) ≤-15mmHg (criterion for exercise-TcPO2) were used to diagnose arterial stenoses ≥50%. For the different combinations of exercise testing criteria, sensitivity or specificity or accuracies were compared with McNemar's test. Results: Fifty-six patients (mean age 62 ± 11 years old and 84% men) were included. The sensitivity of the combination of exercise testing criteria (post-exercise ABI decrease ≥18.5%, or post-exercise ABI decrease <0.90 or a Total-DROP ≤-15mmHg) was significantly higher (sensitivity = 81% [95% CI, 71-92]) than using only one exercise test (post-exercise AHA criteria (sensitivity = 57% [43-70]) or exercise-TcPO2 alone (sensitivity = 59% [45-72]). Conclusions: Combination of post-exercise ABI with Exercise-TcPO2 criteria shows better sensitivity to diagnose arterial stenoses compared with the AHA post-exercise criteria alone or Exercise-TcPO2 criteria used alone. A trend of a better accuracy of this combined strategy was observed but an external validation should be performed to confirm this diagnostic strategy.

Automated Measurements of Ankle-Brachial Index: A Narrative Review

Peripheral artery disease (PAD) is an atherosclerotic disease that causes obstruction in lower limb arteries. It increases cardiovascular risk even in asymptomatic patients. Accurate diagnostic tools for identification of affected individuals are needed. Recently, there have been attempts to establish a reliable method of automated ankle-brachial index (ABI) identification. A search of PubMed database to identify studies assessing automatic ABI measurements in agreement with standard PAD diagnosis methods was conducted in December 2020. A total of 57 studies were analyzed in the review. The majority of analyzed studies found ABI measured by automatic oscillometric devices to be potentially feasible for use. Some note that, even though the Doppler and oscillometric methods are not fully interchangeable, the oscillometric devices could be used in screening. Significantly fewer publications are available on automatic plethysmographic devices. For photoplethysmography, most studies reported either good or moderate agreement with reference standards. For air plethysmography, poorer agreement with Doppler ABI is suggested. It is noted that pulse volume recording (PVR) function may improve the diagnostic accuracy of the devices.

Subclinical atherosclerosis in the carotid artery: can the ankle-brachial index predict it in type 2 diabetes patients?

Atherosclerosis is a progressive asymmetrical systemic disease that progresses faster in patients with diabetes comorbidity. Therefore, type 2 diabetic (T2DM) patients who have a high risk of, or have already detected, early atherosclerosis should be treated aggressively to prevent premature mortality. We hypothesised that subclinical atherosclerosis is predictable with the ankle-brachial index (ABI). There are currently only a few studies to indicate which specific value of ABI can predict atherosclerosis in the carotid artery. Our study aimed to examine ABI ≤ 1.1 ability to predict ultrasound-visualised atherosclerosis in carotid arteries in patients with T2DM, who had not been previously diagnosed with atherosclerosis. A population-based cross-sectional multicentric study was performed in 216 participants (mean age 59 ± 8 years). Carotid artery intima-medial thickness (IMT) ≥1 mm ± plaque was defined as a marker for subclinical atherosclerosis and was compared with ABI. Mean duration of T2DM was 7.05 ± 6.0 years. Atherosclerosis in the carotid artery was found in 96 (44%) patients, with no significant differences between genders (47 vs 53%, p = .206). ABI ≤1.1 was associated with the carotid artery mean IMT ≥1 mm (p = .037), plaque (p = .027) and IMT ≥1 mm ± plaque (p = .037). The association between ABI ≤ 1.1 and IMT ≥ 1 mm ± plaque remained significant after adjustment for risk factors and age >50 years. Observations demonstrated that ABI ≤ 1.1 could be an indicator of subclinical atherosclerosis for T2DM male patients over 50 years old.

Estimating the diagnostic accuracy of the ankle-brachial pressure index for detecting peripheral arterial disease in people with diabetes: A systematic review and meta-analysis

AIM

To systematically evaluate research investigating the accuracy of the ankle-brachial index (ABI) for diagnosing peripheral artery disease (PAD) in people with diabetes, as the accuracy is thought to be reduced in this cohort.

METHODS

A database search of EBSCO Megafile Premier, Embase and The Cochrane Library was conducted to 28 February 2019. Prospective and retrospective investigations of the diagnostic accuracy of the ABI for PAD in people with diabetes using an imaging reference standard were eligible. Sensitivity and specify of the ABI and bivariate meta-analysis against reference tests, or a standard summary receiver operating curve analysis (SROC) was performed.

RESULTS

Thirty-three studies met the inclusion criteria. ABI was compared with angiography in 12 studies and with colour duplex ultrasound (CDUS) in 21 studies. A SROC analysis of studies using angiography as the reference standard found a diagnostic odds ratio (DOR) of 9.06 [95% confidence interval (CI) 3.61 to 22.69], and area under the curve (AUC) of 0.76 (95% CI 0.66 to 0.86). Bivariate analysis of studies using CDUS demonstrated mean sensitivity of 0.60 (95% CI 0.48 to 0.71; P = 0.097) and mean specificity of 0.87 (95% CI 0.78 to 0.92; P < 0.001) with a DOR of 9.76 (95% CI 5.24 to 18.20; P < 0.0001) and AUC 0.72.

CONCLUSIONS

These results suggest the ABI has a high specificity but lower sensitivity in detecting imaging diagnosed PAD in people with diabetes. The low probability of the testing being able to rule diagnosis in or out suggest that the ABI has limited effectiveness for early detection of PAD in this cohort.

[Mönkeberg's sclerosis: role of calcification in arterial lesions in patients with diabetes mellitus]

The number of patients with diabetes mellitus has steadily been increasing. This disease is associated with the risk for the development of micro- and macroangiopathies. One of the variants of macroangiopathy is Mönkeberg's sclerosis characterized by the presence of calcification of the media of the arterial wall. This article is a literature review reflecting the role of calcification in arterial lesions in patients with diabetes mellitus, also covering the historical aspect of studying Mönkeberg's sclerosis. Special attention is paid to its morphological forms, aetiopathogenetic mechanisms of development, taking into account contemporary studies, demonstrating mechanisms of the effect of medial arterial calcification on haemodynamics and the risk for the development of cardiovascular complications. Also presented herein are the main non-invasive and invasive methods of its diagnosis.

A systematic review and meta-analysis of the diagnostic accuracy of point-of-care tests used to establish the presence of peripheral arterial disease in people with diabetes

OBJECTIVE

No agreement has been reached regarding which bedside test is the most useful for the diagnosis of peripheral arterial disease (PAD) in patients with diabetes. The aim of the present systematic review and meta-analysis was to evaluate the performance of bedside tests for the detection of PAD in individuals with diabetes.

METHODS

MEDLINE and EMBASE databases were systematically searched for studies providing data on the diagnostic performance of bedside tests used for the detection of PAD in those with diabetes. A meta-analysis was performed to obtain pooled estimates of sensitivity and specificity for the diagnosis of PAD.

RESULTS

A total of 18 studies, reporting on a total of 3016 limbs of diabetic patients, were included in our qualitative review. Of these, 11 studies (1543 limbs) were included in the meta-analysis of diagnostic accuracy: ankle-brachial pressure index (9 studies and 1368 limbs; sensitivity, 63.5% [95% confidence interval (CI), 51.7%-73.9%]; specificity, 89.3% [95% CI, 81.1%-94.2%]); toe-brachial pressure index (3 studies and 221 limbs; sensitivity, 83.0% [95% CI, 59.1-94.3%]; specificity, 66.3% [95% CI, 41.3%-84.6%]); and tibial waveform assessment (4 studies and 397 limbs; sensitivity, 82.8% [95% CI, 73.3%-89.4%], specificity, 86.8% [95% CI, 75.5%-93.3%]). Overall, we found a high risk of bias across the studies, most frequently relating to patient selection and the lack of blinding.

CONCLUSIONS

The toe-brachial pressure index, pulse oximetry, and tibial arterial waveform assessment demonstrated some promise, warranting further investigation.

Macrovascular Complications of Type 2 Diabetes Mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) has emerged as a pandemic. It has different complications, both microvascular and macrovascular.

OBJECTIVE

The purpose of this review is to summarize the different types of macrovascular complications associated with T2DM.

METHODS

A comprehensive review of the literature was performed to identify clinical studies, which determine the macrovascular complications associated with T2DM.

RESULTS

Macrovascular complications of T2DM include coronary heart disease, cardiomyopathy, arrhythmias and sudden death, cerebrovascular disease and peripheral artery disease. Cardiovascular disease is the primary cause of death in diabetic patients. Many clinical studies have shown a connection between T2DM and vascular disease, but almost always other risk factors are present in diabetic patients, such as hypertension, obesity and dyslipidaemia.

CONCLUSION

T2DM causes a variety of macrovascular complications through different pathogenetic pathways that include hyperglycaemia and insulin resistance. The association between T2DM and cardiovascular disease is clear, but we need more clinical studies in order to identify the pure effect of T2DM.

Accuracy and Reliability of the Ankle Brachial Index Measurement Using a Multicuff Oscillometric Device Versus the Doppler Method

OBJECTIVE

Ankle brachial index (ABI) is widely used for the diagnosis of lower extremity artery disease (LEAD). The purpose of this prospective study was to validate the diagnostic ability and reproducibility of a four cuff automated oscillometric device vs. the Doppler method.

METHODS

Patients with suspected LEAD or asymptomatic individuals at risk because of the presence two or more cardiovascular risk factors were enrolled. For each patient, Doppler and oscillometric ABI measurements were repeated by two observers to address intra- and interobserver reproducibility.

RESULTS

In total, 118 patients were evaluated. The prevalence of Doppler ABI (Dop-ABI) ≤ 0.90 was 45.8%. Taking the Dop-ABI as the reference, the sensitivity, specificity, accuracy, positive and negative predictive values of oscillometric ABI (Osc-ABI) during the first measurement by the first observer were 89.1%, 94.4%, 94.1%, 91.8%, and 92.4%, respectively. The concordance for diagnosing ABI ≤0.90 between methods was excellent (kappa coefficients ranging from 0.80 to 0.88 with different observers). Intra-observer reproducibility assessed by intraclass correlation coefficient (ICC) between methods were 0.94 for observer 1 and 0.96 for observer 2. The intra-observer reproducibility using the same method was also excellent (ICC 0.94, 95% confidence interval [CI] 0.91-0.95) for Dop-ABI and 0.95 (95% CI 0.93-0.97) for Osc-ABI). The ICC for interobserver reproducibility using the same method was 0.95 (95% CI 0.92-0.96) for Dop-ABI and 0.96 (95% CI 0.94-0.97) for Osc-ABI.

CONCLUSION

This study validates the excellent diagnostic performances of a four cuff oscillometric device specifically designed for screening for LEAD. The simple measurement method could therefore be advocated in primary care where fast, easy, and reliable methods are suitable.

Diagnostic accuracy of automated oscillometric determination of the ankle-brachial index in peripheral artery disease

OBJECTIVE

Peripheral artery disease (PAD) is underdiagnosed in primary care settings, partly because of limited accuracy of the Doppler ankle-brachial index (ABI). This study aimed to assess the diagnostic accuracy of an automated oscillometric ABI device compared with reference standard vascular laboratory Doppler ABI equipment and to examine the influence of oscillometric errors on performance.

METHODS

Consecutive patients who were referred to a large general hospital for an ABI measurement were invited to participate. In each patient, the oscillometric analysis was followed by the Doppler analysis. Legs with incompressible ankle arteries were excluded from analysis. ABI values were compared using the Bland-Altman method. Oscillometric errors were defined as the incapacity of the oscillometer to report a value of ABI. A receiver operating characteristic curve was constructed, and the area under the curve was computed.

RESULTS

A total of 201 patients participated. The Bland-Altman plot showed a mean difference of 0.05 ± 0.12 (limits of agreement, -0.20 to 0.29), representing a small ABI overestimation after oscillometry. Oscillometric errors occurred more commonly in limbs with PAD than in limbs without PAD (28% and 7%, respectively; P < .001). Considering a 0.9 threshold and after oscillometric error exclusion, the oscillometric ABI showed a 74% sensitivity and a 97% specificity for a diagnosis of PAD. When oscillometric errors were considered as abnormal ABIs, sensitivity increased to 86% and specificity was maintained at 95%. The receiver operating characteristic curve showed an area under the curve of 0.96. The best oscillometric ABI cutoff point was 1.00. Using this threshold and when considering oscillometric errors as abnormal ABIs, sensitivity improved to 94% while maintaining specificity at 92%.

CONCLUSIONS

Oscillometric ABI showed good diagnostic accuracy compared with the reference standard. However, the high incidence of oscillometric errors and the challenges to correctly interpret readings may limit the use of the oscillometric method in PAD diagnosis.

Discordant Values in Lower Extremity Physiologic Studies Predict Increased Cardiovascular Risk

Background

Ankle‐brachial indexes (ABI) are a noninvasive diagnostic tool for peripheral arterial disease and a marker of increased cardiovascular risk. ABI is calculated using the highest systolic blood pressure of the 4 ankle arteries (bilateral dorsalis pedis and posterior tibial). Accordingly, patients may be assigned a normal ABI when the result would be abnormal if calculated using one of the other blood pressure readings. Cardiovascular outcomes for patients with discordant ABIs are undescribed.

Methods and Results

We performed a retrospective study of patients who underwent ABI measurement for any indication between January 1996 and June 2018. Those with normal ABIs (1.00–1.39) were included. We compared patients with all 4 normal ABIs (calculated using all 4 ankle arteries; n=15 577, median age 64.0 years, 54.4% men) to those with discordant ABIs (at least 1 abnormal ABI ≤0.99; n=2095, median age 66.0 years, 47.8% men). The outcomes assessed were ischemic stroke, myocardial infarction, and all‐cause mortality. Compared with patients with concordant normal ABIs, patients with discordant ABIs were older; women; smoked; and had chronic kidney disease, coronary artery disease, diabetes mellitus, chronic obstructive pulmonary disease, hypertension, or prior stroke. Patients with discordant ABIs had a greater risk of myocardial infarction (hazard ratio [HR], 1.31; 95% CI, 1.10–1.56), ischemic stroke (HR, 1.53; 95% CI, 1.37–1.72), and all‐cause mortality (HR, 1.27; 95% CI, 1.16–1.39), including after adjustment for baseline comorbidities.

Conclusions

Discordant ABI results were associated with an increased risk of myocardial infarction, stroke, and all‐cause mortality in the studied population. Clinicians should examine ABI calculations using all 4 ankle arteries to better characterize a patient's cardiovascular risk.

Non-invasive vascular assessment in people with type 2 diabetes: Diagnostic performance of Plethysmographic-and-Doppler derived ankle brachial index, toe brachial index, and pulse volume wave analysis for detection of peripheral arterial disease

OBJECTIVE

There is evidence that standard assessment techniques for detecting PAD might be of less diagnostic accuracy in people with type 2 diabetes. The aim of this study was to examine diagnostic performance of Plethysmographic-and-Doppler derived ankle brachial index, toe brachial index, and Pulse volume waveform analysis for detecting PAD in people with T2DM.

METHODS

In this cross-sectional study 303 patients with T2DM were included in the study. The participants underwent ABI measurement, applying both Plethysmographic and Doppler derived devices, as well as TBI, PVW was also recorded for each patient. Diagnostic performance of each test for detecting PAD, applying ultrasound Doppler scan as the reference standard, was measured. Moreover, the best cut-off point for each method to detect PAD was determined.

RESULTS

PVW showed the highest sensitivity (81.8%) for detecting PAD, followed by ABI_DOP (72.7%), and ABI_PLE (20%). However, all devices showed an excellent specificity for detecting PAD. The optimal cut-off point for diagnosis of PAD was 0.9 for ABI_DOP, 1.2 for ABI_PLE, and 0.38 for TBI.

CONCLUSION

Within this population of patients with T2DM, TBI less than 0.38 provided the best sensitivity for detection of PAD followed by PVW, ABI_DOP≤0.9, and ABI_PLE<1.2.

Use of Noncontact Infrared Skin Thermometer for Peripheral Arterial Disease Screening in Patients With and Without Diabetes

Peripheral arterial disease (PAD) poses a threat of limb amputation and cardiovascular events. However, PAD diagnostic procedure requiring time, cost, and technical skills preclude its application as a screening test in the general population. Although PAD tends to be associated with lower foot skin temperature, none has yet to appreciate its usefulness for diagnosis/screening. We measured foot skin temperatures at the first and fifth metatarsal head and heel areas using noncontact infrared thermometer at the time of ankle brachial pressure index (ABI) measurement and limb arterial ultrasonography in 176 patients (345 legs) in participants. Foot skin temperatures correlated with ABI and showed distinctly lower levels in legs with ultrasound-confirmed arterial stenosis/occlusion and in those with ABI ≤0.90. Receiver operating characteristics analyses revealed that the lowest temperature value of the 3-foot locations had a higher sensitivity than every single location in detecting lower extremity PAD. Diagnostic efficiency for the ABI cutoff of 0.90 showed sensitivity/specificity of 41%/94%, while that for the lowest skin temperature cutoff of 30.8°C showed sensitivity/specificity of 60%/64%. In conclusion, an accurate skin temperature measurement using noncontact handheld infrared skin thermometer could serve as a new, cost-effective screening strategy for earlier diagnosis of PAD.

Effectiveness of bedside investigations to diagnose peripheral artery disease among people with diabetes mellitus: A systematic review

The accurate identification of peripheral artery disease (PAD) in patients with diabetes and foot ulceration is important, in order to inform timely management and to plan intervention including revascularisation. A variety of non-invasive tests are available to diagnose PAD at the bedside, but there is no consensus as to the most useful test, or the accuracy of these bedside investigations when compared to reference imaging tests such as magnetic resonance angiography, computed tomography angiography, digital subtraction angiography or colour duplex ultrasound. Members of the International Working Group of the Diabetic Foot updated our previous systematic review, to include all eligible studies published between 1980 and 2018. Some 15 380 titles were screened, resulting in 15 eligible studies (comprising 1563 patients, of which >80% in each study had diabetes) that evaluated an index bedside test for PAD against a reference imaging test. The primary endpoints were positive likelihood ratio (PLR) and negative likelihood ratio (NLR). We found that the most commonly evaluated test parameter was ankle brachial index (ABI) <0.9, which may be useful to suggest the presence of PAD (PLR 6.5) but an ABI value between 0.9 and 1.3 does not rule out PAD (NLR 0.31). A toe brachial index >0.75 makes the diagnosis of PAD less likely (NLR 0.14-0.24), whereas pulse oximetry may be used to suggest the presence of PAD (if toe saturation < 2% lower than finger saturation; PLR 17.23-30) or render PAD less likely (NLR 0.2-0.27). We found that the presence of triphasic tibial waveforms has the best performance value for excluding a diagnosis of PAD (NLR 0.09-0.28), but was evaluated in only two studies. In addition, we found that beside clinical examination (including palpation of foot pulses) cannot reliably exclude PAD (NLR 0.75), as evaluated in one study. Overall, the quality of data is generally poor and there is insufficient evidence to recommend one bedside test over another. While there have been six additional publications in the last 4 years that met our inclusion criteria, more robust evidence is required to achieve consensus on the most useful non-invasive bedside test to diagnose PAD.

Dynamic Volume Perfusion CT of the Foot in Critical Limb Ischemia: Response to Percutaneous Revascularization

OBJECTIVE. The purpose of this study was to assess the reproducibility and validity of quantitative perfusion parameters derived from dynamic volume perfusion CT in patients with critical limb ischemia (CLI) and to evaluate perfusion parameter changes before and after endovascular revascularization. SUBJECTS AND METHODS. Patients with CLI referred for unilateral extremity endovascular arterial recanalization were enrolled in this study. CT examinations obtained 1-3 days before the procedure and then within 1 week after the treatment were evaluated at two reading sessions. Blood flow (BF), blood volume (BV), and time to peak (TTP) were measured on color-coded maps and compared statistically. Intraobserver agreement was assessed using intraclass correlation coefficient (ICC) and Bland-Altman analysis. RESULTS. Endovascular treatment was technically successful for all 16 patients. The posttreatment BF and BV showed a statistically significant increase in both dermal and muscle areas (p < 0.05). The posttreatment TTP shortened at a statistically significant level (p < 0.05). In the 3-month clinical follow-up period, the limb salvage rate was 81% and the percentage change in BF and BV of patients with poor response to treatment had no statistically significant increase after treatment, consistent with the clinical assessment. The percentage change in BF and BV correlated well with the improvement of the clinical condition (r = 0.673-0.901). ICC values showed excellent agreement in the range of 0.95-0.98. CONCLUSION. As a reproducible method, dynamic volume perfusion CT of the foot may enable quantitative evaluation of the perfusion of soft tissues and also provide a novel approach to assessing response to endovascular recanalization in CLI.

Peripheral Arterial Disease: Supervised Exercise Therapy Through Cardiac Rehabilitation

Peripheral arterial disease (PAD) is frequently underdiagnosed and undertreated. This review identifies specific subgroups within older adults more likely to develop PAD, and describes methods to diagnose PAD and provide evidence in support of systematic referral to cardiac rehabilitation programs to enhance successful comprehensive management. Clear evidence and guidelines support the routine use of supervised exercise therapy to improve function, reduce risk of cardiovascular morbidity and mortality, and enhance the success of endovascular interventions.

Comparison of ankle-brachial index (ABI) measured by an automated oscillometric apparatus with that by standard hand-held doppler in patients with Type-2 diabetes

Objective:

To compare the difference between an automated oscillometric ABI measurement as compared to standard hand-held doppler ABI in patients with Type-2 diabetes.

Methods:

This prospective study was conducted at foot clinic of Baqai Institute of Diabetology and Endocrinology (BIDE), Baqai Medical University (BMU), a tertiary care unit, Karachi-Pakistan. The duration of study was February 2018 to March 2018. Patients with Type-2 diabetes attending the outpatient department (OPD) of foot clinic, irrespective of their symptoms were included. Baseline demographic, anthropometric measurements and biochemical parameters were recorded. The ABI was calculated with both devices by an automated oscillometric machine and standard hand-held doppler with the same investigator.

Results:

Total of 93 patients with Type-2 diabetes, 18 (19.4%) females and 75(80.6%) males were recruited. Mean age was 54.67±9.59 years and mean systolic/diastolic blood pressure was 131.38±20.2/ 80.36±10.23mmHg. Most of the patients had poor glycemic control at presentation with a mean HbA1c of 9.56±2.44%. Mean standard handheld doppler ABI and automated oscillometric ABI was 1.28±1.08 and 1.07±0.23 for right foot (mean difference = 0.21; P= 0.075), and 1.14±0.45 and 1.1±0.25 for left foot (mean difference =0.04; P=0.434), respectively. Similarly, sensitivity and specificity between two modalities was observed 60% and 93.90% for right foot, meanwhile, 60% and 97.40% for left foot, respectively.

Conclusion:

An automated oscillometric method is comparable with standard handheld-doppler method. It is cost effective, convenient and less time consuming, can be widely used to measure ABI without special training.

Ankle Brachial Pressure Index: An update for the vascular specialist and general practitioner

Objectives

Ankle brachial pressure index (ABPI) is an invaluable tool for assessing the severity of peripheral arterial disease. In addition, it can be used as an independent marker of cardiovascular risk, with a predictive ability similar to the Framingham criteria. Identification of an abnormal ABPI should therefore trigger aggressive cardiac risk factor modulation for a patient. Unfortunately, the significance of abnormal ABPIs is poorly understood within the general medical community. This is compounded by the influence of various comorbidities on accurate measurement of ABPI, potentially leading to a wide variability in readings that need to be considered before interpretation in these patient populations. We aim to address these issues by revealing several common misunderstandings and pitfalls in ABPI measurement, describing accurate methodology, and highlighting patient cohorts in whom additional or alternative approaches may be required.

Methods

We present a narrative review of the role of ABPI in both the community and hospital setting. We have performed a literature review, exploring the validity and reproducibility of methodology for obtaining ABPI, alongside the utility of ABPI in different clinical scenarios.

Results

The measurement of ABPI is often performed incorrectly. Common pitfalls include inadequate patient preparation, failure to obtain the blood pressure from the correct lower limb artery in patients with tibial disease, failure to account for differences in brachial blood pressure between the arms, inappropriately chosen equipment and patient factors such as highly calcified arteries. Standardisation of methodology greatly improves reliability of the test. Exercise ABPI can identify significant peripheral arterial disease in patients with normal resting ABPI. In addition to its role in peripheral arterial disease, ABPI measurement has a role in assessing venous ulcers, entrapment syndromes and injured extremities; conversely, it has a more limited utility in the diabetic population.

Conclusions

A thorough understanding of the correct technique and associated limitations of ABPI measurement is essential in accurately generating and interpreting the data it provides. With this knowledge, the ABPI is an invaluable tool to help manage patients with peripheral arterial disease. Perhaps more importantly, ABPI can be used to identify and risk stratify patients with asymptomatic peripheral arterial disease, itself a major indicator of significant underlying cardiovascular disease. With the emergence of best medical therapy, targeted pharmacotherapy and lifestyle changes can reduce the risk of major cardiovascular events in high-risk patients by approximately 30%, particularly in diabetic patients. Therefore, the utility of ABPI transgresses vascular surgery, with an essential role in general practice and public health.

Four-Limb Blood Pressure Measurement with an Oscillometric Device: a Tool for Diagnosing Peripheral Vascular Disease

PURPOSE OF REVIEW

Traditionally, the term peripheral vascular disease (PAD) is restricted to the occlusive arterial disease in the leg, but now, the connotation of PAD is more widespread as it encompasses all extracoronary and extracerebral vascular disease. The incidence of PAD is increasing worldwide; therefore, it is necessary to diagnose PAD at an early stage.

RECENT FINDINGS

Oscillometric BP device is widely used for four-limb measurement in clinical practice and provides several parameters for evaluating inter-limb BP difference, such as ankle-brachial index (OS-ABI), inter-arm BP differences (IAD), and inter-ankle BP difference (IAND). Using angiographic results as reference, the ABI, IAD, and IAND from an oscillometric BP device have been demonstrated having high accuracy for diagnosis of PAD. Meanwhile, combination of these parameters could further improve the accuracy of PAD, including the occlusive artery disease in the arm, leg, and aorta. For example, some patients with severe PAD in the leg have normal ABI; in this situation, an increased sIAND could confirm the diagnosis of PAD in the leg. Because ABI, IAD, and IAND from inter-limb oscillometric BP measurement can also predict adverse prognosis, we encourage the use of an oscillometric device to measure four-limb BP and to evaluate the inter-limb BP difference.

Low Bone Mineral Density Is Not Associated with Subclinical Atherosclerosis: A Population-Based Study in Rural China

OBJECTIVES

Loss of bone mass may affect the progression of atherosclerosis. We investigated the relationship between low bone mineral density (BMD) and subclinical atherosclerosis in rural China.

METHODS

In total, 333 men and 421 postmenopausal women aged 55-65 years were enrolled. BMD was measured in the lumbar spine, femoral neck, and total hip using dual-energy X-ray absorptiometry. Subclinical atherosclerosis was defined as increased carotid artery intima-media thickness (CIMT ≥0.9 mm), the presence of carotid plaques, high brachial-ankle pulse wave velocity (baPWV ≥1,400 cm/s), and low ankle-brachial index (ABI ≤1). Binary logistic regression analyses were used to estimate the association between low BMD and subclinical atherosclerosis.

RESULTS

There was no significant difference in BMD between the normal group and the subclinical atherosclerosis group. After full adjustment for the relevant covariates, a boundary significant association was found between low BMD in the femoral neck and baPWV in postmenopausal women (odds ratio = 1.77, p = 0.049). After full adjustment, neither BMD nor low BMD were significantly associated with subclinical atherosclerosis in men or postmenopausal women.

CONCLUSIONS

Low BMD is not associated with subclinical atherosclerosis in Chinese individuals aged 55-65 years resident in rural China.

Clinical examination and non-invasive screening tests in the diagnosis of peripheral artery disease in people with diabetes-related foot ulceration

AIM

Peripheral artery disease is common in people with diabetes-related foot ulceration and is a risk factor for amputation. The best method for the detection or exclusion of peripheral artery disease is unknown. This study investigated the utility of clinical examination and non-invasive bedside tests in screening for peripheral artery disease in diabetes-related foot ulceration.

METHODS

Some 60 people presenting with new-onset ulceration participated. Accuracy of pulses, ankle pressure, toe pressure, toe-brachial index (TBI), ankle-brachial pressure index (ABPI), pole test at ankle, transcutaneous oxygen pressure and distal tibial waveform on ultrasound were examined. The gold standard diagnostic test used was > 50% stenosis in any artery or monophasic flow distal to calcification in any ipsilateral vessel on duplex ultrasound.

RESULTS

The negative and positive likelihood ratios of pedal pulse assessment (0.75, 1.38) and the other clinical assessment tools were poor. The negative and positive likelihood ratios of ABPI (0.53, 1.69), transcutaneous oxygen pressure (1.10, 0.81) and ankle pressure (0.67, 2.25) were unsatisfactory. The lowest negative likelihood ratios were for tibial waveform assessment (0.15) and TBI (0.24). The highest positive likelihood ratios were for toe pressure (17.55) and pole test at the ankle (10.29) but the negative likelihood ratios were poor at 0.56 and 0.74.

CONCLUSIONS

Pulse assessment and ABPI have limited utility in the detection of peripheral artery disease in people with diabetes foot ulceration. TBI and distal tibial waveforms are useful for selecting those needing diagnostic testing.

Relationships between chronic comorbidities and the atherosclerosis indicators ankle-brachial index and brachial-ankle pulse wave velocity in patients with type 2 diabetes mellitus

This study aimed to determine associations between ankle-brachial index (ABI) and brachial-ankle pulse wave velocity (baPWV) with different comorbidities in patients with type 2 diabetes mellitus (DM). Records of patients with type 2 DM who received an ABI and baPWV examination between August 2013 and February 2015 were retrospectively reviewed. Associations of ABI and baPWV with chronic kidney disease (CKD), chronic liver disease (CLD), coronary artery disease (CAD) and diabetic nephropathy (DN) were examined by regression analysis. A total of 1232 patients (average age, 65.1±10.0 years) were included in the analysis. CKD and DN were associated with low ABI and increased baPWV (all, P<0.001). No associations were found between CAD and CLD and ABI or baPWV. Thus, regression analysis was performed for CKD and DN. Low ABI was associated with risk of CKD in the crude model (OR 0.724, 95% CI 0.648 to 0.808, P<0.001) and adjusted model (OR 0.872, 95% CI 0.762 to 0.999, P=0.048), whereas baPWV was only significant in the crude model (OR 1.199, 95% CI 1.112 to 1.294, P<0.001). Low ABI was associated with risk of DN in the crude model (OR 0.873, 95% CI 0.780 to 0.977, P=0.018) and adjusted model (OR 0.884, 95% CI 0.782 to 0.999, P=0.048). No association was found for baPWV. In conclusion, low ABI was associated with risk of CKD and DN in patients with type 2 diabetes.

Spectrum effect and spectrum bias in the oscillometric ankle brachial index to diagnose peripheral arterial disease: Clinical implications

BACKGROUND AND AIMS

The diagnostic performance of the oscillometric ankle brachial index (ABI) to detect peripheral arterial disease (PAD) varies among populations, suggesting a spectrum effect. When this heterogeneity modifies post-test probabilities, a spectrum bias arises. This study evaluates the presence and influence of spectrum effect and spectrum bias on test performance and clinical decisions.

METHODS

Oscillometric and Doppler ABI were compared in two settings: Primary-Care (333 legs) and Vascular-Service (41 legs). Spectrum effect was assessed using stratification and logistic regression, while spectrum bias was assessed through graphical and statistical tests based on predictive values and likelihood ratios, respectively.

RESULTS

Across subgroups, sensitivity ranged from 61.5% to 90.9%, and specificity from 81.8% to 99.1%. Logistic regression confirmed a spectrum effect in setting, diabetes, smoking status and age (univariate), and setting and diabetes (multivariate model). The positive likelihood ratio ranged from 5.0 to 89.1 in subgroups, leading to a spectrum bias in diabetic, smoking (both subgroups) and age (both subgroups). Therefore, a positive test ruled in differently the disease across subgroups, with a high rate of false positives in diabetic, smoking and >75-year-old patients. The negative likelihood ratio ranged from 0.09 to 0.39 in subgroups, with significant spectrum bias in Primary-Care patients, non-diabetics and smokers. Thus, in these subgroups, a negative test ruled out the disease with less certainty.

CONCLUSIONS

Spectrum effect and spectrum bias were found in oscillometric ABI to detect PAD, potentially affecting clinical decisions, especially for positive tests. Information about spectrum variables and the application of specific subgroups indicators are necessary.

The importance of accurate methodology in ABPI calculation when assessing lower limb wounds

Recent health economic publications have highlighted the cost of wound care and demonstrated the important role played by community and practice nurses in delivering care. Leg ulcers form a significant proportion of the wounds managed in the community. Data indicates that many patients are managed with no specific diagnosis or without calculation of the ankle brachial pressure index (ABPI), despite care guidelines emphasising the importance of a full assessment including Doppler ABPI calculation in patient management. This article highlights the important role Doppler ABPI plays in patient assessment and describes the methodology, focusing on the importance of correct application of the technique if reliable reproducible results are to be obtained. The rationale for obtaining blood pressure readings from both arms is discussed, and the possible error resulting from reliance on single upper limb blood pressure measurement for both manual and automated ABPI calculation is highlighted and its impact on ABPI calculation illustrated.

Accuracy and repeatability of the Dopplex Ability

BACKGROUND

Ankle-brachial index (ABI) and pulse volume recordings (PVR) are non-invasive tests used in diagnosis of peripheral arterial disease (PAD). The Dopplex Ability is an automated ABI/PVR device utilising air plethysmography, offering easy and rapid PAD diagnosis. The accuracy and repeatability of the Dopplex were assessed in comparison to the Doppler/air plethysmography-based Parks Flo-Lab system.

METHODS

Sixty-six patients (n = 129 lower limbs) were assessed with both Dopplex and Parks systems. For Dopplex ABI and PVR to be deemed accurate, it had to be within ±10% of the Parks ABI, and the PVR grade (1-4) had to be equal. The coefficient of variation (CV) was calculated from three repeat ABI/PVR readings to assess repeatability.

RESULTS

The Dopplex and Parks devices correlated poorly for ABI (R2 = 0.17) with only 43% of ABIs and 69% of PVRs meeting the accuracy criteria compared to the Parks values. The specificity and sensitivity were 56% and 82%, respectively for ABI, and 91% and 89%, respectively for PVRs. The Dopplex showed a significantly higher CV for both ABIs and PVRs compared to the Parks.

CONCLUSION

We found the Dopplex device to demonstrate suboptimal accuracy and repeatability in assessing ABI/PVR, and it was deemed unsuitable for use in our community.

Podiatry Ankle Duplex Scan: Readily Learned and Accurate in Diabetes

We aimed to train podiatrists to perform a focused duplex ultrasound scan (DUS) of the tibial vessels at the ankle in diabetic patients; podiatry ankle (PodAnk) duplex scan. Thirteen podiatrists underwent an intensive 3-hour long simulation training session. Participants were then assessed performing bilateral PodAnk duplex scans of 3 diabetic patients with peripheral arterial disease. Participants were assessed using the duplex ultrasound objective structured assessment of technical skills (DUOSATS) tool and an "Imaging Score". A total of 156 vessel assessments were performed. All patients had abnormal waveforms with a loss of triphasic flow. Loss of triphasic flow was accurately detected in 145 (92.9%) vessels; the correct waveform was identified in 139 (89.1%) cases. Participants achieved excellent DUOSATS scores (median 24 [interquartile range: 23-25], max attainable score of 26) as well as "Imaging Scores" (8 [8-8], max attainable score of 8) indicating proficiency in technical skills. The mean time taken for each bilateral ankle assessment was 20.4 minutes (standard deviation ±6.7). We have demonstrated that a focused DUS for the purpose of vascular assessment of the diabetic foot is readily learned using intensive simulation training.

Macrovascular Complications in Patients with Diabetes and Prediabetes

Diabetes is a significant health problem worldwide, and its association with cardiovascular disease (CVD) was reported in several studies. Hyperglycemia and insulin resistance seen in diabetes and prediabetes lead to an increase in reactive oxygen species, which triggers intracellular molecular signaling. The resulting prothrombotic state and increase in inflammatory mediators expedite atherosclerotic changes and the development of macrovascular complications. Individuals with diabetes or prediabetes have a higher risk of developing myocardial infarction, stroke, and peripheral artery disease. However, no significant difference in cardiovascular morbidity has been observed with tight glycemic control despite a reduction in some CVD outcomes, and the risk of adverse outcomes such as hypoglycemia was increased. Recently, some GLP-1 receptor agonists and SGLT-2 inhibitors have been shown to reduce cardiovascular events and mortality. In this review we give an overview of the risk and pathogenesis of cardiovascular disease among diabetic and prediabetic patients, as well as the implication of recent changes in diabetes management.

Different methods of calculating ankle-brachial index in mid-elderly men and women: the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

The ankle-brachial index (ABI) is a marker of subclinical atherosclerosis related to health-adverse outcomes. ABI is inexpensive compared to other indexes, such as coronary calcium score and determination of carotid artery intima-media thickness (IMT). Our objective was to identify how the ABI can be applied to primary care. Three different methods of calculating the ABI were compared among 13,921 men and women aged 35 to 74 years who were free of cardiovascular diseases and enrolled in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). The ABI ratio had the same denominator for the three categories created (the highest value for arm systolic blood pressure), and the numerator was based on the four readings for leg systolic blood pressure: the highest (ABI-HIGH), the mean (ABI-MEAN), and the lowest (ABI-LOW). The cut-off for analysis was ABI<1.0. All determinations of blood pressure were done with an oscillometric device. The prevalence of ABI<1% was 0.5, 0.9, and 2.7 for the categories HIGH, MEAN and LOW, respectively. All methods were associated with a high burden of cardiovascular risk factors. The association with IMT was stronger for ABI-HIGH than for the other categories. The proportion of participants with a 10-year Framingham Risk Score of coronary heart disease >20% without the inclusion of ABI<1.0 was 4.9%. For ABI-HIGH, ABI-MEAN and ABI-LOW, the increase in percentage points was 0.3, 0.7, and 2.3%, respectively, and the relative increment was 6.1, 14.3, and 46.9%. In conclusion, all methods were acceptable, but ABI-LOW was more suitable for prevention purposes.

The accuracy of an oscillometric ankle-brachial index in the diagnosis of lower limb peripheral arterial disease: A systematic review and meta-analysis

INTRODUCTION

Peripheral arterial disease (PAD) remains underdiagnosed and undertreated, partly because of limitations in the Doppler ankle-brachial index (ABI), the non-invasive gold standard.

OBJECTIVE

This systematic review and meta-analysis aims to compare the diagnostic accuracy of the oscillometric ABI and the Doppler ABI, and to examine the influence of two approaches to analysis: legs vs subjects and inclusion of oscillometric errors as PAD equivalents vs exclusion.

METHODS

Systematic searches in EMBASE, MEDLINE, Web of Science and the Cochrane Library databases were performed, from inception to February 2017. Random-effects models were computed with the Moses-Littenberg constant. Hierarchical summary receiver operating characteristic curves (HSROC) were used to summarise the overall test performance.

RESULTS

Twenty studies (1263 subjects and 3695 legs) were included in the meta-analysis. The pooled diagnostic odds ratio (dOR) for the oscillometric ABI was 32.49 (95% CI: 19.6-53.8), with 65% sensitivity (95% CI: 57-74) and 96% specificity (95%CI: 93-99). In the subgroup analysis, the "per subjects" group showed a better performance than the "per legs" group (dOR 36.44 vs 29.03). Similarly, an analysis considering oscillometric errors as PAD equivalents improved diagnostic performance (dOR 31.48 vs 28.29). The time needed for the oscillometric ABI was significantly shorter than that required for the Doppler ABI (5.90 vs 10.06 minutes, respectively).

CONCLUSIONS AND RELEVANCE

The oscillometric ABI showed an acceptable diagnostic accuracy and feasibility, potentially making it a useful tool for PAD diagnosis. We recommend considering oscillometric errors as PAD equivalents, and a "per subject" instead of a "per leg" approach, in order to improve sensitivity. Borderline oscillometric ABI values in diabetic population should raise concern of PAD.

The Validity and Reliability between Automated Oscillometric Measurement of Ankle-Brachial Index and Standard Measurement by Eco-Doppler in Diabetic Patients with or without Diabetic Foot

OBJECTIVE

To evaluate the concordance between oscillometric ABI and standard Doppler ABI in diabetic Chinese patients with or without diabetic foot.

METHODS

230 consecutive diabetic patients (n = 459 limbs) were included. The right and left ABIs were determined with both devices by the same investigator. The concordance and agreement were assessed by kappa index and the Bland-Altman method.

RESULTS

The average Doppler ABI was 1.003 ± 0.286 on the right and 0.990 ± 0.287 on the left, while oscillometric ABI was 1.002 ± 0.332 and 0.993 ± 0.319, which had no significance. The average time for oscillometric ABI was 8.600 versus 16.980 minutes for Doppler ABI (p < 0.001). There was good agreement between the two measurements, with a kappa value of 0.869 on the right and 0.919 on the left. Regarding the Doppler ABI as the gold standard, the accuracy, sensitivity, specificity, +LR, and -LR of oscillometric ABI reached 95.22%, 94.34%, 95.48%, 20.873%, and 0.059% on the right. For the left, it was 96.94%, 96.43%, 97.11%, 33.364%, and 0.036%.

CONCLUSIONS

The oscillometric measurement is a reliable, convenient, and less time-consuming alternative to standard Doppler ABI in patients. It should be widely used for PAD detection.

Diagnostic Accuracy Study of an Oscillometric Ankle-Brachial Index in Peripheral Arterial Disease: The Influence of Oscillometric Errors and Calcified Legs

BACKGROUND

Peripheral arterial disease (PAD) is an indicator of widespread atherosclerosis. However, most individuals with PAD, in spite of being at high cardiovascular risk, are asymptomatic. This fact, together with the limitations of the Doppler ankle-brachial index (ABI), contributes to PAD underdiagnose. The aim of this study was to compare oscillometric ABI and Doppler ABI to diagnose peripheral arterial disease, and also to examine the influence of oscillometric errors and calcified legs on the PAD diagnoses.

METHODS AND FINDINGS

We measured the ankle-brachial indexes of 90 volunteers (n = 180 legs, age 70 ± 14 years, 43% diabetics) using both oscillometer OMRON-M3 and Doppler. For concordance analyses we used the Bland and Altman method, and also estimated the intraclass correlation coefficient. Receiver Operating Characteristic Curves were used to examine the diagnostic performance of both methods. The ABI means were 1.06 ± 0.14 and 1.04 ± 0.16 (p = 0.034) measured by oscillometer and Doppler ABIs respectively, with limits of agreement of ± 0.20 and intraclass correlation coefficient = 0.769. Oscillometer yielded 23 "error" measurements, and also overestimated the measurements in low ankle pressures. Using Doppler as gold standard, oscillometer performance for diagnosis of PAD showed an Area Under Curve = 0.944 (sensitivity: 66.7%, specificity: 96.8%). Moreover, when considered calcified legs and oscillometric "error" readings as arteriopathy equivalents, sensitivity rose to 78.2%, maintaining specificity in 96%. The best oscillometer cut-off point was 0.96 (sensitivity: 87%, specificity: 91%, positive likelihood ratio: 9.66 and negative likelihood ratio: 0.14).

CONCLUSION

Despite its limitations, oscillometric ABI could be a useful tool for the diagnosis of PAD, particularly when considering calcified legs and oscillometric "errors" readings as peripheral arterial disease equivalents.

Exposure to secondhand smoke and risk of peripheral arterial disease in southern Chinese non-smokers: The Guangzhou Biobank Cohort Study-Cardiovascular Disease Sub-cohort

Objectives

We studied the association between secondhand smoke (SHS) exposure and peripheral arterial disease (PAD) in Chinese non-smokers.

Methods

We conducted a cross-sectional study using baseline data from the Guangzhou Biobank Cohort Study: Cardiovascular Disease Sub-cohort Study (GBCS-CVD). Guangzhou residents aged ≥ 50 years were recruited between 2003 and 2008. Baseline data included measurement of ankle brachial pressure index (ABPI) and self-reported smoking status and SHS exposure. Univariate and multivariate logistic regression analyses were used to analyze the association between SHS and PAD (defined as ABPI < 0.9).

Results

Of the 1507 non-smokers, 24 (1.6%) had PAD. Of these, 12 were men and 12 were women. Exposure to SHS at home of ≥25 h per week was reported by 16.7% of PAD cases compared with 3.8% of those without PAD (χ2 test, p = 0.003). After adjustment for potential confounders, exposure to ≥25 h per week at home was still associated with PAD (adjusted OR 7.86, 95% CI 2.00–30.95, p = 0.003), with suggestion of a dose-response relationship.

Conclusions

Our results extend the US Surgeon General’s 2006 report that SHS exposure is an independent risk factor for PAD. National smoke-free legislation is needed to protect all people from exposure.

Ankle brachial index for the diagnosis of lower limb peripheral arterial disease

BACKGROUND

Peripheral arterial disease (PAD) of the lower limb is common, with prevalence of both symptomatic and asymptomatic disease estimated at 13% in the over 50 age group. Symptomatic PAD affects about 5% of individuals in Western populations between the ages of 55 and 74 years. The most common initial symptom of PAD is muscle pain on exercise that is relieved by rest and is attributed to reduced lower limb blood flow due to atherosclerotic disease (intermittent claudication). The ankle brachial index (ABI) is widely used by a variety of healthcare professionals, including specialist nurses, physicians, surgeons and podiatrists working in primary and secondary care settings, to assess signs and symptoms of PAD. As the ABI test is non-invasive and inexpensive and is in widespread clinical use, a systematic review of its diagnostic accuracy in people presenting with leg pain suggestive of PAD is highly relevant to routine clinical practice.

OBJECTIVES

To estimate the diagnostic accuracy of the ankle brachial index (ABI) - also known as the ankle brachial pressure index (ABPI) - for the diagnosis of peripheral arterial disease in people who experience leg pain on walking that is alleviated by rest.

SEARCH METHODS

We carried out searches of the following databases in August 2013: MEDLINE (Ovid SP),Embase (Ovid SP), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (EBSCO), Latin American and Caribbean Health Sciences (LILACS) (Bireme), Database of Abstracts of Reviews of Effects and the Health Technology Assessment Database in The Cochrane Library, the Institute for Scientific Information (ISI) Conference Proceedings Citation Index - Science, the British Library Zetoc Conference search and Medion.

SELECTION CRITERIA

We included cross-sectional studies of ABI in which duplex ultrasonography or angiography was used as the reference standard. We also included cross-sectional or diagnostic test accuracy (DTA) cohort studies consisting of both prospective and retrospective studies.Participants were adults presenting with leg pain on walking that was relieved by rest, who were tested in primary care settings or secondary care settings (hospital outpatients only) and who did not have signs or symptoms of critical limb ischaemia (rest pain, ischaemic ulcers or gangrene).The index test was ABI, also called the ankle brachial pressure index (ABPI) or the Ankle Arm Index (AAI), which was performed with a hand-held doppler or oscillometry device to detect ankle vessels. We included data collected via sphygmomanometers (both manual and aneroid) and digital equipment.

DATA COLLECTION AND ANALYSIS

Two review authors independently replicated data extraction by using a standard form, which included an assessment of study quality, and resolved disagreements by discussion. Two review authors extracted participant-level data when available to populate 2×2 contingency tables (true positives, true negatives, false positives and false negatives).After a pilot phase involving two review authors working independently, we used the methodological quality assessment tool the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2), which incorporated our review question - along with a flow diagram to aid reviewers' understanding of the conduct of the study when necessary and an assessment of risk of bias and applicability judgements.

MAIN RESULTS

We screened 17,055 records identified through searches of databases. We obtained 746 full-text articles and assessed them for relevance. We scrutinised 49 studies to establish their eligibility for inclusion in the review and excluded 48, primarily because participants were not patients presenting solely with exertional leg pain, investigators used no reference standard or investigators used neither angiography nor duplex ultrasonography as the reference standard. We excluded most studies for more than one reason.Only one study met the eligibility criteria and provided limb-level accuracy data from just 85 participants (158 legs). This prospective study compared the manual doppler method of obtaining an ABI (performed by untrained personnel) with the automated oscillometric method. Limb-level data, as reported by the study, indicated that the accuracy of the ABI in detecting significant arterial disease on angiography is superior when stenosis is present in the femoropopliteal vessels, with sensitivity of 97% (95% confidence interval (CI) 93% to 99%) and specificity of 89% (95% CI 67% to 95%) for oscillometric ABI, and sensitivity of 95% (95% CI 89% to 97%) and specificity of 56% (95% CI 33% to 70%) for doppler ABI. The ABI threshold was not reported. Investigators attributed the lower specificity for doppler to the fact that a tibial or dorsalis pedis pulse could not be detected by doppler in 12 of 27 legs with normal vessels or non-significant lesions. The superiority of the oscillometric (automated) method for obtaining an ABI reading over the manual method with a doppler probe used by inexperienced operators may be a clinically important finding.

AUTHORS' CONCLUSIONS

Evidence about the accuracy of the ankle brachial index for the diagnosis of PAD in people with leg pain on exercise that is alleviated by rest is sparse. The single study included in our review provided only limb-level data from a few participants. Well-designed cross-sectional studies are required to evaluate the accuracy of ABI in patients presenting with early symptoms of peripheral arterial disease in all healthcare settings. Another systematic review of existing studies assessing the use of ABI in alternative patient groups, including asymptomatic, high-risk patients, is required.

Detection of peripheral arterial disease with an improved automated device: comparison of a new oscillometric device and the standard Doppler method

In occidental countries, peripheral arterial disease (PAD) is an important health issue; however, most subjects are asymptomatic (~50%) and therefore undiagnosed and untreated. Current guidelines recommend screening for PAD in primary care setting using ankle brachial index (ABI) in all patients with cardiovascular risks. This is, however, not performed strictly because the standard Doppler method is cumbersome and time-consuming. Here, we evaluate the accuracy and reproducibility of ABI measurements obtained by an improved automated oscillometric device, the MESI ABPI MD(®) device, and the standard Doppler method. ABI was measured in random order in a general practice with Doppler probes by two operators separately (ABI_dop) and twice with the MESI ABPI MD device (ABI_mesi). ABI_dop was calculated dividing the highest systolic blood pressure from both tibial and dorsalis pedis arteries by the highest systolic blood pressure of both brachial arteries. ABI_mesi was obtained automatically with simultaneous measurements on three extremities. According to ABI_dop, PAD was present in 10% of the 136 screened subjects (68.2±7.4 years). Interoperator coefficient of variation was 5.5% for ABI_dop, while the intrasubject coefficient of variation for ABI_mesi was 3.0%. ABI_mesi was correlated with ABI_dop (R=0.61, P<0.0001). The difference between the two techniques was 0.06±0.14 with ABI_mesi providing slightly higher values (P<0.0001) and negligible bias across the range (R=0.19, P<0.0001). Therefore, ABI_mesi ≤1 had a sensitivity of 85% and specificity of 96% to detect ABI_dop ≤0.9 and hence PAD. Doppler measurements took seven times longer than MESI ABPI MD measurements to be performed. In conclusion, MESI improved automated oscillometric method and offered a faster and repeatable measurement of ABI with only a small, clinically irrelevant overestimation of ABI value. The tested MESI ABPI MD-improved oscillometric system can be used as a screening tool for patients in general practice and would enable family doctors to comply with current guidelines for PAD.

Assessment of foot perfusion in patients with a diabetic foot ulcer

Assessment of foot perfusion is a vital step in the management of patients with diabetic foot ulceration, in order to understand the risk of amputation and likelihood of wound healing. Underlying peripheral artery disease is a common finding in patients with foot ulceration and is associated with poor outcomes. Assessment of foot perfusion should therefore focus on identifying the presence of peripheral artery disease and to subsequently estimate the effect this may have on wound healing. Assessment of perfusion can be difficult because of the often complex, diffuse and distal nature of peripheral artery disease in patients with diabetes, as well as poor collateralisation and heavy vascular calcification. Conventional methods of assessing tissue perfusion in the peripheral circulation may be unreliable in patients with diabetes, and it may therefore be difficult to determine the extent to which poor perfusion contributes to foot ulceration. Anatomical data obtained on cross-sectional imaging is important but must be combined with measurements of tissue perfusion (such as transcutaneous oxygen tension) in order to understand the global and regional perfusion deficit present in a patient with diabetic foot ulceration. Ankle-brachial pressure index is routinely used to screen for peripheral artery disease, but its use in patients with diabetes is limited in the presence of neuropathy and medial arterial calcification. Toe pressure index may be more useful because of the relative sparing of pedal arteries from medial calcification but may not always be possible in patients with ulceration. Fluorescence angiography is a non-invasive technique that can provide rapid quantitative information about regional tissue perfusion; capillaroscopy, iontophoresis and hyperspectral imaging may also be useful in assessing physiological perfusion but are not widely available. There may be a future role for specialized perfusion imaging of these patients, including magnetic resonance imaging techniques, single-photon emission computed tomography and PET-based molecular imaging; however, these novel techniques require further validation and are unlikely to become standard practice in the near future.

Effectiveness of bedside investigations to diagnose peripheral artery disease among people with diabetes mellitus: a systematic review

Non-invasive tests for the detection of peripheral artery disease (PAD) among individuals with diabetes mellitus are important to estimate the risk of amputation, ulceration, wound healing and the presence of cardiovascular disease, yet there are no consensus recommendations to support a particular diagnostic modality over another and to evaluate the performance of index non-invasive diagnostic tests against reference standard imaging techniques (magnetic resonance angiography, computed tomography angiography, digital subtraction angiography and colour duplex ultrasound) for the detection of PAD among patients with diabetes. Two reviewers independently screened potential studies for inclusion and extracted study data. Eligible studies evaluated an index test for PAD against a reference test. An assessment of methodological quality was performed using the quality assessment for diagnostic accuracy studies instrument. Of the 6629 studies identified, ten met the criteria for inclusion. In these studies, the patients had a median age of 60-74 years and a median duration of diabetes of 9-24 years. Two studies reported exclusively on patients with symptomatic (ulcerated/infected) feet, two on patients with asymptomatic (intact) feet only, and the remaining six on patients both with and without foot ulceration. Ankle brachial index (ABI) was the most widely assessed index test. Overall, the positive likelihood ratio and negative likelihood ratio (NLR) of an ABI threshold <0.9 ranged from 2 to 25 (median 8) and <0.1 to 0.7 (median 0.3), respectively. In patients with neuropathy, the NLR of the ABI was generally higher (two out of three studies), indicating poorer performance, and ranged between 0.3 and 0.5. A toe brachial index <0.75 was associated with a median positive likelihood ratio and NLRs of 3 and ≤ 0.1, respectively, and was less affected by neuropathy in one study. Also, in two separate studies, pulse oximetry used to measure the oxygen saturation of peripheral blood and Doppler wave form analyses had NLRs of 0.2 and <0.1. The reported performance of ABI for the diagnosis of PAD in patients with diabetes mellitus is variable and is adversely affected by the presence of neuropathy. Limited evidence suggests that toe brachial index, pulse oximetry and wave form analysis may be superior to ABI for diagnosing PAD in patients with neuropathy with and without foot ulcers. There were insufficient data to support the adoption of one particular diagnostic modality over another and no comparisons existed with clinical examination. The quality of studies evaluating diagnostic techniques for the detection of PAD in individuals with diabetes is poor. Improved compliance with guidelines for methodological quality is needed in future studies.

Borderline ankle-brachial index is associated with increased prevalence of micro- and macrovascular complications in type 2 diabetes: A cross-sectional analysis of 12,772 patients from the Joint Asia Diabetes Evaluation Program

Borderline ankle-brachial index is increasingly recognised as a marker of cardiovascular risk. We evaluated the impact of borderline ankle-brachial index in 12,772 Chinese type 2 diabetes patients from the Joint Asia Diabetes Evaluation Program between 2007 and 2012. Cardiovascular risk factors, complications and health-related quality of life were compared between patients with normal ankle-brachial index (1.0-1.4), borderline ankle-brachial index (0.90-0.99) and peripheral arterial disease (ankle-brachial index < 0.9). The prevalence of peripheral arterial disease and borderline ankle-brachial index was 4.6% and 9.6%, respectively. Borderline ankle-brachial index patients were older, more likely to be smokers and hypertensive, had longer duration of diabetes, poorer kidney function and poorer health-related quality of life than patients with normal ankle-brachial index. After adjustment for traditional cardiovascular risk factors, borderline ankle-brachial index was an independent predictor of diabetes-related micro- and macrovascular complications including retinopathy (odd ratios: 1.19 (95% confidence interval: 1.04-1.37)), macroalbuminuria (1.31 (1.10-1.56)), chronic kidney disease (1.22 (1.00-1.50)) and stroke (1.31 (1.05-1.64)). These findings suggest that patients with diabetes and borderline ankle-brachial index are at increased cardiovascular risk and may benefit from more intensive management.

What Is the Clinical Utility of the Ankle-Brachial Index in Patients With Diabetic Foot Ulcers and Radiographic Arterial Calcification?

The purpose of this study was to analyze the influence of radiographic arterial calcification (RAC) on the clinical interpretation of ankle-brachial index (ABI) values in patients with diabetic foot ulcers. We analyzed a retrospective clinical database of 60 patients with diabetic foot ulcers from the Diabetic Foot Unit (Complutense University, Madrid, Spain) between January 2012 and March 2014. For each patient, anteroposterior XR-plains were evaluated, and the ABI and toe-brachial index (TBI) were assessed by an experienced clinician. To analyze the correlation among quantitative variables, we applied the Pearson correlation coefficient. Fifty percent (n = 9/18) of our patients with a normal ABI and RAC had a TBI < 0.7 associated with peripheral arterial disease (PAD). In patients with RAC, the prevalence of a normal ABI (72%, 18/25) was higher than in patients without RAC (52%, 11/21). The Pearson correlation coefficient among the ABI and TBI in patients with an ABI < 1.4 (n = 46) was lesser (r = .484, P = .001) than in patients with an ABI < 1.4 but without RAC (n = 21; r = .686, P = .001). ABI values between 0.9 and 1.4 would be falsely considered as normal and could underestimate the prevalence of PAD, especially in patients with neuropathy, diabetic foot ulcers, or RAC.