Association of Abnormal Lung Function and Its Subtypes With Arterial Stiffness: A Longitudinal Cohort Study.

BACKGROUND: Prior studies have reported the cross-sectional relationship between lung function and arterial stiffness, while the longitudinal association remains unclear to date. This study aimed to investigate whether abnormal lung function and its subtypes at baseline are associated with increased arterial stiffness using a cohort. METHODS AND RESULTS: This was a secondary analysis extracting 2461 participants from Beijing Health Management Cohort as baseline and annually followed for development of arterial stiffness. Abnormal lung function was defined by forced expiratory volume in 1s <80% of the predicted value, forced vital capacity of the predicted value, or forced expiratory volume in 1s/forced vital capacity ratio <70%. Increased arterial stiffness was determined by brachial-ankle pulse wave velocity ≥1400 cm/s. Cox proportional hazards model was used to calculate the hazard ratio and population attributable fraction. The mean age was 42.8±8.1 years, and 444 (18.0%) cases developed increased arterial stiffness during a median follow-up of 3.0 years. The adjusted hazard ratio (95% CI) of arterial stiffness was 1.47 (95% CI, 1.10-1.96) for abnormal lung function, with a population attributable fraction of 3.9% (95% CI, 0.8-7.1). Of subtypes, only obstructive ventilatory dysfunction was significantly associated with arterial stiffness (adjusted hazard ratio, 2.06 [95% CI, 1.27-3.36]), not restricted ventilatory dysfunction (adjusted hazard ratio, 0.95 [95% CI, 0.54-1.65]). Consistent results were observed on multiple sensitivity analyses. CONCLUSIONS: Our study indicated a longitudinal association of abnormal lung function with increased arterial stiffness using a large cohort, especially for the obstructive ventilatory dysfunction.

Arterial Stiffness Is Associated With Small Vessel Disease Irrespective of Blood Pressure in Stroke-Free Individuals.

BACKGROUND: Arterial stiffness and hypertension are important risk factors for cerebral small vessel disease (CSVD). Clinically, there are hypertensive patients with low pulse wave velocity (PWV) and nonhypertensive individuals with high PWV. We aimed to determine the effects of arterial stiffness on CSVD in normotensive individuals. METHODS: An observational cross-sectional study was conducted in 1894 stroke-free participants who underwent brain magnetic resonance imaging and brachial-ankle pulse wave velocity (baPWV) measurements at a health checkup between 2013 and 2020. CSVD was defined as any of following: white matter hyperintensities, cerebral microbleeds, silent lacunar infarcts, and enlarged perivascular spaces. baPWV was measured using an automatic oscillometric device. Participants were divided into 4 groups according to the following cutoff points: low blood pressure (BP, <120/80 mm Hg) with low baPWV (<14.63 m/s, a cutoff value that predicted CSVD); high BP (≥120/80 mm Hg) with low baPWV; low BP with high baPWV (≥14.63 m/s); and high BP with high baPWV. RESULTS: The mean age of the participants was 57±13 years (41% women). The prevalence of CSVD was 718 (38%), which was higher in the low BP with high baPWV (56%) and high BP with high baPWV (55%) groups than in the high BP with low baPWV (24%) and low BP with low baPWV (22%) groups. Compared with the low BP with low baPWV group, the low BP with high baPWV group (odds ratio, 1.63 [95% CI, 1.09-2.43]) and the high BP with high baPWV group (odds ratio, 1.86 [95% CI, 1.39-2.49]) had a significantly higher multivariable-adjusted risk for CSVD. CONCLUSIONS: Individuals with a high baPWV had a higher prevalence of CSVD, independent of BP status. Higher arterial stiffness is likely to be a more important risk factor for CSVD than BP status in stroke-free individuals.

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.

Importance of anemia in heart failure over blood pressure variability.

BACKGROUND: The evaluation of arteriosclerosis (vascular function) is important when treating heart failure (HF). Vascular dysfunction is associated with anemia through renal function and endothelial nitric oxide synthase. Additionally, blood pressure (BP) variability (BPV) caused by vascular dysfunction is also associated with HF prognosis. However, how anemia and BPV may affect HF prognosis is unclear. METHODS: Between January 2012 and July 2018, 214 patients with HF were hospitalized. The cardio-ankle vascular index (CAVI) as an index of arteriosclerosis of these patients was measured. The patients were divided into the elevated and preserved CAVI groups. We investigated the factors related to major adverse cardiovascular events (MACEs) as cardiovascular death or rehospitalization within 1 year after discharge. RESULTS: In the elevated CAVI group, significant differences in body mass index (BMI), BPV, left ventricular dimension, and hemoglobin levels were observed between patients with and without MACEs. In the preserved CAVI group, significant differences in BMI, diastolic/mean BP, and hemoglobin levels were observed between those with and without MACEs. The multivariate analysis showed an independent association between hemoglobin levels and MACE occurrence in both the elevated and preserved CAVI groups (elevated CAVI group: hazard ratio [HR] = 0.800, p = .045 [model 1], HR = 0.802, p = .035 [model 2]; preserved CAVI group: HR = 0.783, p = .049 [model 1], HR = 0.752, p = .023 [model 2], and HR = 0.754, p = .024 [model 3]). CONCLUSIONS: Anemia was independently associated with HF prognosis with or without arteriosclerosis.

Assessing Automatic Plethysmographic Ankle-Brachial Index Devices in Peripheral Artery Disease Detection: A Comparative Study with Doppler Ankle-Brachial Index Measurements.

BACKGROUND The ankle-brachial index (ABI) is a critical diagnostic test for peripheral artery disease (PAD), albeit requiring technical expertise and dedicated resources. The advent of automatic ABI devices proposes a more accessible approach, necessitating fewer resources and less expertise. This study was conducted to gather data on PAD prevalence and to evaluate the correlation and efficacy of automatic ABI measurements vs traditional Doppler ABI measurements to understand their potential role in primary care settings. MATERIAL AND METHODS ABI measurements were obtained using both the Doppler method and an automatic plethysmographic device (Dopplex ABility, Huntleigh Healthcare). RESULTS Of the 290 participants (mean age 67.6±7.4 years), Doppler ABI method identified 16.8% with abnormal results (<0.9), while the automatic method identified only 5.9%. The mean Doppler ABI was 1.05±0.15, and the mean automatic ABI was 1.12±0.13. The sensitivity of the automatic ABI measurements was 22.2%, and the specificity was 96.8%, with a positive predictive value of 57.1%, and a negative predictive value of 86.9%. Adjustments in the automatic assessment and inclusion of pulse wave velocity enhanced the diagnostic capabilities of the automatic ABI device. CONCLUSIONS While the automatic plethysmographic ABI device may lack the necessary diagnostic capabilities to replace the traditional Doppler ABI device as a standalone test in PAD diagnosis, it could still offer significant value in primary care settings if integrated with adjusted cut-off points and pulse wave velocity analysis.

Contrast-free ultrasound imaging for blood flow assessment of the lower limb in patients with peripheral arterial disease: a feasibility study.

While being a relatively prevalent condition particularly among aging patients, peripheral arterial disease (PAD) of lower extremities commonly goes undetected or misdiagnosed due to its symptoms being nonspecific. Additionally, progression of PAD in the absence of timely intervention can lead to dire consequences. Therefore, development of non-invasive and affordable diagnostic approaches can be highly beneficial in detection and treatment planning for PAD patients. In this study, we present a contrast-free ultrasound-based quantitative blood flow imaging technique for PAD diagnosis. The method involves monitoring the variations of blood flow in the calf muscle in response to thigh-pressure-cuff-induced occlusion. Four quantitative metrics are introduced for analysis of these variations. These metrics include post-occlusion to baseline flow intensity variation (PBFIV), total response region (TRR), Lag0 response region (L0RR), and Lag4 (and more) response region (L4 + RR). We examine the feasibility of this method through an in vivo study consisting of 14 PAD patients with abnormal ankle-brachial index (ABI) and 8 healthy volunteers. Ultrasound data acquired from 13 legs in the patient group and 13 legs in the healthy group are analyzed. Out of the four utilized metrics, three exhibited significantly different distributions between the two groups (p-value < 0.05). More specifically, p-values of 0.0015 for PBFIV, 0.0183 for TRR, and 0.0048 for L0RR were obtained. The results of this feasibility study indicate the diagnostic potential of the proposed method for the detection of PAD.

Performance of systolic pressure index for lower limb peripheral arterial disease in a group of elderly in sub-Saharan Africa.

BACKGROUND: The automatic measurement of the ankle-brachial index (ABI) constitutes a reliable, simple, safe, rapid, and inexpensive alternative diagnostic screening test compared with the Doppler method for peripheral arterial disease (PAD). We aimed to compare the diagnostic performance of automatic ABI measurement tests to Doppler ultrasound for PAD in a group of patients aged 65 years and above, in Sub-Saharan Africa. METHODS: This was an experimental comparative study of the performance of Doppler ultrasound to the automated ABI test in the diagnosis of PAD in patients aged ≥ 65 years followed-up at the Yaoundé Central Hospital, Cameroon between January to June 2018. An ABI threshold < 0.90 is defined as a PAD. We compare the sensitivity, and specificity of the high ankle-brachial index (ABI-HIGH), low ankle-brachial index (ABI-LOW), and the mean ankle-brachial index (ABI-MEAN) for both tests. RESULTS: We included 137 subjects with an average age of 71.7 ± 6.8 years. In the ABI-HIGH mode, the automatic device had a sensitivity of 55% and a specificity of 98.35% with a difference between the two techniques of d = 0.024 (p = 0.016). In the ABI-MEAN mode, it had a sensitivity of 40.63% and a specificity of 99.15%; d = 0.071 (p < 0.0001). In the ABI-LOW mode, it had a sensitivity of 30.95% and a specificity of 99.11%; d = 0.119 (p < 0.0001). CONCLUSION: The Automatic measurement of systolic pressure index has a better diagnostic performance in the detection of Peripheral Arterial Disease compared to the reference method by continuous Doppler in sub-Saharan African subjects aged ≥ 65 years.

Prevalence and predictors of lower extremity atherosclerotic disease amongst high-risk patients using ankle brachial index.

INTRODUCTION: The prevalence of lower extremity artery disease (LEAD) continues to increase worldwide. This is expected to translate into logarithmic rise in lower-limb amputations especially in the developing world. Majority of patients suffering from LEAD remain asymptomatic until late and are vulnerable to limb-threatening complications unless actively screened and treated. METHODS: This was a prospective, single-center, observational study to determine the prevalence and predictors of LEAD. Patients with known atherosclerotic vascular disease (but not known LEAD) or those at risk were enrolled. All underwent ankle brachial index (ABI) measurement as per the standard protocol. A threshold of ABI ≤0.90 was taken to diagnose LEAD. RESULTS: A total of 1000 patients were enrolled. The mean age of the group was 61.4 ± 10.0 years and the prevalence of LEAD was 10.2%. Amongst those who had LEAD, the majority of patients (69.6%) had no symptoms. The prevalence of LEAD in diabetic population in our study was 13.2% and it was 30.9% in coronary artery disease patients . Factors independently linked to LEAD on regression analysis included advanced age, presence of diabetes, smoking history, lower serum HDL and a lower ejection fraction. CONCLUSIONS: The vast majority of patients suffering from LEAD are asymptomatic. Early diagnoses and institution of appropriate medical and physical therapy can prevent excess morbidity and mortality due to LEAD. Factors independently linked to LEAD are advanced age, presence of diabetes, smoking history, lower serum HDL and a lower ejection fraction. The presence of either of these should signal undertaking of appropriate steps to unmask underlying LEAD.

Association between length of daily siesta and brachial-ankle pulse wave velocity (baPWV): a community-based cross sectional study in North China.

INTRODUCTION: To date, many studies have shown a link between siesta and cardiovascular events. Little is known regarding the connection between siesta and brachial-ankle pulse wave velocity (baPWV) levels, even though baPWV can determine the degree of atherosclerosis and vascular stiffness. Thus, we examined the relationship between siesta time and baPWV in a cross-sectional study. METHODS: Interviews, physical examinations, lab testing, and electron beam computed tomography were all part of the baseline evaluation for participants aged older than 35. Baseline data were compared for 3 different siesta habits: irregular or no siestas, daily short siestas (1 h or less), and daily long siestas (> 1 h). Utilizing logistic regression models and multivariate linear regression, the link between siesta time and baPWV was determined. RESULTS: Among all 6566 participants, the different siesta groups had a significant difference of the degrees of AS (P < 0.001). The same outcome was true for both males (P < 0.001) and females (P < 0.001). Numerous cardiovascular risk variables and markers of subclinical atherosclerosis were positively correlated with daily extended siestas. Results from the fully adjusted model showed that long siestas (> 60 min, OR = 1.18, 95%CI: 1.06-1.31, P = 0.002) were linked to a more severe level of the baPWV. For age or gender stratification, we found significant differences between non-siesta and > 60 min siesta groups. Multiple linear regression analysis revealed a positive connection between siesta duration and baPWV (ß = 0.197, P = 0.038). CONCLUSIONS: An elevated risk of atherosclerosis was shown to accompany prolonged siestas. These results need to be followed up on with prospective studies and additional lab work.

Ankle Brachial Index is a strong predictor of mortality in hypertensive patients: results of a five-year follow-up study.

BACKGROUND: In the hypertensive population, the peripheral arterial disease (PAD) is considered one of the target organ damages. Ankle Brachial Index (ABI) measurement represents the widely accepted clinical method that may objectively detect the presence of PAD. The study aimed to assess how PAD revealed by ABI predicts mortality in patients with hypertension. METHODS: In the follow-up time (5 years period) of the Hungarian ERV Study, a large scale, multicenter observational study, recruiting hypertensive subjects between 50-75 years, the association of PAD with the survival time was analysed. Several multivariate, interval-censored survival models were developed to assess this association. RESULTS: Among the 21892 enrolled hypertensive patients, the prevalence of PAD (ABI≤0.9) was 14.4%. The crude death rate was 5.44% (1190 cases) over the available observational period. In multivariate models male sex, myocardial infarction in patients' history, diabetes, renal failure, PAD and cardiovascular risk (SCORE risk) were significantly associated with mortality. Lower ABI showed a continuous, close to linear association with worse survival. PAD was predictive for mortality risk in all SCORE patient groups. CONCLUSIONS: Low ABI is a strong predictor of mortality in hypertensive patients between the age 50-75, even after adjustment for several potential confounders. The association is linear, with no apparent cut-off, suggesting that ABI should be handled as a continuous variable. The detection of PAD in hypertensives may contribute to the determination of total cardiovascular risk in hypertensive population.

Association of physical activity with vascular aging in a population with intermediate cardiovascular risk, analysis by sex: MARK study.

BACKGROUND: The aim of this study was to analyze the association of physical activity and its intensity with arterial stiffness and vascular aging and differences by sex in a Spanish population with intermediate cardiovascular risk. METHODS: Cross-sectional study. A total of 2475 individuals aged 35-75 years participated in the study. Brachial-ankle pulse wave velocity (baPWV) was measured using a VaSera VS-1500® device. Based on the age and sex percentile presented by the participants, the latter were classified as follows: those with a percentile above 90 and presenting established cardiovascular disease were classified as early vascular aging (EVA); those with a percentile between 10 and 90 were classified as normal vascular aging (NVA) and those with a percentile below 10 were classified as healthy vascular aging (HVA). Physical activity was analyzed through the short version of the Minnesota Leisure Time Physical Activity Questionnaire (MLTPAQ). RESULTS: The mean age of the participants was 61.34 ± 7.70 years, with 61.60% men. Of the total sample, 86% were sedentary (83% men vs 90% women). The total physical activity showed a negative association with baPWV (ß = - 0.045; 95% CI - 0.080 to - 0.009). Intense physical activity showed a negative relationship with baPWV (ß = - 0.084; 95% CI - 0.136 to - 0.032). The OR of the total physical activity and the intense physical activity carried out by the subjects classified as NVA with respect to those classified as HVA was OR = 0.946; (95% CI 0.898 to 0.997) and OR = 0.903; (95% CI 0.840 to 0.971), and of those classified as EVA it was OR = 0.916; (95% CI 0.852 to 0.986) and OR = 0.905; (95% CI 0.818 to 1.000). No association was found with moderate- or low-intensity physical activity. CONCLUSIONS: The results of this study suggest that, when intense physical activity is performed, the probability of presenting vascular aging is lower. In the analysis by sex, this association is only observed in men.

Association of Increased Pulse Wave Velocity With Long-Term Clinical Outcomes in Patients With Preserved Ankle-Brachial Index After Acute Myocardial Infarction.

BACKGROUND: Low ankle-brachial index (ABI) is an established risk factor for long-term cardiovascular outcomes in patients with acute myocardial infarction (AMI), and brachial-ankle pulse wave velocity (ba-PWV) may also be a risk factor. However, there is a significant overlap between low ABI and high ba-PWV. The purpose of this retrospective study was to examine whether increased ba-PWV was associated with long-term clinical outcomes in AMI patients with normal ABI. METHODS: We included 932 AMI patients with normal ABI and divided them into the high PWV group (≥1,400 cm/s; n=646) and the low PWV group (<1400 cm/s; n=286) according to the ba-PWV values measured during the AMI hospitalisation. The primary endpoint was the major adverse cardiovascular events (MACE) defined as the composite of all-cause death, nonfatal myocardial infarction, and hospitalisation for heart failure. RESULTS: During the median follow-up duration of 541 days (Q1: 215 days-Q3: 1,022 days), a total of 154 MACE were observed. The Kaplan-Meier curves showed that MACE was more frequently observed in the high PWV group than in the low PWV group (p<0.001). The multivariate Cox hazard analysis revealed that high ba-PWV was significantly associated with MACE (hazard ratio [HR] 1.587; 95% CI 1.002-2.513; p=0.049) after controlling multiple confounding factors. CONCLUSIONS: High ba-PWV was significantly associated with long-term adverse events in AMI patients with normal ABI. Our results suggest the usefulness of PWV as a prognostic marker in AMI with normal ABI.

Association of Arterial Stiffness with Functional Disability and Mobility Limitation: The Rugao Longitudinal Ageing Study.

OBJECTIVES: Arterial stiffness is a common issue that may represent an indicator of vascular ageing. We aimed to investigate the association of arterial stiffness with the risk of functional disability and mobility limitation in older adults. DESIGN: Prospective cohort study. SETTING AND PARTICIPANTS: A total of 1699 older adults from the Rugao Longitudinal Ageing Study were included and analysed. MEASUREMENTS: Arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV). Functional disability and mobility limitation were evaluated by the activities of daily living and the Timed Up and Go test, respectively. The associations of baPWV and risk of functional disability and mobility limitation were analysed using logistic regression models. Restricted cubic spline regressions were applied to estimate the possible nonlinear relationships between them. RESULTS: During the 3.5-year follow-up, 97 (10.00%) and 285 (31.11%) individuals were defined as new-onset functional disability and mobility limitation, respectively. After adjusting for confounding factors, elevated baPWV was significantly associated with a higher risk of incident functional disability (odds ratio [OR] 1.18, 95% confidence interval [CI] 1.06-1.31) and mobility limitation (OR 1.08, 95% CI 1.01-1.16). Additionally, consistent results were obtained from the stratified analyses of the different subgroups. Multivariable restricted cubic spline regression analysis further demonstrated that a near-linear association occurred between baPWV and the risk of incident functional disability and mobility limitation (P-overall < 0.01, P-nonlinear >0.05). CONCLUSION: Arterial stiffness, as assessed by baPWV, was associated with the risk of functional disability and mobility limitation in this community-based cohort, and these associations were nearly linear.

Fiabilidad de los métodos automatizados en la determinación del índice tobillo-brazo. Revisión sistemática / Reliability of automated methods in determining the ankle-brachial index. Systematic review

La enfermedad arterial periférica es uno de los principales factores que intervienen en la aparición de la úlcera de etiología isquémica de la extremidad inferior en mayores de 70 años. La aparición de esta patología conlleva un aumento de la mobimortalidad e, incluso, llega a afectar a la calidad de vida de la persona que la padece. Todo esto hace que sea necesario aplicar métodos diagnósticos que permitan establecer un diagnóstico temprano. Para ello, se lleva a cabo una exploración clínica inicial y una exploración hemodinámica mediante el cálculo del índice tobillo-brazo. El método que se considera como el gold standard es la técnica Doppler, sin embargo, el tiempo que conlleva su realización y la necesidad de un entrenamiento previo ha dificultado su práctica en atención primaria. Como solución a esto, se ha propuesto la sustitución del método tradicional por equipos oscilométricos automáticos. Para poder determinar la fiabilidad de los dispositivos automáticos en la determinación del índice tobillo-brazo se ha realizado una revisión sistemática de la literatura científica en las bases de datos: MEDLINE, SciELO, Cochrane, Elsevier y CUIDEN hasta febrero de 2020. Se obtuvo un total de 58 artículos, de los cuales se incluyeron 15 en el análisis. Los resultados publicados son varios debido a las diferentes metodologías empleadas, los perfiles de los pacientes seleccionados para el estudio y los diversos modelos de oscilometría estudiados en cada artículo. Por tanto, las diferencias encontradas en los artículos dificultan la realización de una comparación válida entre ellos, para poder determinar qué dispositivo automático sería el más fiable en el cálculo del índice tobillo-brazo en comparación con la técnica Doppler; y se recomienda que se continúen realizando investigaciones con un diseño más centrado que permita determinar una alternativa eficaz al método tradicional en la práctica clínica (AU)

Peripheral artery disease is one of the main factors involved in the onset of ischemic etiology ulcers of the lower limb in patients older than 70 years old. The appearance of this disease leads to an increase in the morbidity and mortality and even affects the quality of life of the person who suffers from this disease. All this makes it necessary to apply diagnostic methods to make an early diagnosis. To this end, an initial clinical examination and a hemodynamic examination are carried out by calculating the ankle-brachial index (ABI). The method that is considered the gold standard is the Doppler technique. However, the time involved in its implementation and the need for prior training has hampered its practice in primary care. As a solution to this, automatic oscillometric devices that measure blood pressure have been proposed to replace the traditional method. In order to determine the reliability of automatic devices when it comes to determining the ankle-brachial index, a systematic review of scientific literature databases has been performed: MEDLINE, SciELO, Cochrane, Elsevier and CUIDEN until February 2020. A total of 58 items were received, 15 of which were included for the analysis. Several published results are due to the different methodologies employed, profiles of patients selected for the study and various models of oscillometry studied in each article. Therefore, the differences found in the articles make it difficult to make a fair comparison between them in order to determine which device would be the most reliable in determining the ankle-brachial index compared to the Doppler technique; recommending the continuous designfocused research in order to establish an effective alternative to the traditional method in clinical practice (AU)

Impact of Ankle Brachial Index Calculations on Peripheral Arterial Disease Prevalence and as a Predictor of Cardiovascular Risk.

OBJECTIVE: The aim of this study was to estimate the prevalence and predictive accuracy for cardiovascular (CV) morbidity by using different ankle brachial index (ABI) calculation methods in the general population. METHODS: ABI measurements and questionnaire data were collected from 5 080 randomly selected citizens aged 60 - 90 years. A 10 year follow up with data from Swedish national health registries was carried out. ABI was calculated using as numerator the highest (ABI-HI) or the lowest (ABI-LO) ankle BP obtained in each leg. Subjects were defined as references or having peripheral arterial disease (PAD) based on ABI-LO (Group 1) or ABI-HI (Group 2). Prevalence, mortality, CV events and risk were then analysed for these three groups, and their predictive power by using the area under the curve (AUC). RESULTS: A total of 4 909 inhabitants were included in the cohort (References: 83.8%, Group 1: 6.7% and Group 2: 9.6%). The prevalence of PAD was 16% using ABI-LO, and 9.6% using ABI-HI. The 10 year all cause mortality for references and Groups 1 and 2 was 27.6%, 48.8%, and 67.2%, respectively. The overall age adjusted hazard ratio (95% confidence interval) for the composite outcome of CV mortality and a non-fatal CV event was 1.25 (1.06 - 1.49) for Group 1 and 2.11 (1.85 - 2.39) for Group 2. The prediction accuracy for ABI < 0.9 in predicting CV event measured with AUC was 0.60 for ABI-HI and 0.62 for ABI-LO. CONCLUSION: An ABI < 0.9 should be considered a strong risk marker for future CV morbidity. Applying the traditional ABI calculation method of using the highest measured ankle BP, a group of subjects with high CV risk may be overlooked for intervention, and this why the lowest ankle BP should be the preferred for risk stratification. However, as a single predictive tool an ABI < 0.9 cannot adequately discriminate which individual will have a future CV event regardless of calculation method used.

Artificial intelligence for the evaluation of peripheral artery disease using arterial Doppler waveforms to predict abnormal ankle-brachial index.

BACKGROUND: Patients with peripheral artery disease (PAD) are at increased risk for major adverse limb and cardiac events including mortality. Developing screening tools capable of accurate PAD identification is a necessary first step for strategies of adverse outcome prevention. This study aimed to determine whether machine analysis of a resting Doppler waveform using deep neural networks can accurately identify patients with PAD. METHODS: Consecutive patients (4/8/2015 - 12/31/2020) undergoing rest and postexercise ankle-brachial index (ABI) testing were included. Patients were randomly allocated to training, validation, and testing subsets (70%/15%/15%). Deep neural networks were trained on resting posterior tibial arterial Doppler waveforms to predict normal (> 0.9) or PAD (⩽ 0.9) using rest and postexercise ABI. A separate dataset of 151 patients who underwent testing during a period after the model had been created and validated (1/1/2021 - 3/31/2021) was used for secondary validation. Area under the receiver operating characteristic curves (AUC) were constructed to evaluate test performance. RESULTS: Among 11,748 total patients, 3432 patients met study criteria: 1941 with PAD (mean age 69 ± 12 years) and 1491 without PAD (64 ± 14 years). The predictive model with highest performance identified PAD with an AUC 0.94 (CI = 0.92-0.96), sensitivity 0.83, specificity 0.88, accuracy 0.85, and positive predictive value (PPV) 0.90. Results were similar for the validation dataset: AUC 0.94 (CI = 0.91-0.98), sensitivity 0.91, specificity 0.85, accuracy 0.89, and PPV 0.89 (postexercise ABI comparison). CONCLUSION: An artificial intelligence-enabled analysis of a resting Doppler arterial waveform permits identification of PAD at a clinically relevant performance level.

Diagnostic thresholds for absolute systolic toe pressure and toe-brachial index in diabetic foot screening.

INTRODUCTION: Identifying peripheral arterial disease (PAD) during diabetic foot screening (DFS) is crucial in reducing the risk of diabetic foot ulcerations and lower limb amputations. Screening assessments commonly used include absolute systolic toe pressure (ASTP) and toe-brachial index (TBI). There is a lack of research defining the threshold values of both assessment methods. We aimed to compare the accuracy of ASTP and TBI and establish optimal threshold values of ASTP and TBI with reference to the internationally accepted ankle-brachial pressure index (ABPI) screening test, for a multiethnic diabetic population in Singapore. METHODS: A retrospective, observational study of DFS results from January 2017 to December 2017 was conducted. Receiver operating characteristic analysis was conducted for ASTP and TBI using the internationally accepted ABPI cut-off value of ≤0.9 to indicate PAD. RESULTS: A total of 1,454 patients with mean (standard deviation) age of 63.1 (12.4) years old were included. There were 50.8% men and 49.2% women, comprising 69.7% Chinese, 13.5% Indian, 10.1% Malay and 6.7% other ethnicities. Areas under the curve for ASTP and TBI were 0.89 (95% confidence interval [Cl] 0.85-0.94) and 0.94 (95% Cl 0.90-0.98), respectively, and the difference was statistically significant (P<0.001). Derived optimal threshold values to indicate ABPI≤0.9 for ASTP and TBI were <95.5mmHg (specificity 0.86, sensitivity 0.84) and <0.7 (specificity 0.89, sensitivity 0.95), respectively. CONCLUSION: ASTP or TBI may be used to detect ABPI-determined PAD in DFS. The optimal threshold values derived from a multiethnic Asian diabetic population were <95.5mmHg for ASTP and <0.7 for TBI.

Diagnostic Accuracy of Ankle-Brachial Pressure Index Compared with Doppler Arterial Waveforms for Detecting Peripheral Arterial Disease: A Systematic Review.

GENERAL PURPOSE: To present the results of a research study evaluating the diagnostic accuracy of the ankle-brachial pressure index (ABPI) compared with that of Doppler arterial waveforms (DAWs) to detect peripheral arterial disease (PAD). TARGET AUDIENCE: This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care. LEARNING OBJECTIVES/OUTCOMES: After completing this continuing education activity, the participant will:1. Summarize the evidence the authors considered when comparing the diagnostic accuracy of the ABPI with that of Doppler arterial waveforms to detect PAD.2. Select the characteristics of the participants in the studies the authors analyzed.3. Identify the results of the authors' study comparing the diagnostic accuracy of the ABPI with that of Doppler arterial waveforms to detect PAD.4. Distinguish the authors' conclusions about the advantages of using Doppler arterial waveforms to detect PAD.

Although the ankle-brachial pressure index (ABPI) is a useful tool for the noninvasive assessment of peripheral arterial disease (PAD), it has several limitations necessitating alternative noninvasive diagnostic tools. This study assesses the diagnostic accuracy of ABPI compared with Doppler arterial waveforms (DAWs) to detect PAD. The authors searched Embase and MEDLINE for original studies that reported sensitivities and specificities for both the ABPI and DAW. Four studies were included representing 657 patients (58.8% men) with a mean age of 63.4 years. The authors detected overall higher sensitivities using DAW compared with ABPI but higher specificities with ABPI compared with DAW. In conclusion, because of the higher sensitivity and lower specificity of DAW compared with ABPI, the authors recommend DAW as a potential screening tool for PAD. To confirm these results, larger sample sizes and comparative trials with homogeneous reference standards and patient populations are required. In addition, DAW is not easily documented for everyday bedside practice in the community. With COVID-19 restrictions, an audible handheld Doppler signal may act as a reproducible equivalent to DAW and thus facilitate timely, safe application of compression therapy at point-of-care.

Commentary: Demystifying Doppler - revisiting a vital diagnostic tool.

Doppler is the most commonly utilised vascular assessment tool by podiatrists in Australia and the United Kingdom. Doppler is a key component of many international guidelines for vascular assessment. Used alongside pressure measurements such as ankle and toe-brachial indices, Doppler assists podiatrists to diagnose, triage and subsequently manage patients with peripheral arterial disease. This commentary aims to clarify the importance, technique, and interpretation of continuous wave handheld Doppler in podiatry practice. This commentary presents discussion on the equipment and optimal test conditions for use of Doppler, and guidance on the technique required in podiatry clinical practice. Furthermore, there is a focus on interpretation of the output from Doppler including both audio and visual output. There is in depth discussion about identifying pathology and integration into the clinical management plan.

Ankle- and Toe-Brachial Index for Peripheral Artery Disease Identification: Unlocking Clinical Data Through Novel Methods.

BACKGROUND: Despite its high prevalence and clinical impact, research on peripheral artery disease (PAD) remains limited due to poor accuracy of billing codes. Ankle-brachial index (ABI) and toe-brachial index can be used to identify PAD patients with high accuracy within electronic health records. METHODS: We developed a novel natural language processing (NLP) algorithm for extracting ABI and toe-brachial index values and laterality (right or left) from ABI reports. A random sample of 800 reports from 94 Veterans Affairs facilities during 2015 to 2017 was selected and annotated by clinical experts. We trained the NLP system using random forest models and optimized it through sequential iterations of 10-fold cross-validation and error analysis on 600 test reports and evaluated its final performance on a separate set of 200 reports. We also assessed the accuracy of NLP-extracted ABI and toe-brachial index values for identifying patients with PAD in a separate cohort undergoing ABI testing. RESULTS: The NLP system had an overall precision (positive predictive value) of 0.85, recall (sensitivity) of 0.93, and F1 measure (accuracy) of 0.89 to correctly identify ABI/toe-brachial index values and laterality. Among 261 patients with ABI testing (49% PAD), the NLP system achieved a positive predictive value of 92.3%, sensitivity of 83.1%, and specificity of 93.1% to identify PAD when compared with a structured chart review. The above findings were consistent in a range of sensitivity analysis. CONCLUSIONS: We successfully developed and validated an NLP system for identifying patients with PAD within the Veterans Affairs electronic health record. Our findings have broad implications for PAD research and quality improvement.