Sensitivity and Specificity of Pulse Oximetry for Identification of Peripheral Artery Disease: A Systematic Review.

BACKGROUND: Lower limb peripheral artery disease (PAD) is associated with poor outcomes including ulceration, gangrene, amputations, and mortality. Clinicians therefore routinely perform point-of-care tests in high-risk populations to identify PAD and subsequently implement cardiovascular management and appropriate interventions. Pulse oximetry has been suggested as a useful adjunct test for identifying PAD. OBJECTIVE: The aim of this systematic review was to determine the sensitivity and specificity of pulse oximetry in the lower limb for identifying PAD. METHODS: MEDLINE, EMBASE, and CINAHL were searched up until January 10, 2023, to identify studies of sensitivity and specificity of pulse oximetry that used criterion standard diagnostic imaging as a reference standard. Two authors screened articles for inclusion and appraised quality of included studies using the Quality Appraisal for Diagnostic Accuracy Studies, version 2. RESULTS: A total of 6371 records were screened, and 4 were included. The included studies had a total of 471 participants, with an age range of 41 to 80.6 years. All studies were cross-sectional and conducted in hospital settings. Sensitivity values for pulse oximetry compared with diagnostic imaging in identifying PAD ranged from 44% to 76%, and specificity values ranged from 85% to 96%. There was no consensus regarding measurement techniques and diagnostic thresholds for pulse oximetry, which precluded meta-analysis. CONCLUSIONS: There is currently inadequate evidence to support the use of pulse oximetry for identifying PAD. Current evidence suggests that pulse oximetry has low levels of sensitivity and is therefore likely to miss PAD when it is present.

Factors influencing diabetes-related foot ulcer healing in Australian adults: A prospective cohort study.

OBJECTIVE: Diabetes-related foot ulceration (DFU) is a common limb-threatening condition, which is complex and subsequently challenging to manage. The aim of this study was to determine the contribution of a range of clinical and social factors to the healing of diabetes-related foot ulceration in an Australian population. RESEARCH DESIGN AND METHODS: This was a prospective cohort study of individuals with diabetes-related foot ulceration (DFU). Age, sex, medical history, medications, dietary supplementation (e.g. vitamin C intake) and smoking history were elicited at baseline. The index of relative socio-economic disadvantage (IRSD) was calculated. The Australian Eating Survey and International Physical Activity Questionnaire-short were administered. Wound history, size, grade, time to healing and infection were captured and monitored over 6 months. Logistic regression was performed to determine the relationship between healing and diet quality, toe systolic pressure, wound size at, IRSD, infection and previous amputation. RESULTS: A total of 117 participants were included. The majority were male n = 96 (82%), socio-economically disadvantaged (mean IRSD 965, SD 60), and obese (BMI 36 kg/m2 , SD 11) with a long history of diabetes (20 years, SD 11). Wounds were predominantly neuropathic (n = 85, 73%) and classified 1A (n = 63, 54%) on the University of Texas wound classification system with few infections (n = 23, 16%). Dietary supplementation was associated with 4.36 increased odds of healing (95% 1.28-14.84, p = 0.02), and greater levels of socio-economic advantage were also associated with increased odds of healing (OR 1.01, 95% CI 1.01-1.02, p = 0.03). CONCLUSIONS: In this cohort study of predominantly neuropathic, non-infected DFU, individuals who had greater levels of socio-economic advantage had significantly greater odds of DFU healing. Diet quality was poor in most participants, with individuals taking supplementation significantly more likely to heal.

Relationship Between Diabetes-Related Large-Fiber Neuropathy and Dorsiflexion Range of Motion at the Ankle and First Metatarsophalangeal Joints.

BACKGROUND: Diabetes-related peripheral neuropathy (DPN) and limited joint mobility of the foot and ankle are implicated in the development of increased plantar pressures and diabetes-related foot ulcers. The extent of this relationship has not been conclusively established. We aimed to determine the relationship between ankle joint and first metatarsophalangeal joint dorsiflexion range of motion and DPN using a cross-sectional observational study design. METHODS: Primary outcomes were DPN status, ankle joint range of motion (extended and flexed knee lunge tests), and nonweightbearing first metatarsophalangeal joint range of motion. Correlations were performed using Pearson r, and hierarchical regression analyses were undertaken to determine the independent contribution of DPN to the variance in dorsiflexion range of motion of ankle and first metatarsophalangeal joints using standardized ß regression coefficients, controlling for age, sex, body mass index, diabetes duration, and hemoglobin A1c level. RESULTS: One hundred one community-dwelling participants (mean ± SD age, 65.0 ± 11.2 years; 55 men; 97% type 2 diabetes; mean ± SD diabetes duration, 8.7 ± 7.8 years; 23% with DPN) were recruited. Diabetes-related peripheral neuropathy demonstrated significant correlations with reduced range of motion at the ankle joint (knee extended: r = -0.53; P < .001 and knee flexed: r = -0.50; P < .001) and the first metatarsophalangeal joint (r = -0.37; P < .001). Also, DPN made significant, unique contributions to the regression models for range of motion at the ankle joint (knee extended: r2 change = 0.121; ß = -0.48; P < .001 and knee flexed: r2 change = 0.109; ß = -0.45; P < .001) and first metatarsophalangeal joint (r2 change = 0.037; ß = -0.26; P = .048). CONCLUSIONS: These findings suggest that DPN contributes to reduced ankle and first metatarsophalangeal joint range of motion. Due to the established link between reduced ankle and first metatarsophalangeal joint range of motion and risk of diabetes-related foot ulcer, we recommend that clinicians assess dorsiflexion range of motion at these joints as part of routine foot assessment in people with diabetes, especially those with DPN. Globally, approximately 436 million adults aged 20 to 79 years are living with diabetes.1 Diabetes is the leading cause of lower-limb amputation and is associated with a lifetime incidence of diabetes-related foot ulcer (DFU) of up to 34%.2 Diabetes-related peripheral neuropathy (DPN) affects approximately 30% to 50% of people with diabetes3 and is one of the most significant risk factors for the development of DFU and amputation.4 Diabetes-related peripheral neuropathy occurs as a result of neural ischemia and perineural edema causing neural demyelination, affecting nerve conductivity.5 In the presence of DPN, intrinsic foot muscle wasting can lead to the development of foot deformities such as digital clawing, which, when coupled with structural and functional changes to the skin, make it less resistant to shear forces and further increase plantar pressure and risk of DFU.6,7.

Cutaneous microvascular reactivity in Charcot neuroarthropathy: a systematic review and meta-analysis.

BACKGROUND: To systematically evaluate the literature investigating the relationship between cutaneous microvascular reactivity in the foot of adults with diabetes-related Charcot neuroarthropathy compared to a non-Charcot adult control group. METHODS: A systematic search was conducted to June 2021 using the biomedical databases EBSCO Megafile Ultimate, Cochrane Library and EMBASE. Original research conducting comparative investigation of cutaneous microvascular reactivity in the foot of adults with diabetes and any pattern of acute or chronic Charcot neuroarthropathy and any non-Charcot adult control groups were included. A modified Critical Appraisal Skills Programme tool was used for quality appraisal. Cutaneous microvascular reactivity in diabetes-related Charcot neuroarthropathy data were synthesised and meta-analysis conducted where possible. RESULTS: The search strategy identified 1,684 articles, with seven eligible for inclusion. Included studies used various methodologies and equipment to assess cutaneous microvascular reactivity in 553 participants (162 with Charcot neuroarthropathy). Cutaneous microvascular reactivity in Charcot neuroarthropathy groups was impaired compared to uncomplicated diabetes groups. Meta-analysis investigating the difference in response to thermal hyperaemia demonstrated a significant difference in cutaneous microvascular reactivity between Charcot neuroarthropathy and peripheral neuropathy with a large, pooled effect size (SMD 1.46 95% CI: 0.89-2.02) and low heterogeneity (I2 = 4%, T2 = 0.01) indicating that the cutaneous microvascular response is more impaired in peripheral neuropathy than in Charcot neuroarthropathy. CONCLUSIONS: Charcot neuroarthropathy is associated with greater cutaneous microvascular reactivity in the periphery relative to diabetes cohorts with diabetes-related peripheral neuropathy alone. It is unknown if this occurs prior to, or as a result of, Charcot neuroarthropathy.

Factors influencing lower extremity amputation outcomes in people with active foot ulceration in regional Australia: A retrospective cohort study.

Australia has the second highest rate of non-traumatic lower extremity amputation (LEA) globally. Australia's large geographical size is one of the biggest challenges facing limb preservation services and may be contributing to LEA. The aim of this study was to determine what factors contribute to the likelihood of LEA in people with active foot ulceration in regional Australia. This retrospective cohort study audited patients with active foot ulceration in a multidisciplinary high risk foot service (HRFS) in regional Australia. Neurological, vascular and wound characteristics were systematically extracted, along with demographic information. Participants were followed for at least 12 months until healing or LEA occurred. Correlations between LEA and clinical and demographic characteristics were assessed using the Pearson's product moment correlation coefficient and chi squared test for independence. Significant variables (p < 0.05) were included in the model. Direct logistic regression assessed the independent contribution of significantly correlated variables on the likelihood of LEA. Of note, 1876 records were hand screened with 476 participants (25%) meeting the inclusion criteria. Geographical distance from the HRFS, toe systolic pressure (TSP), diabetes and infection were all significantly correlated with LEA and included in the logistic regression model. TSP decrease of 1 mmHg (OR 1.02, 95% CI 1.01-1.03), increased geographical distance (1 km) from HRFS (OR 1.006, 95% CI 1.001-1.01) infection (OR 2.08, 95% CI 1.06-4.07) and presence of diabetes (OR 3.77, 95% CI 1.12-12.65) were all significantly associated with increased likelihood of LEA. HRFS should account for the disparity in outcomes between patients living in close proximity to their service, compared to those in rural areas. Optimal management of diabetes, vascular perfusion and control of infection may also contribute to preventing LEA in people with active foot ulceration.

The ankle brachial index in people with and without diabetes: intra-tester reliability.

BACKGROUND: The ankle-brachial index (ABI) is widely used for determining the presence and severity of peripheral arterial disease (PAD), and current guidelines suggest it should be used to monitor possible progression in affected individuals. It is therefore important that the technique demonstrates adequate reliability for repeated measurements. Existing studies suggest that the ABI is reliable in the general population however, there is a lack of evidence for the reliability of the ABI in people with diabetes. The aim of this study was to investigate the intra-tester reliability of the ABI in people with and without diabetes. METHODS: Eighty-five participants (40 with and 45 without diabetes) underwent ankle and brachial systolic blood pressure measurements by a single clinician during two testing sessions. Intraclass correlation coefficients (ICC), their 95% limits of agreement, standard error of measurement and minimal detectable change were determined. RESULTS: Intra-tester reliability of the ABI was found to be good (ICC: 0.80), however sub-group analysis of participants with and without diabetes found that ABI was slightly less reliable in people with diabetes (ICC: 0.78) than in those without (ICC: 0.82). The relatively large limits of agreement (- 0.16 to 0.16), standard error of measurement (0.03 overall, 0.04 for the diabetes group), and minimal detectable change (0.08 overall, 0.11 for the diabetes group) suggest that a large change in ABI is required for it to demonstrate a true change rather than the result of measurement variability. The minimal detectable change for the ABI was 0.08 overall, and 0.11 for the diabetes group. CONCLUSIONS: The ABI demonstrated good reliability in all groups analysed. However, the wide limits of agreement and considerable standard error of measurement obtained support the use of multiple methods of vascular assessment for ongoing monitoring of lower limb vascular status.

Accurate Noninvasive Arterial Assessment of the Wounded Lower Limb: A Clinical Challenge for Wound Practitioners.

Arterial investigations are an essential part of lower extremity wound assessment. The results of these investigations assist the wound clinician to determine the etiology of the wound, predict healing capacity, and inform further management. There are a number of noninvasive testing methods available to practitioners, all with varying levels of reliability and accuracy. Clinical wound assessment guidelines give varied recommendations when it comes to lower limb vascular assessment in the presence of a wound. This leaves clinicians with little guidance on how to choose the most appropriate test, and uncertainty remains about which tests provide the most accurate information in different patient-specific contexts. Conditions such as advanced age, diabetes, and renal disease are known to affect the accuracy of some commonly used lower limb arterial assessment methods, and alternate testing methods should be considered in these cases. This seminal review discusses the reliability and accuracy of lower limb vascular assessment methods used to guide lower limb arterial assessment in the presence of wounds.

Non-invasive assessment of vibration perception and protective sensation in people with diabetes mellitus: inter- and intra-rater reliability.

BACKGROUND: Testing of protective sensation and vibration perception are two of the most commonly used non-invasive methods of screening for diabetes-related peripheral neuropathy (DPN). However, there is limited research investigating the reliability of these tests in people with diabetes. The aim of this study was to determine the inter- and intra-rater reliability of methods used to test vibration perception and protective sensation in a community-based population of adults with type 2 diabetes. METHODS: Three podiatrists with varying clinical experience tested four- and 10-site, 10 g monofilament and vibration perception threshold (VPT). In a separate cohort, the reliability of a graduated tuning fork as well as two methods of conventional tuning fork (on/off method and dampening method) was undertaken by a new graduate podiatrist and podiatrist with one-year's clinical experience. The intra- (Cohen's К) and inter-rater (Cohen's or Fleiss' К) reliability of each test was determined. RESULTS: Fifty participants (66% male, 100% type 2, 32% with DPN) underwent monofilament and neurothesiometer testing with 44 returning for the retest. Twenty-four participants (63% male, 100% type 2, 4% with DPN) underwent tuning fork testing and returned for retest. All tests demonstrated acceptable inter-rater reliability ranging from moderate (10-site monofilament, К: 0.54, CI: 0.38-0.70, p = 0.02) to substantial (graduated tuning fork, К: 0.68, CI: 0.41-0.95, p < 0.01). The 10-site monofilament (К: 0.44-0.77) outperformed the 4-site test (К: 0.34-0.67) and the dampened tuning fork method (К: 0.41-0.49) showed lower intra-rater reliability compared to both conventional (К: 0.52-0.57) and graduated methods (К: 0.50-0.57). CONCLUSION: We support the current recommendations of using more than one test to screen and monitor progression of DPN. Four- and 10-site 10 g monofilament testing have similarly acceptable levels of reliability and the neurothesiometer is the most reliable method of assessing vibration perception function. Use of a graduated tuning fork was slightly more reliable than other methods of tuning fork application however all had substantial reliability. Years of clinical experience only marginally affected test reliability overall and due to subjective nature of the tests we suggest that testing should be performed regularly and repetitively.

Relationship between lower limb vascular characteristics, peripheral arterial disease and gait in rheumatoid arthritis.

OBJECTIVES: Rheumatoid arthritis (RA) is associated with higher risk of atherosclerotic vascular disease, including peripheral arterial disease (PAD). The aim of this study was to measure lower limb vascular characteristics (indicative of PAD), using non-invasive chairside testing methods, in people with RA compared to matched controls, and to determine the association between vascular characteristics and gait velocity as a measure of functional capacity in people with RA. METHODS: This was a cross-sectional pilot study which measured lower limb vascular characteristics (bilateral continuous wave Doppler, toe brachial index [TBI] and ankle brachial index [ABI]) and gait velocity (6-m walk test) in people with RA and controls. Differences in vascular characteristics between groups were determined using linear regression models, and associations between vascular characteristics and gait were determined using logistic regression models. RESULTS: Seventy-two participants were included: 34 participants with RA mean disease duration 26.2 (SD 12.1) and 38 age- and sex-matched controls. The control group contained 30 females (79%), and the RA group had 28 females (82%). There were no significant differences between the RA and control groups for lower limb vascular characteristics. People with RA walked significantly slower compared to controls (1.10 m/s vs 0.91 m/s, P < .001). People with RA who had abnormal TBI, or abnormal qualitative Doppler walked significantly slower compared to those with normal TBI (0.86 m/s vs 0.95 m/s, P = .043 and 0.81 m/s, vs 0.93 m/s, P = .028). There was no significant association between ABI and gait velocity. CONCLUSION: This study did not identify different lower limb vascular characteristics in people with RA compared to matched controls. However, in people with RA, abnormal Doppler and TBI results are associated with slower walking velocity.

Lower limb vascular assessment techniques of podiatrists in the United Kingdom: a national survey.

BACKGROUND: Podiatric vascular assessment practices in the United Kingdom (UK) are currently unknown. This study aimed to describe the current practices for performing lower limb vascular assessments by podiatrists in the UK, and, to investigate the effect of practitioner characteristics, including education level and practice setting, on the choice of tests used for these assessments. METHODS: A cross-sectional observational online survey of registered podiatrists in the UK was conducted using SurveyMonkey® between 1st of July and 5th of October 2018. Item content related to: practitioner characteristics, vascular testing methods, barriers to completing vascular assessment, interpretation of vascular assessment techniques, education provision and ongoing management and referral pathways. Descriptive statistics were performed, and multinomial logistic regression analyses were used to determine whether practitioner characteristics could predict the choice of vascular tests used. RESULTS: Five hundred and eighty five participants accessed the online survey. After drop-outs and exclusions, 307 participants were included in the analyses. Comprehensive vascular assessments had most commonly been performed once (15.8%) or twice (10.4%) in the past week. The most common indicators for performing vascular assessment were symptoms of suspected claudication (89.3%), suspected rest pain (86.0%) and history of diabetes (85.3%). The most common barrier to performing vascular assessment was time constraints (52.4%). Doppler examination (72.3%) was the most frequently reported assessment type, with ankle-brachial index (31.9%) and toe brachial index (5.9%) less frequently performed. There were variable interpretations of vascular test results. The most common topic for education was smoking cessation (69.5%). Most participants (72.2%) were confident in determining ongoing management, with the majority referring to the patient's general practitioner (67.6%). Practitioner characteristics did not predict the types of vascular tests performed. CONCLUSION: The majority of vascular assessments currently performed by podiatrists in the UK are inconsistent with UK or international vascular guidelines and recommendations. Despite this, most podiatrists felt confident in diagnosing, referring and managing patients with peripheral arterial disease (PAD), however many felt they needed more education to feel confident to assist patients with PAD to manage their cardiovascular risk factors.

How does a short period of exercise effect toe pressures and toe-brachial indices? A cross-sectional exploratory study.

BACKGROUND: Whilst post exercise ankle-brachial indices (ABI) are commonly used to help identify peripheral arterial disease (PAD), the role of post exercise toe pressures (TP) or toe-brachial indices (TBI) is unclear. The aim of this study was to determine, in a population without clinical signs of PAD, the effect that 30 s of weight-bearing heel raises has on TP and TBI values. Additionally, the ability of resting TP and TBI values to predict change in post-exercise values using the heel raise method was investigated. METHODS: Participants over the age of 18 with a resting TBI of ≥0.60 and ABI between 0.90 and 1.40, without diabetes, history of cardiovascular disease and not currently smoking were included. Following ten minutes of supine rest, right TP and bilateral brachial pressures were performed in a randomized order using automated devices. Participants then performed 30 s of weight-bearing heel raises, immediately after which supine vascular measures were repeated. Data were assessed for normality using the Shapiro-Wilk test. For change in TP and TBI values the Wilcoxon Signed-Rank Test was performed. For correlations between resting and change in post exercise values, the Spearman Rank Order Correlations were performed, and where significant correlation identified, a linear regression undertaken. RESULTS: Forty-eight participants were included. A statistically significant decrease was seen in the median TP from resting 103.00 mmHg (IQR: 89.00 to 124.75) to post exercise 98.50 mmHg (IQR: 82.00 to 119.50), z = - 2.03, p = 0.04. This difference of 4.50 mmHg represents a 4.37% change and is considered a small effect size (r = 0.21). The median TBI also demonstrated a statistically significant decrease from resting 0.79 (IQR: 0.68 to 0.94) to post exercise 0.72 (IQR: 0.60 to 0.87), z = - 2.86, p = < 0.01. This difference of 0.07 represents an 8.86% change and is considered a small effect size (r = 0.29). Linear regression demonstrated that resting TBI predicted 22.4% of the variance in post exercise TBI, p = < 0.01, coefficients beta - 0.49. CONCLUSIONS: Thirty seconds of weight-bearing heel raises resulted in a similar decrease in TBI values seen in longer periods of exercise. TP values also showed a decrease post exercise; however this was contrary to previous studies.

How sensitive and specific is continuous-wave Doppler for detecting peripheral arterial disease in people with and without diabetes? A cross-sectional study.

BACKGROUND: Continuous-wave Doppler is frequently used for detecting peripheral arterial disease in patients with diabetes; however, there is limited evidence investigating diagnostic accuracy. This study aimed to determine sensitivity and specificity of continuous-wave Doppler for detecting peripheral arterial disease in populations with, and without, diabetes and to investigate the influence of disease severity on sensitivity of continuous-wave Doppler for detecting peripheral arterial disease. RESULTS: Data from 396 participants were included. Using colour Duplex ultrasound as reference standard (N=66), printed continuous-wave Doppler waveform analysis sensitivity was 81.75% (95% confidence interval: 76.75 to 85.88) and specificity 89.34% (95% confidence interval: 82.62 to 93.67). Printed continuous-wave Doppler waveform analysis sensitivity for peripheral arterial disease was comparable to sensitivity calculated using angiography as the reference standard (81.67%; 95% confidence interval: 69.56 to 90.48). Sensitivity and specificity were unaffected by diabetes diagnosis (n = 176), sensitivity 82.76% (95% confidence interval: 74.86 to 88.55), and specificity 88.33% (95% confidence interval: 77.82 to 94.23). CONCLUSION: Continuous-wave Doppler is a fair assessment tool for peripheral arterial disease in a community-based sample with suspected peripheral arterial disease. Diagnostic accuracy of continuous-wave Doppler for peripheral arterial disease is unaffected by the presence of diabetes.

Diagnostic accuracy of the postexercise ankle-brachial index for detecting peripheral artery disease in suspected claudicants with and without diabetes.

The postexercise ankle-brachial index (ABI) is recommended in patients with normal resting ABI when peripheral artery disease (PAD) is suspected. The aims of this study were to determine the comparative diagnostic accuracy of the resting and postexercise ABI for detecting PAD, and, the effect of the presence of diabetes on these. Three methods of interpretation currently in use were also investigated: a reduction in postexercise ABI by >20% compared to resting ABI, an ABI value of ≤0.90 postexercise, or a reduction in systolic ankle pressure of >30 mmHg postexercise. This retrospective study used colour duplex ultrasound (CDU) as the reference standard. In 278 limbs (whole group), the resting ABI had an overall area under the curve (AUC) of 0.71, with the postexercise ABI yielding a similar diagnostic accuracy of AUC 0.72. In the non-diabetes group ( n=171), the resting ABI had an overall AUC of 0.74 and the postexercise ABI had a similar AUC of 0.76. In the diabetes group ( n=107), overall accuracy was reduced compared to the non-diabetes group, with the resting ABI having an overall AUC of 0.65 and the postexercise ABI yielding a similar accuracy with an AUC of 0.64. The overall diagnostic accuracy of the postexercise ABI for diagnosing PAD was not greatly improved compared to resting ABI. Given the lower overall diagnostic accuracy in the diabetes group, both the resting and the postexercise ABI results in diabetes populations should be interpreted with caution. There is a risk of undiagnosed disease if relying on these results alone to determine lower limb vascular status.

Diagnostic accuracy of resting systolic toe pressure for diagnosis of peripheral arterial disease in people with and without diabetes: a cross-sectional retrospective case-control study.

BACKGROUND: The resting systolic toe pressure (TP) is a measure of small arterial function in the periphery. TP is used in addition to the ankle-brachial index when screening for peripheral arterial disease (PAD) of the lower limb in those with diabetes, particularly in the presence of lower limb medial arterial calcification. It may be used as an adjunct assessment of lower limb vascular function and as a predictor of wound healing. The aim of this study was to determine the diagnostic accuracy of TP for detecting PAD in people with and without diabetes. METHODS: This was a retrospective case-control study. Two researchers extracted information from consecutive patient records, including TP measurements, colour Duplex ultrasound results, demographic information, and medical history. Measures of diagnostic accuracy were determined by receiver operating curve (ROC) analysis, and calculation of sensitivity, specificity, and positive and negative likelihood ratios. RESULTS: Three hundred and nintey-four participants with suspected PAD were included. In the diabetes group (n = 176), ROC analysis of TP for detecting PAD was 0.78 (95%CI: 0.69 to 0.84). In the control group (n = 218), the ROC of TP was 0.73 (95%CI: 0.70 to 0.80). TP had highest sensitivity when anatomical distribution of disease was both proximal and distal (diabetes group: 79.49%, the control group: 82.61%). TP yielded highest sensitivity in mild disease (50-75% stenosis) in diabetes group, (81.82%) and moderate disease (>75% stenosis) in control group (80.77%). CONCLUSIONS: Our findings indicate that TPs are useful to assist in diagnosing PAD in clinical practice, however, results should be interpreted with caution due to the small probability of PAD being present with a negative test.

Non-invasive lower limb small arterial measures co-segregate strongly with foot complications in people with diabetes.

AIMS: It is unclear how well non-invasive lower-limb vascular assessments can identify those at risk of foot complications in people with diabetes. We aimed to investigate the relationship between a history of foot complication (ulceration or amputation) and non-invasive vascular assessments in people with diabetes. METHODS: Bilateral ankle-brachial index (ABI), toe brachial index (TBI) and continuous wave Doppler (CWD) were performed in 127 adults with diabetes (97% type 2; age 66.08±11.4years; 55% men; diabetes duration 8.8±7.6years; 28% on insulin therapy; 31% with foot complication history. Correlations were performed between known risk factors for, and documented history of, foot complication. Regression analysis was used to determine the effect of TBI on the likelihood of a prior foot complication. RESULTS: By logistic regression, the likelihood of foot complication history was highest in those with TBI <0.6 (OR=7.74, p=0.001); then longer diabetes duration (OR=1.06, p=0.05). HbA1c did not independently predict history of foot complications (OR=1.10, p=0.356). CONCLUSIONS: Likelihood of previous foot complication in this population was ~8 times higher when TBI was <0.6. Such clinical risk profiling was not shown by other non-invasive measures. Prioritizing TBI as a measure of lower-limb vascular disease may be useful to prospectively identify those at risk of diabetic foot complications.

A targeted screening method for non-invasive vascular assessment of the lower limb.

BACKGROUND: Podiatrists routinely perform non-invasive lower limb vascular assessment, however frequently cite time as a major barrier in performing regular assessment. The aim of this study was to develop an evidence-based vascular assessment method to guide podiatrists' decision-making processes to aid in timely vascular assessment in at risk populations. METHOD: The sample underwent brachial pressure measurement, ankle pressures, toe pressure and Doppler waveform with colour duplex ultrasound (CFDU) used as the reference standard. Both the targeted screening method and the American Heart Association (AHA) guideline for vascular screening were then applied to the data set and sensitivity and specificity of each method was calculated. RESULTS: One hundred nineteen participants were included. Sensitivity of the targeted screening method (62%, 95% CI 47.17-75.35) was higher than the AHA method (49%, 95% CI 34.75-63.40), however, specificity of the AHA method (94%, 95% CI 85.62-98.37) was higher than the targeted screening method (85%, 95% CI 74.26-92.60). Diagnostic accuracy was similar with the AHA method yielding 74% diagnostic accuracy and the targeted screening method 73%. CONCLUSION: The targeted screening method and the broad international guideline demonstrated similar accuracy, however clinicians may save time using the targeted screening method. This study highlights the difficulties in obtaining accuracy in lower limb vascular assessment in general.

Flip-flop footwear with a moulded foot-bed for the treatment of foot pain: a randomised controlled trial.

BACKGROUND: Foot pain is a common problem affecting up to 1 in 5 adults and is known to adversely affect activities of daily living and health related quality of life. Orthopaedic footwear interventions are used as a conservative treatment for foot pain, although adherence is known to be low, in part due to the perception of poor comfort and unattractiveness of the footwear. The objective of this trial was to assess the efficacy of flip-flop style footwear (Foot Bio-Tec©) with a moulded foot-bed in reducing foot pain compared to participant's usual footwear. METHODS: Two-arm parallel randomised controlled trial using computer generated random allocation schedule at an Australian university podiatry clinic. 108 volunteers with disabling foot pain were enrolled after responding to an advertisement and eligibility screening. Participants were randomly allocated to receive footwear education and moulded flip-flop footwear to wear as much as they were comfortable with for the next 12 weeks (n = 54) or footwear education and instructions to wear their normal footwear for the next 12 weeks (n = 54). Primary outcome was the pain domain of the Foot Health Status Questionnaire (FHSQ). Secondary outcomes were the foot function and general foot health domains of the FHSQ, a visual analogue scale (VAS) for foot pain and perceived comfort of the intervention footwear. RESULTS: Compared to the control group, the moulded flip-flop group showed a significant improvement in the primary outcome measure of the FHSQ pain domain (adjusted mean difference 8.36 points, 95 % CI 5.58 to 13.27, p < 0.01). Statistical and clinically significant differences were observed for the secondary measure of foot pain assessed by a VAS and the FSHQ domains of foot function and general foot health. None of the participants reported any pain or discomfort from the intervention footwear and six (footwear group = 4) were lost to follow up. CONCLUSIONS: Our results demonstrate that flip-flop footwear with a moulded foot-bed can have a significant effect on foot pain, function and foot health and might be a valuable adjunct therapy for people with foot pain. TRIAL REGISTRATION: ACTRN12614000933651 . Retrospectively registered: 01/09/2014.

A systematic review of the sensitivity and specificity of the toe-brachial index for detecting peripheral artery disease.

The toe-brachial index (TBI) is used as an adjunct to the ankle-brachial index (ABI) for non-invasive lower limb vascular screening. With increasing evidence suggesting limitations of the ABI for diagnosis of vascular complications, particularly in specific populations including diabetes cohorts, the TBI is being used more widely. The aim of this review was to determine the sensitivity and specificity of the TBI for detecting peripheral artery disease (PAD) in populations at risk of this disease. A database search was conducted to identify current work relating to the sensitivity and specificity of toe-brachial indices up to July 2015. Only studies using valid diagnostic imaging as a reference standard were included. The QUADAS-2 tool was used to critically appraise included articles. Seven studies met the inclusion criteria. Sensitivity of the TBI for PAD was reported in all seven studies and ranged from 45% to 100%; specificity was reported by five studies only and ranged from 16% to 100%. In conclusion, this review suggests that the TBI has variable diagnostic accuracy for the presence of PAD in specific populations at risk of developing the disease. There was a notable lack of large-scale diagnostic accuracy studies determining the diagnostic accuracy of the TBI in detecting PAD in different at-risk cohorts. However, standardised normal values need to be established for the TBI to conclusively determine the diagnostic accuracy of this test.

Non-invasive vascular assessment in the foot with diabetes: sensitivity and specificity of the ankle brachial index, toe brachial index and continuous wave Doppler for detecting peripheral arterial disease.

BACKGROUND & AIMS: Non-invasive lower limb vascular assessment in people at risk of peripheral arterial disease (PAD) including those with diabetes is crucial. There is evidence that standard assessment techniques such as the ankle-brachial index (ABI) may be less effective in people with diabetes. However there is limited evidence for other frequently used tests including continuous wave Doppler (CWD), and the toe-brachial index (TBI). The aim of this study was to determine the sensitivity and specificity of, ABI, CWD and TBI in a population with, and without diabetes. METHODS: Participants with and without diabetes who met current guidelines for vascular screening were recruited, and CWD waveforms, an ABI and a TBI were obtained from the right lower limb. Diagnostic accuracy was determined using colour duplex ultrasound (CFDU). Receiver operating characteristic curves were calculated. RESULTS: 117 participants were recruited, seventy-two with diabetes and forty-five without diabetes. CWD had the highest sensitivity in people with diabetes (74%) and without (84%). CWD also had the highest specificity in people with diabetes (74%) and without (84%) compared to both TBI and ABI. In participants with diabetes, the ABI was a poor test, area under the curve: 0.58 (p=0.27). CONCLUSIONS: CWD waveform is more likely to detect significant PAD compared to ABI and TBI in people with and without diabetes.