The Incidence and Outcomes of Major Limb Amputation in New Zealand from 2010 to 2021.

Background: Major limb amputation (MLA) can be a common outcome due to severe peripheral artery disease (PAD) and diabetic foot disease (DFD), and it carries a significant mortality burden. In New Zealand (NZ), there is little documentation of the incidence rate and mortality after MLA. The aim was to report the national crude and standardised rates and the mortality post MLA. Methods: This retrospective observational study included all MLAs that occurred within NZ from 1/1/2010 to 31/12/2021 due to DFD and/or PAD. Two national databases (National Minimum Dataset and the Australasian Vascular Audit) were utilised. The crude rates were calculated as cases per 100,000 in the NZ population per year including all ages (using the 2013 and 2018 NZ census figures). The age-standardised rates used the World Health Organization standard population. Post-operative mortality was calculated from the date of first hospitalisation for MLA. Results: From 2010 to 2021, there were 5293 MLA procedures in 4242 patients. On average, there were 8.5 MLAs per week and 441.1 MLAs annually. The overall crude rate was 9.44 per 100,000, and the standardised rate was 6.12 per 100,000. Over the 12 years, the crude rate decreased by 22% (p < 0.001), and the standardised rate decreased by 20.4% (p < 0.001). After MLA, the 30-day and 1-year mortality was 9.5% and 29.6%, respectively. From 2010 to 2021, the relative reduction in 30-day mortality was 45.1% (p < 0.001), and the reduction in 1-year mortality was 24.5% (p < 0.001). Increasing age, female sex and end-stage renal failure were predictors of 30-day and 1-year mortality. Conclusions: A considerable number of MLAs occur in NZ, with substantial perioperative mortality; however, the national incidence rates and mortality have improved over the last 12 years. This data might serve as benchmark to further reduce MLAs and improve patient outcomes.

Association of Pedal Acceleration Time With Healing and Amputation Free Survival in Patients With Ulceration and Gangrene.

OBJECTIVE: Pedal acceleration time (PAT) is a novel non-invasive perfusion measurement that may be useful in the management of patients with ulceration and gangrene. The objective of this study was to report the association between PAT and wound healing, amputation free survival (AFS), and mortality at one year. METHODS: This prospective observational study reviewed all patients who underwent PAT after presentation with ulceration or gangrene from 1 January 2020 to 30 June 2022. PAT was defined as the time (in milliseconds) from the onset of systole to the peak of systole in the mid artery. The final PAT of a limb was used to assess outcomes (presenting PAT if no revascularisation, or post-revascularisation PAT). Wound healing, major limb amputation, and death at one year were collected. Healing was assessed with Fine-Gray competing risks model, AFS via logistic regression, and survival using Cox proportional hazards model. RESULTS: Overall, 265 patients (307 limbs) were included. The median patient age was 71 years and 74.0% (196/265) had diabetes mellitus. Patient demographics were similar among the final PAT category cohorts. Compared with a final PAT category 1, analysis of one year outcomes showed that the final PAT categories 2 - 4 had lower wound healing (category 2, hazard ratio [HR] 0.62, 95% confidence interval [CI] 0.43 - 0.9, p = .012; category 3, HR 0.21, 95% CI 0.08 - 0.58, p = .002; category 4, HR 0.12, 95% CI 0.04 - 0.34, p < .001), lower AFS (category 2, odds ratio [OR] 2.86, 95% CI 1.64 - 5.0, p < .001; category 3, OR 5.1, 95% CI 1.71 - 15.22, p = .003; category 4, OR 12.59, 95% CI 4.34 - 36.56, p < .001), and lower survival (category 2, HR 1.89, 95% CI 1.17 - 3.03, p =.009; category 3, HR 2.37, 95% CI 1.05 - 5.36, p = .039; category 4, HR 4.52, 95% CI 2.48 - 8.21, p < .001). CONCLUSION: The final PAT measurement is associated with wound healing, AFS, and death at one year. PAT may be a valuable tool to assess perfusion of the foot.

A substantial number of patients with rest pain, ulceration or gangrene are unable to undergo current non-invasive perfusion testing-Could another modality be utilised?

Rest pain, ulceration and gangrene are hallmark features of chronic limb-threatening ischaemia (CLTI). Wound healing can be challenging, and this is compounded by an inability to measure lower limb perfusion via non-invasive tools such as toe pressure (TP). Novel perfusion tests, such as pedal acceleration time (PAT), may overcome some limitations. This study aimed to quantify the proportion of patients with CLTI that were unable to undergo TP measurement. Over a three-year duration, 344 consecutive patients with CLTI underwent PAT assessment (403 limbs). Overall, 32% of limbs were unable to undergo first toe TP, and 12.9% were unable to undergo first and second toe TP due to forefoot/digit amputation or tissue loss. Inability to measure first toe TP disproportionately impacted CLTI patients with diabetes compared to patients without diabetes (39.6% limbs (106/268); vs. 17% limbs (23/135); p < 0.001). Novel modalities may provide a useful tool for assessing perfusion in CLTI.

The prescribing of cardioprotective medications and the impact on survival for patients with peripheral artery disease that undergo intervention.

BACKGROUND: Cardiovascular disease guidelines recommend that patients with established peripheral artery disease (PAD) are prescribed antihypertensive, lipid-lowering, and antiplatelet medication to reduce cardiovascular ischaemic events. However, the prescribing of these medications for patients with PAD within New Zealand (NZ) remains undefined. METHODS: This was a retrospective observational cohort study of patients in the Midland region of NZ, that underwent PAD-related percutaneous and surgical intervention between 1st January 2010 and 31st December 2021. Patient level data was collected. The primary outcome was prescribing of cardioprotective medications either before or within 1 year of incident procedure. Secondary outcome was overall survival. RESULTS: There were 2547 patients included. Antihypertensive prescription occurred in 80.7%, lipid-lowering in 77.4% and antithrombotic in 89.9%. Concomitant ischaemic heart disease increased prescription of cardioprotective medications. Women were prescribed less lipid-lowering medication compared to men. Maori men were prescribed less antiplatelet medication compared to non-Maori men. On univariate analysis lipid-lowering and antiplatelet medication showed survival advantage, while antihypertensive and anticoagulation did not. After adjustment for age, sex, end stage renal failure and presence of chronic limb-threatening ischaemia, best medical therapy was associated with better survival (HR 0.88, 95% CI 0.79-0.98, P = 0.02). CONCLUSION: This study highlights areas of deficiency in prescribing of cardioprotective medication in this high-risk group. These could be targets for national quality improvement initiatives.

The use of fetal bovine acellular dermal matrix in severe diabetic foot ulceration and threatened limbs with tissue loss the use of FBADM as an adjunct for complex wounds.

OBJECTIVES: Foot ulceration associated with diabetic foot disease (DFD) and chronic limb-threatening ischaemia (CLTI) presents a complex clinical challenge and failure to heal the wound imposes a significant risk of major limb amputation (MLA). In attempt to accelerate wound healing rates and decrease MLA, tissue engineering research into bio-engineered scaffolds and skin substitutes has become a growing area of interest. Advanced wound therapies such as fetal bovine acellular dermal matrix (FBADM) may have success in the treatment of difficult to heal chronic foot ulcers. The FBADM traps and binds the patients' own epithelial cells to rebuild the dermis layer of the skin. Previous studies have suggested that wounds treated with FBADM had a faster healing rate than wounds managed with conventional dressings. However, these studies excluded foot wounds with chronic exposed bone or tendon, active infection, gangrene, or osteomyelitis and patients with uncontrolled blood glucose levels were excluded. The aim of this study was to assess the efficacy of FBADM for patients admitted to hospital acutely with severe foot ulceration secondary to DFD and CLTI. METHODS: Between February 2020 and December 2021, inpatients admitted acutely at a single tertiary centre with a severe non-healing foot ulcer and had a wound suitable for application of a FBADM after primary debridement were included in the study. A severe non-healing foot wound was defined as a Society for Vascular Surgery Wound, Ischaemia, and foot Infection (WIfI) stage of 3 or 4. Participants were prospectively followed up at regular intervals at a multidisciplinary high-risk diabetic foot clinic until June 2022. The primary endpoint was time to wound closure. The secondary endpoints were number of applications of FBADM, readmission rate and amputation-free survival. RESULTS: There were 22 patients included in the study with a median age of 71 (50-87) years and 15 were male. Five patients had a WIfI stage of 3 and 17 had a WIfI score of 4. Overall, 14 patients required revascularisation procedures (6 open surgery,8 endovascular intervention). A total of 18 patients achieved complete wound healing with a median time to wound healing of 178 (28-397) days. Two patients underwent a MLA and two patients died prior to complete wound healing. The median length of stay was 16.5 (5-115) days, and 4 patients were readmitted to hospital within 12 months. CONCLUSION: FBADM may be a useful adjunct in the acute setting of complex DFD and CLTI ulceration to assist with wound healing. Future comparative prospective studies are required to further validate these preliminary findings.

The utility of hyperspectral imaging in patients with chronic venous disorders.

OBJECTIVE: The underlying pathophysiology of lower limb changes in chronic venous disorders (CVD) may involve alteration in microcirculation and tissue oxygenation. Hyperspectral imaging (HSI) is a noninvasive tool that is used clinically to measure transcutaneous oxygenation in peripheral artery disease and diabetic foot disease. However, there has been little application in venous disease. The aim of this study was to determine if transcutaneous oxygenation in the lower limb, as measured by HSI, changes depending on the clinical component of the Clinical-Etiological-Anatomical-Pathophysiological (CEAP) classification in CVD. METHODS: This was an observational study of patients with CVD recruited from a vascular specialist clinic at a tertiary hospital from January 2020 to January 2021. Participants were allocated to eight groups according to the clinical component of CEAP classification of CVD. Baseline demographic and risk factor information were collected. Transcutaneous oxygenation was measured using HSI at seven sites around the foot and gaiter area in the supine and standing position. Participants rested supine for 15 minutes before the supine measurements and then stood for 15 minutes before the standing measurements. Tissue oxygenation was analyzed over a fixed circular surface area of 79 mm2 at the target location. Calculations of oxyhemoglobin level (artificial unit [AU]), deoxyhemoglobin level (AU), oxygen saturation (%), and temperature (°C) were obtained. The Northern Ethics Committee (18/NTA/78) approved this conduct of the study and participants signed written consent forms. RESULTS: There were 94 participants (164 lower limbs) included in the study. The median age was 59 years and 59 participants (63%) were women. At all sites except the heel, deoxyhemoglobin measurements increased in the standing position compared with the supine position (P < .001). In the gaiter region, there was nearly a doubling in deoxyhemoglobin level at 5 cm above the medial malleolus (supine 43.88 AU vs standing 80.46 AU; P < .001) and 5 cm above the lateral malleolus (supine 46.33 AU vs standing 87.72 AU; P < .001). When measurements were stratified by clinical class of the CEAP classification, there was a greater increase in deoxyhemoglobin levels with increasing clinical class in the standing position (P < .001). This finding was not observed in the supine measurements. CONCLUSIONS: In CVD, HSI shows an increase in deoxyhemoglobin in the standing compared with supine position, particularly in the gaiter region. Furthermore, standing deoxyhemoglobin increases as the CEAP clinical class increases. Thus, this noninvasive tool may respond to venous physiology and may supplement the clinical class of the CEAP classification system.

The Incidence of Chronic Limb-Threatening Ischemia in the Midland Region of New Zealand over a 12-Year Period.

The epidemiology of severe PAD, as characterized by short-distance intermittent claudication (IC) and chronic limb-threatening ischemia (CLTI), remains undefined in New Zealand (NZ). This was a retrospective observational cohort study of the Midland region in NZ, including all lower limb PAD-related surgical and percutaneous interventions between the 1st of January 2010 and the 31st of December 2021. Overall, 2541 patients were included. The mean annual incidence of short-distance IC was 15.8 per 100,000, and of CLTI was 36.2 per 100,000 population. The annual incidence of both conditions was greater in men. Women presented 3 years older with PAD (p < 0.001). Patients with short-distance IC had lower ipsilateral major limb amputation at 30 days compared to CLTI (IC 2, 0.3% vs. CLTI 298, 16.7%, p < 0.001). The 30-day mortality was greater in elderly patients (<65 years 2.7% vs. ≥65 years 4.4%, p = 0.049), but did not differ depending on sex (females 36, 3.7% vs. males 64, 4.1%, p = 0.787). Elderly age was associated with a worse survival for both short-distance IC and CLTI. There was a worse survival for females with CLTI. In conclusion, PAD imposes a significant burden in NZ, and further research is required in order to reduce this disparity.

Protocol for a prospective observational study: the Australia and New Zealand Diabetic and Ischaemic Foot Outcomes Study (ANZ-DIFOS).

INTRODUCTION: Diabetic foot disease is a common condition globally and is over-represented in indigenous populations. The propensity for patients with diabetic foot disease to undergo minor or major limb amputation is a concern. Diabetic foot disease and lower limb amputation are debilitating for patients and have a substantial financial impact on health services. The purpose of this multicentre study is to prospectively report the presentation, management and outcomes of diabetic foot disease, to validate existing scoring systems and assess long term outcomes for these patients particularly in relation to major limb amputation. METHODS AND ANALYSIS: This is a multisite, international, prospective observational study, being undertaken at Waikato Hospital, New Zealand (NZ); Sir Charles Gairdner Hospital, the Royal Adelaide Hospital and the Queen Elizabeth Hospital, Australia. Consecutive participants with diabetic foot disease that meet inclusion criteria and agree to participate will be recruited from multidisciplinary team diabetic foot clinic, vascular clinic, dialysis and admission to hospital. Follow-up of participants will occur at 1, 3, 6 and 12 months. At recruitment and follow-up reviews, information about service details, demographic and clinical history, wound data and discharge information will be recorded. The primary outcomes are the time to wound healing, major amputation, overall mortality and amputation-free survival at 12 months. This study started in NZ in August 2020 and will commence in Australian sites in early 2021. ETHICS AND DISSEMINATION: New Zealand Central Health and Disability Ethics Committee (20/CEN/122), Waikato DHB Research Department (RDO020044), Quality Improvement HoD Sir Charles Gairdner Hospital (39715) and the Central Adelaide Local Health Network (CALHN) Human Research Ethics Committee (13928). Results will be presented at international conferences and published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ACTRN12621000337875).

Optimising in-patient stays for surgical patients-an analysis utilising the Red and Green Bed Days management system.

AIMS: Red and Green Bed Days is a hospital management system designed to identify delays during in-patient stays. This study quantified days when no activity occurred to progress a patient towards discharge. METHODS: Starting June 2018, 100 consecutive in-patient stays were recorded within the vascular department at Waikato Hospital, New Zealand. A 'green day' occurred when the planned care for that day was achieved. A 'red day' occurred when a patient only received care that did not require an acute bed. The causes of red days were identified. RESULTS: There were 703 total in-patient days, with 37% red days. Patients aged between 60-79 years accounted for 57% of red days. Patients with peripheral arterial disease experienced 77.3% of the red days (severe chronic limb ischaemia 58.1% and acute limb ischaemia 19.2%). Awaiting wound dressing change, acute theatre (vascular and emergency theatre) and interventional procedure accounted for 31.9%, 11.2% and 9.2% of red days respectively. Delays to vascular ultrasound and rehabilitation review each resulted in 8.4% of red days. CONCLUSIONS: This study highlights significant delays during vascular surgery admissions and provides a focus to improve patient quality of life and hospital efficiency.