The Indirect Impact of COVID-19 Pandemic on Lower Extremity Amputations - An Australian Study.

Background: The COVID-19 pandemic has had indirect and deleterious effects on patient health due to interruptions to routine provision of healthcare. This is particularly true for patients with chronic conditions like peripheral vascular disease (PVD). This study aims to evaluate the impact of the pandemic on patients with PVD in Australia by analysing rates of amputation, indications for amputation and urgency of surgery in the pre-pandemic and pandemic periods. Methods: The Australian Vascular Audit was used to capture lower extremity amputation data in Victoria, Australia, in the 22 months before and after the start of the pandemic. Results: The number of total amputations increased from 1770 pre-pandemic to 1850 during the pandemic, a 4.3% increase. This was largely driven by a statistically significant, 19% increase in major amputations. The number of minor amputations remained relatively similar in the two time periods. Amputations due to tissue loss secondary to arterial insufficiency increased from 474 to 526, an 11% increase, potentially indicating disruptions to revascularisation procedures contributing to the rise in amputations. Elective and emergency surgeries fell by 14% and 18%, respectively, while semi-urgent amputations increased by 32%. Conclusion: This study found an increase in the number of amputations overall and a significant increase in major amputations during the pandemic compared to pre-pandemic times. Tissue loss secondary to arterial insufficiency was an increasingly common indication for amputation that was observed in the pandemic group, indicating that disruption to revascularisation likely contributed to this increase in amputations. These findings can inform and direct future vascular surgery service delivery to prepare for the post-pandemic recovery. Additionally, this study further confirms that patients with chronic diseases are often disproportionately disadvantaged when global crises affect routine provision of healthcare and calls for better systems to be developed that can be used in such crises in the future.

Solar-powered shape-changing origami microfliers.

Using wind to disperse microfliers that fall like seeds and leaves can help automate large-scale sensor deployments. Here, we present battery-free microfliers that can change shape in mid-air to vary their dispersal distance. We designed origami microfliers using bistable leaf-out structures and uncovered an important property: A simple change in the shape of these origami structures causes two dramatically different falling behaviors. When unfolded and flat, the microfliers exhibit a tumbling behavior that increases lateral displacement in the wind. When folded inward, their orientation is stabilized, resulting in a downward descent that is less influenced by wind. To electronically transition between these two shapes, we designed a low-power electromagnetic actuator that produces peak forces of up to 200 millinewtons within 25 milliseconds while powered by solar cells. We fabricated a circuit directly on the folded origami structure that includes a programmable microcontroller, a Bluetooth radio, a solar power-harvesting circuit, a pressure sensor to estimate altitude, and a temperature sensor. Outdoor evaluations show that our 414-milligram origami microfliers were able to electronically change their shape mid-air, travel up to 98 meters in a light breeze, and wirelessly transmit data via Bluetooth up to 60 meters away, using only power collected from the sun.

Association Between Serum MicroRNAs and Abdominal Aortic Aneurysm Diagnosis and Growth.

OBJECTIVE: This study aimed to examine the association between serum microRNAs (miRNAs) and diagnosis and growth of abdominal aortic aneurysm (AAA), and to test their diagnostic and prognostic value. METHODS: The expression levels of 800 miRNA tags were assessed in 108 patients with AAA, 12 age and sex matched healthy controls (HCs), and 12 patients with peripheral artery disease (PAD) using NanoString technology. Findings were assessed in an independent sample of 66 patients with AAA and 29 age and sex matched HCs by reverse transcriptase polymerase chain reaction. AAA growth was assessed by a median of three (interquartile range [IQR] 2, 3) repeat ultrasound scans over a median follow up of 1.1 (IQR 1.0, 2.0) years. The association between the miRNA and AAA diagnosis and growth was examined by regression and linear mixed effects analyses. The diagnostic and prognostic potential of the miRNAs were examined using area under the receiver operator characteristic curve (AUC), net re-classification index (NRI), and Cox hazard analyses. RESULTS: In comparison with HCs, a model combining clinical risk factors, let-7b-5p and miR-548n had an AUC of 98.0% (95% confidence interval [CI] 95.6 - 100.0; p = .003) for diagnosing AAA, which was a significant improvement over clinical risk factors alone (NRI 1.74; 95% CI 1.61 - 1.87; p < .001). Compared with PAD, a model combining clinical risk factors and miR-548n had an AUC of 99.6% (95% CI 98.9 - 100.0, p = .037) for diagnosing AAA, which was a significant improvement over clinical risk factors alone (NRI 1.79, 95% CI 1.68 - 1.91; p < .001). In the longitudinal cohort, none of the miRNAs were able to predict the likelihood of reaching surgical threshold diameter better than clinical risk factors alone. CONCLUSION: Serum let-7b-5p and miR548n significantly improved the ability to diagnose AAA. None of the miRNAs had independent prognosis value in predicting AAA growth.

Artificial Intelligence, Healthcare, Clinical Genomics, and Pharmacogenomics Approaches in Precision Medicine.

Precision medicine has greatly aided in improving health outcomes using earlier diagnosis and better prognosis for chronic diseases. It makes use of clinical data associated with the patient as well as their multi-omics/genomic data to reach a conclusion regarding how a physician should proceed with a specific treatment. Compared to the symptom-driven approach in medicine, precision medicine considers the critical fact that all patients do not react to the same treatment or medication in the same way. When considering the intersection of traditionally distinct arenas of medicine, that is, artificial intelligence, healthcare, clinical genomics, and pharmacogenomics-what ties them together is their impact on the development of precision medicine as a field and how they each contribute to patient-specific, rather than symptom-specific patient outcomes. This study discusses the impact and integration of these different fields in the scope of precision medicine and how they can be used in preventing and predicting acute or chronic diseases. Additionally, this study also discusses the advantages as well as the current challenges associated with artificial intelligence, healthcare, clinical genomics, and pharmacogenomics.

Wind dispersal of battery-free wireless devices.

Plants cover a large fraction of the Earth's land mass despite most species having limited to no mobility. To transport their propagules, many plants have evolved mechanisms to disperse their seeds using the wind1-4. A dandelion seed, for example, has a bristly filament structure that decreases its terminal velocity and helps orient the seed as it wafts to the ground5. Inspired by this, we demonstrate wind dispersal of battery-free wireless sensing devices. Our millimetre-scale devices weigh 30 milligrams and are designed on a flexible substrate using programmable, off-the-shelf parts to enable scalability and flexibility for various sensing and computing applications. The system is powered using lightweight solar cells and an energy harvesting circuit that is robust to low and variable light conditions, and has a backscatter communication link that enables data transmission. To achieve the wide-area dispersal and upright landing that is necessary for solar power harvesting, we developed dandelion-inspired, thin-film porous structures that achieve a terminal velocity of 0.87 ± 0.02 metres per second and aerodynamic stability with a probability of upright landing of over 95%. Our results in outdoor environments demonstrate that these devices can travel 50-100 metres in gentle to moderate breeze. Finally, in natural systems, variance in individual seed morphology causes some seeds to fall closer and others to travel farther. We adopt a similar approach and show how we can modulate the porosity and diameter of the structures to achieve dispersal variation across devices.

Automated Segmentation and Connectivity Analysis for Normal Pressure Hydrocephalus.

Objective and Impact Statement. We propose an automated method of predicting Normal Pressure Hydrocephalus (NPH) from CT scans. A deep convolutional network segments regions of interest from the scans. These regions are then combined with MRI information to predict NPH. To our knowledge, this is the first method which automatically predicts NPH from CT scans and incorporates diffusion tractography information for prediction. Introduction. Due to their low cost and high versatility, CT scans are often used in NPH diagnosis. No well-defined and effective protocol currently exists for analysis of CT scans for NPH. Evans' index, an approximation of the ventricle to brain volume using one 2D image slice, has been proposed but is not robust. The proposed approach is an effective way to quantify regions of interest and offers a computational method for predicting NPH. Methods. We propose a novel method to predict NPH by combining regions of interest segmented from CT scans with connectome data to compute features which capture the impact of enlarged ventricles by excluding fiber tracts passing through these regions. The segmentation and network features are used to train a model for NPH prediction. Results. Our method outperforms the current state-of-the-art by 9 precision points and 29 recall points. Our segmentation model outperforms the current state-of-the-art in segmenting the ventricle, gray-white matter, and subarachnoid space in CT scans. Conclusion. Our experimental results demonstrate that fast and accurate volumetric segmentation of CT brain scans can help improve the NPH diagnosis process, and network properties can increase NPH prediction accuracy.

Closed-loop wearable naloxone injector system.

Overdoses from non-medical use of opioids can lead to hypoxemic/hypercarbic respiratory failure, cardiac arrest, and death when left untreated. Opioid toxicity is readily reversed with naloxone, a competitive antagonist that can restore respiration. However, there remains a critical need for technologies to administer naloxone in the event of unwitnessed overdose events. We report a closed-loop wearable injector system that measures respiration and apneic motion associated with an opioid overdose event using a pair of on-body accelerometers, and administers naloxone subcutaneously upon detection of an apnea. Our proof-of-concept system has been evaluated in two environments: (i) an approved supervised injection facility (SIF) where people self-inject opioids under medical supervision and (ii) a hospital environment where we simulate opioid-induced apneas in healthy participants. In the SIF (n = 25), our system identified breathing rate and post-injection respiratory depression accurately when compared to a respiratory belt. In the hospital, our algorithm identified simulated apneic events and successfully injected participants with 1.2 mg of naloxone. Naloxone delivery was verified by intravenous blood draw post-injection for all participants. A closed-loop naloxone injector system has the potential to complement existing evidence-based harm reduction strategies and, in the absence of bystanders, help make opioid toxicity events functionally witnessed and in turn more likely to be successfully resuscitated.

Reassessing the operative threshold for abdominal aortic aneurysm repair in the context of COVID-19.

OBJECTIVE: The worldwide pandemic involving the novel respiratory syndrome (COVID-19) has forced health care systems to delay elective operations, including abdominal aortic aneurysm (AAA) repair, to conserve resources. This study provides a structured analysis of the decision to delay AAA repair and quantify the potential for harm. METHODS: A decision tree was constructed modeling immediate repair of AAA relative to an initial nonoperative (delayed repair) approach. Risks of COVID-19 contraction and mortality, aneurysm rupture, and operative mortality were considered. A deterministic sensitivity analysis for a range of patient ages (50 to >80), probability of COVID-19 infection (0.01%-30%), aneurysm size (5.5 to >7 cm), and time horizons (3-9 months) was performed. Probabilistic sensitivity analyses were conducted for three representative ages (60, 70, and 80). Analyses were conducted for endovascular aortic aneurysm repair (EVAR) and open surgical repair (OSR). RESULTS: Patients with aneurysms 7 cm or greater demonstrated a higher probability of survival when treated with immediate EVAR or OSR, compared with delayed repair, for patients under 80 years of age. When considering EVAR for aneurysms 5.5 to 6.9 cm, immediate repair had a higher probability of survival except in settings with a high probability of COVID-19 infection (10%-30%) and advanced age (70-85+ years). A nonoperative strategy maximized the probability of survival as patient age or operative risk increased. Probabilistic sensitivity analyses demonstrated that patients with large aneurysms (>7 cm) faced a 5.4% to 7.7% absolute increase in the probability of mortality with a delay of repair of 3 months. Young patients (60-70 years) with aneurysms 6 to 6.9 cm demonstrated an elevated risk of mortality (1.5%-1.9%) with a delay of 3 months. Those with aneurysms 5 to 5.9 cm demonstrated an increased survival with immediate repair in young patients (60); however, this was small in magnitude (0.2%-0.8%). The potential for harm increased as the length of surgical delay increased. For elderly patients requiring OSR, in the context of endemic COVID-19, delay of repair improves the probability of survival. CONCLUSIONS: The decision to delay operative repair of AAA should consider both patient age and local COVID-19 prevalence in addition to aneurysm size. EVAR should be considered when possible due to a reduced risk of harm and lower resource utilization.

Aortic dissection and accelerated aneurysmal degeneration in a patient with giant cell arteritis.

Giant cell arteritis (GCA) is associated with nonatheromatous aortic pathology. Here we present a case in which a 76-year-old woman with a biopsy-proven history of GCA and a previous repair of her ascending aortic aneurysm presents with an acute dissection of a 4-cm aneurysm in the descending thoracic aorta. It was treated using endovascular techniques. This report adds to a growing body of evidence that GCA is a risk factor for aortic dissection and nonatheromatous aortic aneurysms.

Wireless steerable vision for live insects and insect-scale robots.

Vision serves as an essential sensory input for insects but consumes substantial energy resources. The cost to support sensitive photoreceptors has led many insects to develop high visual acuity in only small retinal regions and evolve to move their visual systems independent of their bodies through head motion. By understanding the trade-offs made by insect vision systems in nature, we can design better vision systems for insect-scale robotics in a way that balances energy, computation, and mass. Here, we report a fully wireless, power-autonomous, mechanically steerable vision system that imitates head motion in a form factor small enough to mount on the back of a live beetle or a similarly sized terrestrial robot. Our electronics and actuator weigh 248 milligrams and can steer the camera over 60° based on commands from a smartphone. The camera streams "first person" 160 pixels-by-120 pixels monochrome video at 1 to 5 frames per second (fps) to a Bluetooth radio from up to 120 meters away. We mounted this vision system on two species of freely walking live beetles, demonstrating that triggering image capture using an onboard accelerometer achieves operational times of up to 6 hours with a 10-milliamp hour battery. We also built a small, terrestrial robot (1.6 centimeters by 2 centimeters) that can move at up to 3.5 centimeters per second, support vision, and operate for 63 to 260 minutes. Our results demonstrate that steerable vision can enable object tracking and wide-angle views for 26 to 84 times lower energy than moving the whole robot.

Oral curcumin in elective abdominal aortic aneurysm repair: a multicentre randomized controlled trial.

BACKGROUND: Curcumin, a popular herbal supplement from the plant turmeric, has prevented ischemic reperfusion and toxin-induced injury in many animal studies and a single-centre randomized human trial. We sought to test whether perioperative oral curcumin (compared with placebo) affects the inflammatory response and risk of postrepair complications after elective abdominal aortic aneurysm repair in humans. METHODS: We conducted a parallel-group, randomized, placebo-controlled trial of patients from 10 hospitals in Canada who were scheduled to undergo elective repair of an unruptured abdominal aortic aneurysm (November 2011 to November 2014). Patients in the treatment group received perioperative oral curcumin (2000-mg doses 8 times over 4 d). Patients, health care providers and local research staff were unaware of the treatment assignment. The primary outcomes were median concentrations of 4 bio markers indicating injury and inflammation (postoperative urine interleukin-18 and perioperative rise in serum creatinine, plasma N-terminal pro-B-type natriuretic peptide and plasma high-sensitivity C-reactive protein). RESULTS: Baseline characteristics were similar in the 2 groups (606 patients overall; median age 76 yr). More than 85% of patients in each group took more than 80% of their scheduled capsules. Neither curcumin nor placebo significantly affected any of the 4 biomarkers (p > 0.05 for all comparisons). Regarding the secondary outcomes, there was a higher risk of acute kidney injury with curcumin than with placebo (17% v. 10%, p = 0.01), but no between-group difference in the median length of hospital stay (5 v. 5 days, p > 0.9) or the risk of clinical events (9% v. 9%, p = 0.9). INTERPRETATION: Curcumin had no beneficial effects when used in elective abdominal aortic aneurysm repair. These findings emphasize the importance of testing turmeric and curcumin before espousing their health benefits, as is currently done in the popular media. TRIAL REGISTRATION: ClinicalTrials.gov, no. NCT01225094.

Evaluating the Effectiveness of Internal Iliac Artery Branched Endovascular Stent Grafts.

BACKGROUND: The aim of this study is to describe our institutional experience using iliac branch grafts (IBGs) in aortoiliac aneurysm repair. METHODS: From October 2009 to April 2016, 41 consecutive patients (all men), mean age 71.7 years (range 55-87), underwent IBG implantation. Abdominal aortic aneurysm with common iliac artery involvement (n = 21) or bilateral common iliac artery aneurysms (n = 20) were indications. Computed tomography was used to evaluate patency and postoperative endoleaks within 1 month of implantation and after 1 year. RESULTS: A total of 42 IBGs were deployed in 41 patients successfully. One hundred percent of grafts implanted were patent at 1 month and at annual follow-up. There was 1 mortality at 30 days, due to acute renal failure. Sixteen type II and 1 type Ib endoleaks were found, for which 3 reinterventions were performed and the remainder treated conservatively. Five patients had complications which required reintervention. CONCLUSIONS: IBG placement has excellent short-term outcomes and potential to limit buttock claudication in the treatment of abdominal aortic aneurysms involving the iliac arteries.

A systematic review investigating the association of microRNAs with human abdominal aortic aneurysms.

BACKGROUND AND AIMS: There is increasing interest in identifying novel methods for abdominal aortic aneurysm (AAA) diagnosis. Non-coding RNA molecules such as microRNAs (miRNAs) are stable within the circulation and may serve as biomarkers for AAA. This systematic review aimed to identify miRNAs associated with a diagnosis of human AAA based on currently published original research. METHODS: A systematic search of the MEDLINE and EMBASE databases identified studies assessing miRNA expression in abdominal aortic tissue or circulating blood from human AAA cases compared to non-aneurysmal controls. Data from included studies were extracted to assess methods and results after independent quality assessment by two reviewers. RESULTS: 15 studies were included in this review. 11 studies obtained aortic tissue samples from 195 AAA cases and 104 controls with normal aortas. Nine studies obtained circulating blood samples from 526 AAA cases and 441 controls. miR-21 was differentially expressed in AAA tissue in five separate studies, with four studies reporting upregulation and one reporting downregulation. Seven other miRNAs were differentially expressed in AAA tissue in two separate studies. 15 circulating miRNAs were differentially expressed in two or more separate studies. miR-155 and miR-29b were the only miRNAs differentially expressed in two separate tissue- and blood-based studies. 11 studies offered mechanistic explanations of the role of miRNAs in AAA pathology through exploration of gene targets. Three studies assessed the diagnostic potential of circulating miRNAs with receiver operating characteristic curves. Only one study assessed the prognostic potential of circulating miRNAs in predicting AAA growth. CONCLUSIONS: Several miRNAs have been found to be associated with human AAA. Their utility as AAA biomarkers requires further investigation.

Epigenetics and Peripheral Artery Disease.

The term epigenetics is usually used to describe inheritable changes in gene function which do not involve changes in the DNA sequence. These typically include non-coding RNAs, DNA methylation and histone modifications. Smoking and older age are recognised risk factors for peripheral artery diseases, such as occlusive lower limb artery disease and abdominal aortic aneurysm, and have been implicated in promoting epigenetic changes. This brief review describes studies that have associated epigenetic factors with peripheral artery diseases and investigations which have examined the effect of epigenetic modifications on the outcome of peripheral artery diseases in mouse models. Investigations have largely focused on microRNAs and have identified a number of circulating microRNAs associated with human peripheral artery diseases. Upregulating or antagonising a number of microRNAs has also been reported to limit aortic aneurysm development and hind limb ischemia in mouse models. The importance of DNA methylation and histone modifications in peripheral artery disease has been relatively little studied. Whether circulating microRNAs can be used to assist identification of patients with peripheral artery diseases and be modified in order to improve the outcome of peripheral artery disease will require further investigation.

Risk factors for recurrent primary sclerosing cholangitis after liver transplantation.

BACKGROUND & AIMS: The association between primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD) is well recognised. However, the relationship between IBD and recurrent PSC (rPSC) is less well understood. We assessed the prevalence of rPSC and analysed the factors associated with rPSC post-liver transplantation and its influence on graft and patient survival. METHODS: This is a UK multicentre observational cohort study across six of the seven national liver transplant units. All patients undergoing a first liver transplant for PSC between January 1 1990 and December 31 2010 were included. Prospectively collected liver transplant data was obtained from NHSBT and colitis data was retrospectively collected from individual units. RESULTS: There were 679 (8.8%) first transplants for PSC. 347 patients (61.4%) had IBD, of which 306 (88.2%) had ulcerative colitis (UC). 81 (14.3%) patients developed rPSC and 37 (48.7%) of them developed graft failure from rPSC. Presence of UC post-liver transplant (HR=2.40, 95% CI 1.44-4.02) and younger age (HR=0.78, 95% CI 0.66-0.93) were the only factors significantly associated with rPSC. rPSC was associated with over a 4-fold increase in the risk of death (HR=4.71, 95% CI 3.39, 6.56) with 1, 5, and 10-year graft survival rates of 98%, 84%, and 56% respectively compared to 95%, 88%, and 72% in patients who did not develop rPSC. CONCLUSION: The presence of UC post-liver transplant is associated with a significantly increased risk of rPSC. Furthermore, the presence of rPSC increases the rate of graft failure and death, with higher re-transplantation rates.

Visceral adiposity is not associated with abdominal aortic aneurysm presence and growth.

Previous studies in rodent models and patients suggest that visceral adipose could play a direct role in the development and progression of abdominal aortic aneurysm (AAA). This study aimed to assess the association of visceral adiposity with AAA presence and growth. This study was a case-control investigation of patients that did (n=196) and did not (n=181) have an AAA who presented to The Townsville Hospital vascular clinic between 2003 and 2012. Cases were patients with AAA (infra-renal aortic diameter >30 mm) and controls were patients with intermittent claudication but no AAA (infra-renal aortic diameter <30 mm). All patients underwent computed tomography angiography (CTA). The visceral to total abdominal adipose volume ratio was estimated from CTAs by assessing total and visceral adipose deposits using an imaging software program. Measurements were assessed for reproducibility by repeat assessments on 15 patients. AAA risk factors were recorded at entry. Forty-five cases underwent two CTAs more than 6 months apart to assess AAA expansion. The association of visceral adiposity with AAA presence and growth was examined using logistic regression. Visceral adipose assessment by CTA was highly reproducible (mean coefficient of variation 1.0%). AAA was positively associated with older age and negatively associated with diabetes. The visceral to total abdominal adipose volume ratio was not significantly associated with AAA after adjustment for other risk factors. Patients with a visceral to total abdominal adipose volume ratio in quartile four had a 1.63-fold increased risk of AAA but with wide confidence intervals (95% CI 0.71-3.70; p=0.248). Visceral adiposity was not associated with AAA growth. In conclusion, this study suggests that visceral adiposity is not specifically associated with AAA presence or growth although larger studies are required to confirm these findings.

Thrombus volume is similar in patients with ruptured and intact abdominal aortic aneurysms.

OBJECTIVE: Most abdominal aortic aneurysms (AAAs) contain intraluminal thrombus (ILT), which has been demonstrated to contain proteolytic enzymes and proinflammatory cytokines implicated in AAA progression and rupture. In animal models, anticoagulants have been shown to limit AAA progression. Whether ILT plays a role in AAA rupture is unknown. The aim of this study was to compare the volume of ILT in patients with ruptured and intact AAAs. METHODS: We matched by maximum axial diameter alone, on a 1:2 basis, 28 patients with ruptured AAAs and 56 patients with intact AAAs. Total infrarenal aortic volume and ILT volume were measured from computed tomography angiograms using a previously validated and reproducible semiautomated workstation protocol. Clinical risk factors were also recorded. The Mann-Whitney U test was used to compare ILT volumes between patients with ruptured and intact AAAs. RESULTS: Median (interquartile range [IQR]) maximum AAA diameter (84.0 [77.5-93.9] mm vs 82.6 [77.1-93.3] mm; P = .769) and median (IQR) total AAA volume (372.8 [277.4-486.1] cm(3) vs 358.4 [289.1-563.4] cm(3); P = .977) were similar in patients with ruptured and intact AAAs. Median (IQR) AAA ILT volume was similar in patients with ruptured (152.7 [84.8-252.4] cm(3)) and intact (180.1 [89.9-254.8] cm(3); P = .414) AAAs. CONCLUSIONS: This study suggests that ILT volume is not different in ruptured and intact AAAs.

Body mass index is inversely associated with mortality in patients with peripheral vascular disease.

BACKGROUND: Current guidelines contain no advice on how to manage obesity and underweight in patients with peripheral vascular disease (PVD). OBJECTIVES: The aim of this study was to assess the association of underweight, overweight and obesity with mortality in patients with PVD. PATIENTS AND METHODS: We recruited 1472 patients with a broad range of presentations of PVD. Underweight, overweight and obesity were defined by body mass index (BMI) and associated with mortality using Kaplan Meier and Cox proportional hazard analyses. RESULTS: Survival at 3 years was 37.5, 78.1, 86.8 and 87.0% for patients that were underweight, normal weight, overweight and obese at recruitment, respectively, p<0.001. Patients that were underweight had approximately twice the risk of dying (RR 2.15, 95% CI 1.31-3.55, p=0.003), while patients that were overweight (RR 0.67, 95% CI 0.49-0.91, p=0.011) or obese (RR 0.59, 95% CI 0.41-0.85, p=0.005) had approximately half the risk of dying, after adjustment for other risk factors and using normal weight subjects as the reference group. 823 patients had waist circumference measured at recruitment. Patients with waist circumference in the top quartile had half the risk of dying (RR 0.50, 95% CI 0.26-0.98, p=0.045). In 267 patients we assessed the relationship between BMI and abdominal fat volumes using computed tomography. BMI was highly correlated with both intra-abdominal and subcutaneous fat volumes. CONCLUSIONS: Obesity whether assessed by BMI or central fat deposition is associated with reduced risk of dying in patients with established PVD. Underweight is highly predictive of early mortality in patients with PVD.

The association of visceral adiposity with cardiovascular events in patients with peripheral artery disease.

BACKGROUND: Previous studies have suggested that patients with peripheral artery disease (PAD) suffer from a high incidence of cardiovascular events (CVE). Visceral adiposity has been implicated in promoting CVEs. This study aimed to assess the association of relative visceral adipose volume with incident cardiovascular events in patients with peripheral artery disease. METHODS: This was a prospective cohort study including 260 patients with PAD who presented between 2003 and 2012. Cases were patients with diagnosed PAD including symptomatic lower limb athero-thrombosis and asymptomatic abdominal aortic aneurysm. All patients underwent computed tomography angiography (CTA). Abdominal visceral to total adipose volume ratio (relative visceral adipose volume) was estimated from CTAs using a previously validated workstation protocol. Cardiovascular risk factors were recorded at entry. The association of visceral adiposity with major CVEs (death, non-fatal myocardial infarction or stroke) was examined using Kaplan Meier and Cox proportional hazard analyses. RESULTS: A total of 92 major CVEs were recorded in 76 patients during a median follow-up of 2.8 (IQR 1.2 to 4.8) years, including myocardial infarction (n = 26), stroke (n = 10) and death (n = 56). At 3 years the incidence of major CVEs stratified by relative visceral adipose volume quartiles were 15% [Quartile (Q) 1], 17% (Q2), 11% (Q3) and 15% (Q4) (P = 0.517). Relative visceral adipose volume was not associated with major CVEs after adjustment for other risk factors. CONCLUSION: This study suggests that visceral adiposity does not play a central role in the predisposition for major CVEs in patients with PAD.