Strand-resolved mutagenicity of DNA damage and repair.

DNA base damage is a major source of oncogenic mutations1. Such damage can produce strand-phased mutation patterns and multiallelic variation through the process of lesion segregation2. Here we exploited these properties to reveal how strand-asymmetric processes, such as replication and transcription, shape DNA damage and repair. Despite distinct mechanisms of leading and lagging strand replication3,4, we observe identical fidelity and damage tolerance for both strands. For small alkylation adducts of DNA, our results support a model in which the same translesion polymerase is recruited on-the-fly to both replication strands, starkly contrasting the strand asymmetric tolerance of bulky UV-induced adducts5. The accumulation of multiple distinct mutations at the site of persistent lesions provides the means to quantify the relative efficiency of repair processes genome wide and at single-base resolution. At multiple scales, we show DNA damage-induced mutations are largely shaped by the influence of DNA accessibility on repair efficiency, rather than gradients of DNA damage. Finally, we reveal specific genomic conditions that can actively drive oncogenic mutagenesis by corrupting the fidelity of nucleotide excision repair. These results provide insight into how strand-asymmetric mechanisms underlie the formation, tolerance and repair of DNA damage, thereby shaping cancer genome evolution.

Convergent somatic mutations in metabolism genes in chronic liver disease.

The progression of chronic liver disease to hepatocellular carcinoma is caused by the acquisition of somatic mutations that affect 20-30 cancer genes1-8. Burdens of somatic mutations are higher and clonal expansions larger in chronic liver disease9-13 than in normal liver13-16, which enables positive selection to shape the genomic landscape9-13. Here we analysed somatic mutations from 1,590 genomes across 34 liver samples, including healthy controls, alcohol-related liver disease and non-alcoholic fatty liver disease. Seven of the 29 patients with liver disease had mutations in FOXO1, the major transcription factor in insulin signalling. These mutations affected a single hotspot within the gene, impairing the insulin-mediated nuclear export of FOXO1. Notably, six of the seven patients with FOXO1S22W hotspot mutations showed convergent evolution, with variants acquired independently by up to nine distinct hepatocyte clones per patient. CIDEB, which regulates lipid droplet metabolism in hepatocytes17-19, and GPAM, which produces storage triacylglycerol from free fatty acids20,21, also had a significant excess of mutations. We again observed frequent convergent evolution: up to fourteen independent clones per patient with CIDEB mutations and up to seven clones per patient with GPAM mutations. Mutations in metabolism genes were distributed across multiple anatomical segments of the liver, increased clone size and were seen in both alcohol-related liver disease and non-alcoholic fatty liver disease, but rarely in hepatocellular carcinoma. Master regulators of metabolic pathways are a frequent target of convergent somatic mutation in alcohol-related and non-alcoholic fatty liver disease.

DNA lesion bypass and the stochastic dynamics of transcription-coupled repair.

DNA base damage is a major source of oncogenic mutations and disruption to gene expression. The stalling of RNA polymerase II (RNAP) at sites of DNA damage and the subsequent triggering of repair processes have major roles in shaping the genome-wide distribution of mutations, clearing barriers to transcription, and minimizing the production of miscoded gene products. Despite its importance for genetic integrity, key mechanistic features of this transcription-coupled repair (TCR) process are controversial or unknown. Here, we exploited a well-powered in vivo mammalian model system to explore the mechanistic properties and parameters of TCR for alkylation damage at fine spatial resolution and with discrimination of the damaged DNA strand. For rigorous interpretation, a generalizable mathematical model of DNA damage and TCR was developed. Fitting experimental data to the model and simulation revealed that RNA polymerases frequently bypass lesions without triggering repair, indicating that small alkylation adducts are unlikely to be an efficient barrier to gene expression. Following a burst of damage, the efficiency of transcription-coupled repair gradually decays through gene bodies with implications for the occurrence and accurate inference of driver mutations in cancer. The reinitation of transcription from the repair site is not a general feature of transcription-coupled repair, and the observed data is consistent with reinitiation never taking place. Collectively, these results reveal how the directional but stochastic activity of TCR shapes the distribution of mutations following DNA damage.

Pervasive lesion segregation shapes cancer genome evolution.

Cancers arise through the acquisition of oncogenic mutations and grow by clonal expansion1,2. Here we reveal that most mutagenic DNA lesions are not resolved into a mutated DNA base pair within a single cell cycle. Instead, DNA lesions segregate, unrepaired, into daughter cells for multiple cell generations, resulting in the chromosome-scale phasing of subsequent mutations. We characterize this process in mutagen-induced mouse liver tumours and show that DNA replication across persisting lesions can produce multiple alternative alleles in successive cell divisions, thereby generating both multiallelic and combinatorial genetic diversity. The phasing of lesions enables accurate measurement of strand-biased repair processes, quantification of oncogenic selection and fine mapping of sister-chromatid-exchange events. Finally, we demonstrate that lesion segregation is a unifying property of exogenous mutagens, including UV light and chemotherapy agents in human cells and tumours, which has profound implications for the evolution and adaptation of cancer genomes.

Somatic mutations and clonal dynamics in healthy and cirrhotic human liver.

The most common causes of chronic liver disease are excess alcohol intake, viral hepatitis and non-alcoholic fatty liver disease, with the clinical spectrum ranging in severity from hepatic inflammation to cirrhosis, liver failure or hepatocellular carcinoma (HCC). The genome of HCC exhibits diverse mutational signatures, resulting in recurrent mutations across more than 30 cancer genes1-7. Stem cells from normal livers have a low mutational burden and limited diversity of signatures8, which suggests that the complexity of HCC arises during the progression to chronic liver disease and subsequent malignant transformation. Here, by sequencing whole genomes of 482 microdissections of 100-500 hepatocytes from 5 normal and 9 cirrhotic livers, we show that cirrhotic liver has a higher mutational burden than normal liver. Although rare in normal hepatocytes, structural variants, including chromothripsis, were prominent in cirrhosis. Driver mutations, such as point mutations and structural variants, affected 1-5% of clones. Clonal expansions of millimetres in diameter occurred in cirrhosis, with clones sequestered by the bands of fibrosis that surround regenerative nodules. Some mutational signatures were universal and equally active in both non-malignant hepatocytes and HCCs; some were substantially more active in HCCs than chronic liver disease; and others-arising from exogenous exposures-were present in a subset of patients. The activity of exogenous signatures between adjacent cirrhotic nodules varied by up to tenfold within each patient, as a result of clone-specific and microenvironmental forces. Synchronous HCCs exhibited the same mutational signatures as background cirrhotic liver, but with higher burden. Somatic mutations chronicle the exposures, toxicity, regeneration and clonal structure of liver tissue as it progresses from health to disease.

Sex, Endothelial Cell Functions, and Peripheral Artery Disease.

Peripheral artery disease (PAD) is caused by blocked arteries due to atherosclerosis and/or thrombosis which reduce blood flow to the lower limbs. It results in major morbidity, including ischemic limb, claudication, and amputation, with patients also suffering a heightened risk of heart attack, stroke, and death. Recent studies suggest women have a higher prevalence of PAD than men, and with worse outcomes after intervention. In addition to a potential unconscious bias faced by women with PAD in the health system, with underdiagnosis, and lower rates of guideline-based therapy, fundamental biological differences between men and women may be important. In this review, we highlight sexual dimorphisms in endothelial cell functions and how they may impact PAD pathophysiology in women. Understanding sex-specific mechanisms in PAD is essential for the development of new therapies and personalized care for patients with PAD.

Understanding the Role and Value of Process Quality Indicators in Older Vascular Surgery Inpatients.

BACKGROUND: Despite the development of geriatrics surgery process quality indicators (QIs), few studies have reported on these QIs in routine surgical practice. Even less is known about the links between these QIs and clinical outcomes, and patient characteristics. We aimed to measure geriatrics surgery process QIs, and investigate the association between process QIs and outcomes, and QIs and patient characteristics, in hospitalized older vascular surgery patients. METHODS: This was a prospective cohort study of 150 consecutive patients aged ≥ 65 years admitted to a tertiary vascular surgery unit. Occurrence of geriatrics surgery process QIs as part of routine vascular surgery care was measured. Associations between QIs and high-risk patient characteristics, and QIs and clinical outcomes were assessed using clustered heatmaps. RESULTS: QI occurrence rate varied substantially from 2% to 93%. Some QIs, such as cognition and delirium screening, documented treatment preferences, and geriatrician consultation were infrequent and clustered with high-risk patient characteristcs. There were two major process-outcome clusters: (a) multidisciplinary consultations, communication and screening-based process QIs with multiple adverse outcomes, and (b) documentation and prescribing-related QIs with fewer adverse outcomes. CONCLUSIONS: Clustering patterns of process QIs with clinical outcomes are complex, and there is a differential occurrence of QIs by patient characteristics. Prospective intervention studies that report on implemented QIs, outcomes and patient characteristics are needed to better understand the causal pathways between process QIs and outcomes, and to help prioritize targets for quality improvement in the care of older surgical patients.

Multiple Peri-Operative Complications are Associated with Reduced Long Term Amputation Free Survival Following Revascularisation for Lower Limb Peripheral Artery Disease: A Population Based Linked Data Study.

OBJECTIVE: To determine, in a population based linked data study, the relationship between peri-operative multiple complications and longer term outcomes, specifically the combined outcome of two year amputation or death, after lower limb revascularisation for peripheral artery disease (PAD). METHODS: State wide health administrative data and death records were probabilistically linked for all patients who had lower limb artery surgery between 2010 and 2012 in New South Wales, Australia. Multivariable Cox regression modelled the impact of medical and surgical complications on the combined outcome of amputation or death two years after discharge. RESULTS: Open surgery was performed on 3004 patients (26.7%), and endovascular on 8263 (73.3%). Of the 10 971 patients discharged alive, 3747 (34.1%) experienced at least one complication, and 2113 (19.3%) had multiple complications. Older patients, those with high comorbidity scores, or those with chronic limb threatening ischaemia were at increased risk of multiple complications. After adjusting for procedure type, patients with multiple complications experienced more than three times the hazard ratio (HR) of amputation or death two years after the procedure than those without complications (adjusted HR 3.4, 95% confidence interval 3.1-3.7), and increasing complications progressively multiplied the risk. In particular, non-surgical complications such as stroke, acute renal failure, delirium, and cardiac events were associated with the highest rates of two year amputation or death. CONCLUSION: Multiple complications after surgery for lower limb PAD carried a compounding risk of reduced long term amputation free survival. Patients experiencing at least one complication form a high risk group that requires increased attention to prevent the potential development of further complications.

Optoacoustics delineates murine breast cancer models displaying angiogenesis and vascular mimicry.

BACKGROUND: Optoacoustic tomography (OT) of breast tumour oxygenation is a promising new technique, currently in clinical trials, which may help to determine disease stage and therapeutic response. However, the ability of OT to distinguish breast tumours displaying different vascular characteristics has yet to be established. The aim of the study is to prove OT as a sensitive technique for differentiating breast tumour models with manifestly different vasculatures. METHODS: Multispectral OT (MSOT) was performed in oestrogen-dependent (MCF-7) and oestrogen-independent (MDA-MB-231) orthotopic breast cancer xenografts. Total haemoglobin (THb) and oxygen saturation (SO2MSOT) were calculated. Pathological and biochemical evaluation of the tumour vascular phenotype was performed for validation. RESULTS: MCF-7 tumours show SO2MSOT similar to healthy tissue in both rim and core, despite significantly lower THb in the core. MDA-MB-231 tumours show markedly lower SO2MSOT with a significant rim-core disparity. Ex vivo analysis revealed that MCF-7 tumours contain fewer blood vessels (CD31+) that are more mature (CD31+/aSMA+) than MDA-MB-231. MCF-7 presented higher levels of stromal VEGF and iNOS, with increased NO serum levels. The vasculogenic process observed in MCF-7 was consistent with angiogenesis, while MDA-MB-231 appeared to rely more on vascular mimicry. CONCLUSIONS: OT is sensitive to differences in the vascular phenotypes of our breast cancer models.

Mutational landscape of a chemically-induced mouse model of liver cancer.

BACKGROUND & AIMS: Carcinogen-induced mouse models of liver cancer are used extensively to study the pathogenesis of the disease and are critical for validating candidate therapeutics. These models can recapitulate molecular and histological features of human disease. However, it is not known if the genomic alterations driving these mouse tumour genomes are comparable to those found in human tumours. Herein, we provide a detailed genomic characterisation of tumours from a commonly used mouse model of hepatocellular carcinoma (HCC). METHODS: We analysed whole exome sequences of liver tumours arising in mice exposed to diethylnitrosamine (DEN). Mutational signatures were compared between liver tumours from DEN-treated and untreated mice, and human HCCs. RESULTS: DEN-initiated tumours had a high, uniform number of somatic single nucleotide variants (SNVs), with few insertions, deletions or copy number alterations, consistent with the known genotoxic action of DEN. Exposure of hepatocytes to DEN left a reproducible mutational imprint in resulting tumour exomes which we could computationally reconstruct using six known COSMIC mutational signatures. The tumours carried a high diversity of low-incidence, non-synonymous point mutations in many oncogenes and tumour suppressors, reflecting the stochastic introduction of SNVs into the hepatocyte genome by the carcinogen. We identified four recurrently mutated genes that were putative oncogenic drivers of HCC in this model. Every neoplasm carried activating hotspot mutations either in codon 61 of Hras, in codon 584 of Braf or in codon 254 of Egfr. Truncating mutations of Apc occurred in 21% of neoplasms, which were exclusively carcinomas supporting a role for deregulation of Wnt/ß-catenin signalling in cancer progression. CONCLUSIONS: Our study provides detailed insight into the mutational landscape of tumours arising in a commonly used carcinogen model of HCC, facilitating the future use of this model to better understand the human disease. LAY SUMMARY: Mouse models are widely used to study the biology of cancer and to test potential therapies. Herein, we have described the mutational landscape of tumours arising in a carcinogen-induced mouse model of liver cancer. Since cancer is a disease caused by genomic alterations, information about the patterns and types of mutations in the tumours in this mouse model should facilitate its use to study human liver cancer.

Single-mitosis dissection of acute and chronic DNA mutagenesis and repair.

How chronic mutational processes and punctuated bursts of DNA damage drive evolution of the cancer genome is poorly understood. Here, we demonstrate a strategy to disentangle and quantify distinct mechanisms underlying genome evolution in single cells, during single mitoses and at single-strand resolution. To distinguish between chronic (reactive oxygen species (ROS)) and acute (ultraviolet light (UV)) mutagenesis, we microfluidically separate pairs of sister cells from the first mitosis following burst UV damage. Strikingly, UV mutations manifest as sister-specific events, revealing mirror-image mutation phasing genome-wide. In contrast, ROS mutagenesis in transcribed regions is reduced strand agnostically. Successive rounds of genome replication over persisting UV damage drives multiallelic variation at CC dinucleotides. Finally, we show that mutation phasing can be resolved to single strands across the entire genome of liver tumors from F1 mice. This strategy can be broadly used to distinguish the contributions of overlapping cancer relevant mutational processes.

Cancer Evolution: A Multifaceted Affair.

Cancer cells adapt and survive through the acquisition and selection of molecular modifications. This process defines cancer evolution. Building on a theoretical framework based on heritable genetic changes has provided insights into the mechanisms supporting cancer evolution. However, cancer hallmarks also emerge via heritable nongenetic mechanisms, including epigenetic and chromatin topological changes, and interactions between tumor cells and the tumor microenvironment. Recent findings on tumor evolutionary mechanisms draw a multifaceted picture where heterogeneous forces interact and influence each other while shaping tumor progression. A comprehensive characterization of the cancer evolutionary toolkit is required to improve personalized medicine and biomarker discovery. SIGNIFICANCE: Tumor evolution is fueled by multiple enabling mechanisms. Importantly, genetic instability, epigenetic reprogramming, and interactions with the tumor microenvironment are neither alternative nor independent evolutionary mechanisms. As demonstrated by findings highlighted in this perspective, experimental and theoretical approaches must account for multiple evolutionary mechanisms and their interactions to ultimately understand, predict, and steer tumor evolution.

The artificial intelligence-based model ANORAK improves histopathological grading of lung adenocarcinoma.

The introduction of the International Association for the Study of Lung Cancer grading system has furthered interest in histopathological grading for risk stratification in lung adenocarcinoma. Complex morphology and high intratumoral heterogeneity present challenges to pathologists, prompting the development of artificial intelligence (AI) methods. Here we developed ANORAK (pyrAmid pooliNg crOss stReam Attention networK), encoding multiresolution inputs with an attention mechanism, to delineate growth patterns from hematoxylin and eosin-stained slides. In 1,372 lung adenocarcinomas across four independent cohorts, AI-based grading was prognostic of disease-free survival, and further assisted pathologists by consistently improving prognostication in stage I tumors. Tumors with discrepant patterns between AI and pathologists had notably higher intratumoral heterogeneity. Furthermore, ANORAK facilitates the morphological and spatial assessment of the acinar pattern, capturing acinus variations with pattern transition. Collectively, our AI method enabled the precision quantification and morphology investigation of growth patterns, reflecting intratumoral histological transitions in lung adenocarcinoma.

The experience of hospital care for older surgical patients and their carers: A mixed-methods study.

OBJECTIVE: A growing proportion of older adults are undergoing surgery, but there is a paucity of patient and carer experience research in this group. This study investigated the experience of hospital care in an older vascular surgery population for patients and their carers. METHODS: This was a mixed-methods convergent design, including simultaneous collection of quantitative and qualitative research strands by combining open-ended questions with rating scales in a questionnaire. Recently hospitalised vascular surgery patients aged ≥65 years at a major teaching hospital were recruited. Carers were also approached to participate. RESULTS: Forty-seven patients (mean age 77 years, 77% male, 20% with a Clinical Frailty Scale score >4) and nine carers participated. The majority of patients reported that their views were listened to (n = 42, 89%), they were kept informed (n = 39, 83%), and were asked about their pain (n = 37, 79%). Among carers, seven reported their views were listened to and that they were kept informed. Thematic analysis of patients' and carers' responses to open-ended questions about their experience of hospital care revealed four themes in terms of what mattered to them: fundamental care including hygiene and nutrition, comfort of the hospital environment such as sleep and meals, being informed and involved in health-care decision-making, and treating pain and deconditioning to help recovery. CONCLUSIONS: Older adults admitted to hospital for vascular surgery and their carers, valued highly the care that met both their fundamental needs and facilitated shared decisions for care and recovery. These priorities can be addressed through Age-Friendly Health System initiatives.

Optimising Medications in Older Vascular Surgery Patients Through Geriatric Co-management.

BACKGROUND: Prescribing of potentially inappropriate medications and under-prescribing of guideline-recommended medications for cardiovascular risk modification have both been associated with negative outcomes in older adults. Hospitalisation represents an important opportunity to optimise medication use and may be achieved through geriatrician-led interventions. OBJECTIVE: We aimed to evaluate whether implementation of a novel model of care called Geriatric Comanagement of older Vascular (GeriCO-V) surgery patients is associated with improvements in medication prescribing. METHODS: We used a prospective pre-post study design. The intervention was a geriatric co-management model, where a geriatrician delivered comprehensive geriatric assessment-based interventions including a routine medication review. We included consecutively admitted patients to the vascular surgery unit at a tertiary academic centre aged ≥ 65 years with an expected length of stay of ≥ 2 days and who were discharged from hospital. Outcomes of interest were the prevalence of at least one potentially inappropriate medication as defined by the Beers Criteria at admission and discharge, and rates of cessation of at least one potentially inappropriate medication present on admission. In the subgroup of patients with peripheral arterial disease, the prevalence of guideline-recommended medications on discharge was determined. RESULTS: There were 137 patients in the pre-intervention group (median [interquartile range] age: 80.0 [74.0-85.0] years, 83 [60.6%] with peripheral arterial disease) and 132 patients in the post-intervention group (median [interquartile range] age: 79.0 (73.0-84.0) years, 75 [56.8%] with peripheral arterial disease). There was no change in the prevalence of potentially inappropriate medication use from admission to discharge in either group (pre-intervention: 74.5% on admission vs 75.2% on discharge; post-intervention: 72.0% vs 72.7%, p = 0.65). Forty-five percent of pre-intervention group patients had at least one potentially inappropriate medication present on admission ceased, compared with 36% of post-intervention group patients (p = 0.11). A higher number of patients with peripheral arterial disease in the post-intervention group were discharged on antiplatelet agent therapy (63 [84.0%] vs 53 [63.9%], p = 0.004) and lipid-lowering therapy (58 [77.3%] vs 55 [66.3%], p = 0.12). CONCLUSIONS: Geriatric co-management was associated with an improvement in guideline-recommended antiplatelet agent prescribing aimed at cardiovascular risk modification for older vascular surgery patients. The prevalence of potentially inappropriate medications was high in this population, and was not reduced with geriatric co-management.

Timing of minor and major amputation in patients with diabetes-related foot ulceration admitted to two public tertiary referral hospitals in Australia.

BACKGROUND: There is limited information regarding the number of patients with diabetes-related foot ulceration (DFU) who receive minor or major amputation, and how quickly these amputations occur. This study aimed to identify the incidence of index minor and major amputation among inpatients with DFU over 4 years, and where amputation occurred during the patient's index DFU-related admission, investigate prognostic factors. METHODS: The incidence of index minor and major amputation, and the admission sequence during which amputation occurred were identified from DFU-related admissions to two public hospitals during 2014-2018. Where minor or major amputation occurred during the patient's index DFU-related admission, prognostic factors were investigated using logistic regression. RESULTS: DFU-related hospital admissions were required by 564 patients. The incidence of minor amputation over 4 years was 34% (n = 193). The incidence of minor amputation during the patient's index DFU-related admission was 28% (n = 155), which was associated with requiring revascularisation (odds ratio [OR] 2.33, 95% CI 1.53-3.55, P < 0.001). The incidence of major amputation over 4 years was 8% (n = 45). The incidence of major amputation during the patient's index DFU-related admission was 6% (n = 31), which was associated with having more comorbidities (OR 1.58, 95% CI 1.10-2.26, P = 0.01) and receiving care for a mental health condition (OR 3.85, 95% CI 1.48-10.01, P = 0.006). CONCLUSION: Most amputations occurred during the patient's index DFU-related hospital admission. Major amputation during a patient's index admission was associated with more comorbidities and mental health conditions.

Geriatric Comanagement of Older Vascular Surgery Inpatients Reduces Hospital-Acquired Geriatric Syndromes.

OBJECTIVE: This study evaluates the impact of a novel model of care called Geriatric Comanagement of Older Vascular surgery inpatients on clinical outcomes. DESIGN, SETTING, AND PARTICIPANTS: A pre-post study of geriatric comanagement, comparing prospectively recruited preintervention (February-October 2019) and prospectively recruited postintervention (January-December 2020) cohorts. Consecutively admitted vascular surgery patients age ≥65 years at a tertiary academic hospital in Concord and with an expected length of stay (LOS) greater than 2 days were recruited. INTERVENTION: A comanagement model where a geriatrician was embedded within the vascular surgery team and delivered proactive comprehensive geriatric assessment based interventions. METHODS: Primary outcomes of incidence of hospital-acquired geriatric syndromes, delirium, and LOS were compared between groups using univariable and multivariable logistic regression analyses. Prespecified subgroup analysis was performed by frailty status. RESULTS: There were 150 patients in the preintervention group and 152 patients in the postintervention group. The postintervention group were more frail [66 (43.4%) vs 45 (30.0%)], urgently admitted [72 (47.4%) vs 56 (37.3%)], and nonoperatively managed [52 (34.2%) vs 33 (22.0%)]. These differences were attributed to the coronavirus disease 2019 pandemic during the postintervention phase. The postintervention group had fewer hospital-acquired geriatric syndromes [74 (48.7%) vs 97 (64.7%); P = .005] and reduced incident delirium [5 (3.3%) vs 15 (10.0%); P = .02], in unadjusted and adjusted analyses. Cardiac [8 (5.3%) vs 30 (20.0%); P < .001] and infective complications [4 (2.6%) vs 12 (8.0%); P = .04] were also fewer. LOS was unchanged. Frail patients in the postintervention group experienced significantly fewer geriatric syndromes including delirium. CONCLUSIONS AND IMPLICATIONS: This is the first prospective study of inpatient geriatric comanagement for older vascular surgery patients. Reductions in hospital-acquired geriatric syndromes including delirium, and cardiac and infective complications were observed after implementing geriatric comanagement. These benefits were also demonstrated in the frail subgroup.

Coagulation factor V is a T-cell inhibitor expressed by leukocytes in COVID-19.

Clotting Factor V (FV) is primarily synthesized in the liver and when cleaved by thrombin forms pro-coagulant Factor Va (FVa). Using whole blood RNAseq and scRNAseq of peripheral blood mononuclear cells, we find that FV mRNA is expressed in leukocytes, and identify neutrophils, monocytes, and T regulatory cells as sources of increased FV in hospitalized patients with COVID-19. Proteomic analysis confirms increased FV in circulating neutrophils in severe COVID-19, and immunofluorescence microscopy identifies FV in lung-infiltrating leukocytes in COVID-19 lung disease. Increased leukocyte FV expression in severe disease correlates with T-cell lymphopenia. Both plasma-derived and a cleavage resistant recombinant FV, but not thrombin cleaved FVa, suppress T-cell proliferation in vitro. Anticoagulants that reduce FV conversion to FVa, including heparin, may have the unintended consequence of suppressing the adaptive immune system.

Frail patients having vascular surgery during the early COVID-19 pandemic experienced high rates of adverse perioperative events and amputation.

BACKGROUND: Frailty predicts adverse perioperative outcomes and increased mortality in patients having vascular surgery. Frailty assessment is a potential tool to inform resource allocation, and shared decision-making about vascular surgery in the resource constrained COVID-19 pandemic environment. This cohort study describes the prevalence of frailty in patients having vascular surgery and the association between frailty, mortality and perioperative outcomes. METHODS: The COVID-19 Vascular Service in Australia (COVER-AU) prospective cohort study evaluates 30-day and six-month outcomes for consecutive patients having vascular surgery in 11 Australian vascular units, March-July 2020. The primary outcome was mortality, with secondary outcomes procedure-related outcomes and hospital utilization. Frailty was assessed using the nine-point visual Clinical Frailty Score, scores of 5 or more considered frail. RESULTS: Of the 917 patients enrolled, 203 were frail (22.1%). The 30 day and 6 month mortality was 2.0% (n = 20) and 5.9% (n = 35) respectively with no significant difference between frail and non-frail patients (OR 1.68, 95%CI 0.79-3.54). However, frail patients stayed longer in hospital, had more perioperative complications, and were more likely to be readmitted or have a reoperation when compared to non-frail patients. At 6 months, frail patients had twice the odds of major amputation compared to non-frail patients, after adjustment (OR 2.01; 95% CI 1.17-3.78), driven by a high rate of amputation during the period of reduced surgical activity. CONCLUSION: Our findings highlight that older, frail patients, experience potentially preventable adverse outcomes and there is a need for targeted interventions to optimize care, especially in times of healthcare stress.

Variation in treatment and outcomes for patients with chronic limb-threatening ischaemia in New South Wales, Australia.

BACKGROUND: Chronic limb-threatening ischaemia (CLTI) carries significant amputation and mortality risks. Australian population-based outcomes for CLTI are inadequately known. This study aimed to distinguish factors associated with outcomes in the first 2 years after CLTI surgery. METHODS: By linking routinely collected health administrative and mortality data from New South Wales, this population-based cohort study identified patients with ischaemic rest pain, gangrene or ulceration undergoing vascular surgery in public hospitals between 2010 and 2012. The primary outcome was 2-year amputation-free survival (AFS), and secondary outcomes included readmission and reoperation rates. Multivariable regression analysis identified prognostic factors adjusted for patient, hospital and geographic factors. RESULTS: Primary CLTI surgery was performed on 4898 patients. Almost half the cohort had minor amputations without concurrent revascularization (2398, 49%), and the remaining patients had open (652, 13%) or endovascular (1848, 38%) surgery. At 2-years, the AFS rate was 72%. Significant disparity was seen between age groups, with the 2-year AFS 71% in patients aged 75 years or older, compared to 95% in patients aged less than 75 years (P < 0.001). Place of residence or hospital training status did not significantly influence AFS or readmission, but non-training hospitals had higher rates of reoperation. CONCLUSION: This population-based cohort study demonstrated variable outcomes for patients with CLTI, particularly with respect to older age, admission acuity and comorbidity. Results may guide service improvements however further research is needed into how population-wide health initiatives can address age-related disparities in CLTI.