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.

Patient Factors Influencing Prescription of Antithrombotic Medication After Lower Limb Endovascular Intervention.

OBJECTIVE: There is significant practice variation in the use of antithrombotic therapy after endovascular intervention for lower limb peripheral arterial disease, with differences in medication choice and duration. Prescriber decision making is complex, and patient factors have been shown to substantially contribute to prescribing variation. To determine the influence of patient factors on antithrombotic prescribing, a discrete choice experiment was distributed to vascular surgeons and trainees across Australia and Aotearoa New Zealand. METHODS: After pilot testing, the discrete choice experiment questionnaire was distributed to 300 vascular surgeons and trainee members of the Australian and New Zealand Society for Vascular Surgery. Multinomial logistic regression models were used to analyse patient factors that had the most influence on decisions to prescribe a second antithrombotic agent, and the preferred choice of antithrombotic (clopidogrel 75 mg daily or rivaroxaban 2.5 mg twice daily) in addition to aspirin 100 mg daily. The odds ratio (OR) with 95% confidence interval (CI) reported preference strength. RESULTS: A total of 44 questionnaires were completed between September and October 2023, reaching the 15% targeted response rate. Prescribing a second antithrombotic was more likely after femoropopliteal stenting compared with angioplasty (OR 1.89, 95% CI 1.20 - 2.13), and in chronic limb threatening ischaemia compared with intermittent claudication (OR 1.58, 95% CI 1.20 - 2.13). Most respondents preferred clopidogrel over rivaroxaban (62%), with over a third of respondents exclusively prescribing clopidogrel. Patients with stents (OR 1.77, 95% CI 1.32 - 2.37) or moderate bleeding risk (OR 1.38, 95% CI 0.97 - 1.84) were more likely to receive clopidogrel than rivaroxaban. CONCLUSION: This study demonstrates that vascular surgeons primarily prioritise antithrombotic prescribing decisions by procedure type. Clopidogrel is more likely to be prescribed than rivaroxaban as a second agent in combination with aspirin, especially after stenting. Knowing these clinician preferences can target implementation strategies towards supporting decision making in subgroups of patients according to individual risk profiles.

The prevalent causes of death in patients with peripheral artery disease undergoing revascularisation or amputation.

OBJECTIVE: Preventing untimely death in patients with peripheral artery disease (PAD) requires a detailed understanding of the predominant causes of death (COD). This literature review aims to describe how short- and long-term COD are reported in patients who had surgery for PAD. METHODS: A literature review was conducted according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines for articles reporting specific causes of mortality in patients who had surgery for all stages of PAD. Articles were included if they reported COD after open surgical or endovascular revascularisation, or major or minor amputation for PAD. Critical appraisals were conducted according to included study types, using the Joanna Briggs Institute tools. RESULTS: Cause of death was reported in 21 publications. Twenty were observational and one was a randomised control trial. Study size ranged from 25 to 10,505 patients. Cardiovascular disease was the most prevalent COD in perioperative periods (42.5% from 13 studies). Long-term follow-up ranged from 1 month and 7 years with 15 studies reporting cardiac related mortality as the most frequent cause of death. However, mortality from neoplasia, respiratory disease (including pneumonia and pulmonary emboli), stroke and sepsis were prevalent. Many studies were low-average quality, with few population-based observational studies. CONCLUSION: Whilst cardiovascular COD are the most prevalent reasons for mortality in patients with PAD, the proportion of patients dying from neoplasia and respiratory disease is high. Improved reporting standards for COD in studies examining PAD are needed.

Infigratinib, a selective FGFR1-3 tyrosine kinase inhibitor, alters dentoalveolar development at high doses.

BACKGROUND: Fibroblast growth factor receptor-3 (FGFR3) gain-of-function mutations are linked to achondroplasia. Infigratinib, a FGFR1-3 tyrosine kinase inhibitor, improves skeletal growth in an achondroplasia mouse model. FGFs and their receptors have critical roles in developing teeth, yet effects of infigratinib on tooth development have not been assessed. Dentoalveolar and craniofacial phenotype of Wistar rats dosed with low (0.1 mg/kg) and high (1.0 mg/kg) dose infigratinib were evaluated using micro-computed tomography, histology, and immunohistochemistry. RESULTS: Mandibular third molars were reduced in size and exhibited aberrant crown and root morphology in 100% of female rats and 80% of male rats at high doses. FGFR3 and FGF18 immunolocalization and extracellular matrix protein expression were unaffected, but cathepsin K (CTSK) was altered by infigratinib. Cranial vault bones exhibited alterations in dimension, volume, and density that were more pronounced in females. In both sexes, interfrontal sutures were significantly more patent with high dose vs vehicle. CONCLUSIONS: High dose infigratinib administered to rats during early stages affects dental and craniofacial development. Changes in CTSK from infigratinib in female rats suggest FGFR roles in bone homeostasis. While dental and craniofacial disruptions are not expected at therapeutic doses, our findings confirm the importance of dental monitoring in clinical studies.

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.

Patient and Geographical Disparities in Functional Outcomes After Major Lower Limb Amputation in Australia.

BACKGROUND: Major lower limb amputations are associated with considerable disability, low quality of life, and poor rates of returning to work, all of which are often attributed to the poor level of functional mobility that amputees experience postoperatively. This study aimed to quantify ambulatory outcomes after major lower limb amputation and identify potential prognostic factors for patients most likely to achieve ambulation and prosthesis use, with the hypothesis that variation in outcomes correlates to age, level of amputation, and place of residence at the time of amputation. METHODS: This retrospective cohort study identified functional outcomes for patients who had lower limb amputations between 2012 and 2020. Patients were identified from the 10th revision of the International Classification of Diseases Australian Modification (ICD-10-AM)-coded state-wide government-maintained hospital administrative data by procedure codes for lower limb amputation. The primary outcomes were ambulation at the time of discharge from acute hospital stay, discharge destination, and prosthesis use. Variables for adjustment included patient age, comorbidity, level of amputation, and place of residence. RESULTS: Three-hundred and seventeen amputations were performed in 269 patients. Most procedures were transtibial amputations (56.4%) and for ischemic/infective indications (84%). Thirty-seven percent of patients were ambulating independently at the time of discharge and 55.9% demonstrated independent mobility with prosthesis at follow-up. Ambulation at the time of discharge predicted patients who were more likely to return home rather than residential or hospital care (odds ratio [OR] 1.8 95%; confidence interval [CI] 1.0-3.2). Patients with transtibial amputation were more likely to achieve prosthesis use than transfemoral (OR 4.4, 95% CI 2.1-9.5), after adjusting for age, comorbidity, and geographical factors. Mobility and prosthesis use was lowest in patients who were older, had transfemoral amputations, and resided in regional or rural areas. CONCLUSIONS: The significant outcome disparities identified in this cohort study highlight the need for targeted quality interventions aimed at improving functional outcomes for patients undergoing major amputation for peripheral artery disease.

Tracheal Stent Buckling and In-stent Stenosis: A Proposed Airway Management Algorithm for Airway Obstruction for Patients With Tracheal Stents.

EMERGENCY AIRWAY management strategies for patients with complications due to tracheobronchial stents are of growing interest to anesthesiologists. Although tracheal stenting increasingly is used to manage tracheobronchial stenosis of both benign and malignant conditions,1-3 official guidelines for the perioperative airway management of patients with tracheobronchial stents in situ are lacking.3 Here, the authors discuss the management of airway obstruction from a tracheal stent strut protrusion and in-stent stenosis in a patient with a self-expanding nitinol tracheal stent in situ. They discuss the airway management strategy employed and outline a pragmatic airway management algorithm for patients with tracheal stents presenting with airway obstruction.

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.

A Qualitative Study Exploring Patient Concerns and Values in Chronic Limb-Threatening Ischemia.

BACKGROUND: Chronic limb-threatening ischemia (CLTI) is the debilitating end stage of peripheral artery disease, causing patients to experience low quality of life and poor health outcomes. It is unknown which aspects of care patients with CLTI value. This pilot qualitative study aims to explore patients' concerns and values related to CLTI treatment, to better inform patient-centered care. METHODS: A qualitative study design was piloted to explore the experiences of patients with CLTI undergoing elective vascular surgery. In-depth, semistructured interviews were recorded preoperatively and 3 mo after discharge. Transcribed interviews were analyzed using content analysis, to derive patient-centered themes. Findings were mapped to a framework of patient-centered care. RESULTS: Twelve interviews from six participants were analyzed. Five themes related to participant experiences of CLTI were identified: treatment and diagnosis, concerns about symptoms, limitations in physical function, social function, and emotional function. Participants expressed how CLTI intruded on all aspects of their lives. Framework analysis demonstrated CLTI patients valued patient-centered care relating to both relational and functional aspects of care. In particular, participants valued supportive and trustworthy care, in addition to integrated, holistic care that recognized the patient in the context of their overall health and life. CONCLUSIONS: Feasibility was demonstrated for both study design and methodology. Data obtained from interviews were sufficiently "rich and thick" in quality and quantity to allow for common themes related to experience and health care values in patients with CLTI to be identified. If confirmed in future studies, these findings will enhance patient-centered care in CLTI.

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.

Incidence, prognostic factors and impact of postoperative delirium after major vascular surgery: A meta-analysis and systematic review.

Although postoperative delirium is a common complication and increases patient care needs, little is known about the predictors and outcomes of delirium in patients having vascular surgery. This review aimed to determine the incidence, prognostic factors and impact of postoperative delirium in vascular surgical patients. MEDLINE and EMBASE were systematically searched for articles published between January 2000 and January 2016 on delirium after vascular surgery. The primary outcome was the incidence of delirium. Secondary outcomes were contributing prognostic factors and impact of delirium. Study quality and risk of bias was assessed using the QUIPS tool for systematic reviews of prognostic studies, and MOOSE guidelines for reviews of observational studies. Quantitative analyses of extracted data were conducted using meta-analysis where possible to determine incidence of delirium and prognostic factors. A qualitative review of outcomes was performed. Fifteen articles were eligible for inclusion. Delirium incidence ranged between 5% and 39%. Meta-analysis found that patients with delirium were older than those without delirium (OR 3.6, p<0.001). Prognostic factors predicting delirium included increased age (OR 1.04, p<0.001), pre-existing cognitive impairment (OR 9.8, p=0.01), hypertension, pre-existing depression and open aortic surgery. Delirious patients remained in hospital 6 days longer ( p<0.001) and had more complications than patients without delirium. Data were limited on the impact of procedure complexity, endovascular compared to open surgery or type of anaesthetic. Postoperative delirium occurs frequently, resulting in major morbidity for vascular patients. Improved quality of prognostic studies may identify modifiable peri-operative factors to improve quality of care for vascular surgical patients.

Prescriber decision-making on antithrombotic therapy after endovascular intervention for peripheral artery disease: a protocol for a discrete choice experiment.

INTRODUCTION: Peripheral artery disease (PAD) is a major risk factor for cardiovascular morbidity and mortality, despite surgical and endovascular treatments. Emerging evidence supports the use of immediate antithrombotic medications after endovascular intervention for PAD, however, there is a lack of consensus regarding choice and duration of antithrombotic therapy. Prescriber decision-making is a complex process, with prior studies demonstrating patient factors can influence variability in antithrombotic therapy for PAD. However, it remains unclear the relative contribution of these factors. This paper describes a planned study that aims to (1) determine the influence of patient factors on clinician preference for antithrombotic therapy following endovascular intervention and (2) compare differences in prescribing preferences between consultant vascular surgeons and trainees. METHODS AND ANALYSIS: This cross-sectional survey will evaluate antithrombotic prescribing choices using a discrete choice experiment (DCE) that has been developed and piloted for this study. A list of attributes and levels was generated using a mixed-methods approach. This included an extensive literature review and semistructured interviews with prescribing clinicians. Following final selection of included attributes, specialised software was used to construct a D-efficient design for the DCE questionnaire. The electronic questionnaire will be administered to vascular trainees and consultant surgeons across Australia. These data will be analysed using multinomial logistic regression, treating the decision to prescribe antithrombotic therapy as a function of both the attributes of the two alternatives, as well as characteristics of the respondent. Latent class analysis will be used to explore heterogeneity of responses. ETHICS AND DISSEMINATION: Ethics approval was obtained from the University of Sydney Human Ethics committee (2023/474). The results of this study will be published in peer-reviewed journals and presented at national vascular surgical conferences. These results will be used to improve understanding how clinicians make prescribing decisions and to inform future strategy to enhance guideline-directed prescribing.