Title: A Risk-adjusted and Anatomically Stratified Cohort Comparison Study of Open Surgery, Endovascular Techniques and Medical Management for Juxtarenal Aortic Aneurysms: The UK COMplex AneurySm Study (UK-COMPASS)
Funder: Department of Health and Social Care

Abstract: Study design: Empirical cohort comparison of different strategies for managing juxtarenal AAA, with long-term follow-up. Confounding: Strategies to deal with indication and risk biases: 1)Stratification of operative risk 2)Stratification of anatomical complexity 3)appropriate statistical methods of correction. Setting: Secondary care, all AAA centres in England, linked to the NVR and HES. Population: All patients undergoing elective repair of a juxtarenal AAA in England; and patients with juxtarenal AAA 55 mm or larger in size under medical management. Health technology: OSR, fEVAR, off-label standard EVAR and medical management with deferral of surgery. Outcome measures: Primary endpoints: Death (including perioperative mortality, all-cause mortality and aneurysm-related mortality). Secondary endpoints: Paraplegia, postoperative morbidity, secondary intervention, procedure specific complications including target vessel loss, renal dysfunction including dialysis. Economic measures: Procedure cost including implants and consumables, intensive care usage, length of hospital stay, NHS follow-up costs, use of non-NHS resource. Patient reported measures: Generic and specific Quality of Life scores (EQ-5D 5SL,A-DQoL,A-SRQ,A-TSQ,treatment satisfaction). Material: Majority of the data for the proposed study are well documented in routinely collected datasets from the NVR and HES. Imaging reports and scans will be retrieved via NHS PACS IEP. HR QoL data, wider resource use data and data regarding patients in the medical management arm will be directly collected from participating hospitals and patients. Study dataset (provisional) and the source of each data point are clarified in an attachment. Sample Size: Analyses of surgical interventions will be population based, including all patients undergoing treatment of juxtarenal AAA in England, identified through routinely collected data. Based on NVR 2013-15 reports, we estimate to capture at least 2000 patients in a two-year recruitment. An estimated 300 medical management (operation-deferred) patients will be recruited from hospitals over 4 years. Health Economic analysis: A detailed economic analysis will be undertaken of NHS and wider costs to discern the comparative Incremental Cost Effectiveness Ratios between different management strategies. In line with HTA TAR recommendation, a short-term and a long-term model will be developed with incorporation of the clinical efficacy data developed by the study. Feasibility: A pilot study was completed on a multicentre series. The proposal is a scaled-up version of the same principles to cover all of England. Logistics of data retrieval, regulatory aspects of data handling, data linkage and image retrieval & corelab analysis have been considered thoroughly. Study Duration: 66 m Project timetable: Work start in Jan 17. Regulatory approvals by Jun 17, test data retrieval. Data accrual from routine data will be steady for 24 m, follow-up of 5 years, followed by six months for analysis and write-up. Expertise in team: This is a collaborative proposal with the NVR and PHE, including applicants with expertise in health economics, statistics, PACS retrieval, clinical trials unit, health technology assessment, corelab, PPI, public health policy and clinical expertise.

Lay abstract: Abdominal aortic aneurysm is a common condition where the aorta, which is the main artery that begins at the heart and travels down the torso, begins to bulge and expand at a portion just below the chest, above the level of the navel. In the usual course of events, the bulge expands slowly over many years and can eventually burst. This results in major internal blood loss often resulting in death and when an emergency life saving operation is possible, they have high failure rate. Although the risk of aneurysm rupture is generally low, it starts to increase if the aneurysm exceeds a certain size. A planned operation can be performed to repair the bulging section of aorta to prevent a burst aneurysm. However, not all abdominal aortic aneurysms are equal and technical aspects of aneurysm repair depends upon their location in relation to important branch arteries of the aorta. Over a quarter of aneurysms are classed as juxtarenal aneurysms because they are too close to the arterial branches supplying blood to the kidneys. These aneurysms require more extensive and more complex operations. There are different ways of managing such complex aneurysms and doctors are unsure which method is better. The open repair method is the tried and trusted method, known to be durable and lasts for the rest of most patients’ lives. However, it is quite a serious operation which generally involves a longer stay in hospital and a higher chance of dying within 30 days of the operation when compared to alternative methods called endovascular techniques, of which Fenestrated Endovascular Aneurysm Repair (fEVAR) is the most established method. In a number of patients with juxtarenal aneurysms, doctors are judiciously using standard endovascular repair (Off-label EVAR), a less complex technique that is originally intended for use in less complex aneurysms. Endovascular methods are less of a strain on the patient’s body which results in a shorter recovery time and a better chance of surviving the operation. The downside of this is that it is more common for there to be problems following endovascular repairs that may require further small procedures to correct them. In some cases, patients are not considered fit enough for the open repair operation as it may be too much of a strain on their body and always requires a general anaesthetic. For these patients, doctors find fEVAR or off-label EVAR quite attractive. In a proportion of patients no operation may be considered to be in their best interest. This study is proposed to examine how these different treatment methods compare in terms of clinical benefit and utilisation of valuable NHS resources. We also like to establish if particular patient features will give better results with one type of operation than the other. We intend to include in this study, all patients undergoing juxtarenal aneurysm treatment in England during a period of 2 years and collect 5 year follow-up. We plan to make use of data that is routinely collected for NHS use and for compulsory clinical quality checks. We intend to examine the scans performed as a course of normal patient treatment in order to accurately identify patients having a juxtarenal aneurysm repair. Available data will be analysed not only to compare the safety and effectiveness of different management strategies, but also to see if a particular strategy is better suited for particular features so that patients can be offered bespoke treatment strategies.

Research activity codes: 6.4 SURGERY;7.3 MANAGEMENT AND DECISION MAKING
Health categories: CARDIOVASCULAR