Evaluation of Local Anaesthesia in the endovascular repair of ruptured abdominal aortic aneurysms: a Target trial and Economic evaluation (ELATE)

Research question: How effective and cost-effective is local infiltrative anaesthesia versus general anaesthesia for endovascular repair of ruptured abdominal aortic aneurisms (rAAA)? Background: For people who have surgery for rAAA, outcomes are poor; even after endovascular surgery 40% die within one year. NICE recommend that surgeons consider local anaesthesia for endovascular repair of rAAA. However, no rigorous evidence exists to inform this decision. There is wide variation in the type of anaesthesia used across vascular centres in the UK. An RCT to address this question is likely to be impractical and unethical. Consequently, evidence from observational studies is required. A target trial emulates a hypothetical pragmatic RCT for assessing comparative effectiveness using observational data. Aims and objectives: To evaluate the effectiveness and cost-effectiveness of local versus general anaesthesia for endovascular repair (EVAR) of rAAA. The objectives are: To assess the effectiveness and cost-effectiveness of local versus general anaesthesia for EVAR of rAAA To assess the effectiveness and cost-effectiveness of local versus general anaesthesia in patient subgroups (e.g. sex, frailty) To provide recommendations on the choice of anaesthesia according to patient subgroup Methods: We will provide timely, rigorous evidence on the effectiveness and cost-effectiveness of local versus general anaesthesia for EVAR of rAAA. Our target trial will use observational data from the National Vascular Registry (NVR). It will apply criteria to define the study populations, intervention and comparator strategies and outcomes of direct relevance to clinical decision-making. Criteria will be informed by panels of clinicians and patients/public representatives. Based on advice from patients and clinicians, the primary outcome will be 30-day mortality. Secondary outcomes will include days alive and out of hospital. We will use an instrumental variable analysis based on the approach we used in a previous NIHR-funded study (ESORT). This approach can provide accurate estimates of treatment effectiveness, even when there are unmeasured differences between the intervention and comparator groups. The cost-effectiveness analyses will be based on resource use and mortality data from the NVR linked to Hospital Episode Statistics and mortality data. We will report relative effectiveness and cost-effectiveness according to pre-specified patient subgroups. We will provide recommendations on which mode of anaesthesia is likely to be effective and cost-effective for each subgroup. To help ensure this study generates evidence that directly meets the needs of decision-makers, we will convene panels of clinicians, patient/public representatives, and other stakeholders at the study outset. These groups will help translate results to directly inform clinical decision-making including updates to clinical guidelines for rAAA. Timelines for delivery: Data/ethics applications (pre-start), clinical/patient panels and all stakeholders event (months 0-7); receive data (1-10); prepare and analyse data (1-22); results translation (19-23), papers and final synopsis (21-24). Anticipated impact and translation: Our clinical and patient/public panels and all stakeholder event will help ensure the research is directly relevant to the NHS. Our clinical co-applicants and steering committee will help translate findings to national decision-makers. This study will exemplify how timely input from key stakeholders can help ensure a target trial directly informs clinical practice.