NExT ERA: National Expertise Based Trial of Elective Repair of Abdominal Aortic Aneurysms: A Pilot Study

Overview

Objectives. To study the feasibility of an expertise-based randomized controlled trial (RCT) testing the role of traditional surgery (OPEN) versus endovascular repair (EVAR) for abdominal aortic aneurysms (AAA). Study design. We will conduct an expertise-based RCT comparing OPEN to EVAR of non-urgent abdominal aortic aneurysms in patients referred to vascular surgeons practicing at Hamilton Health Sciences, to determine the rate of death and other complications. Quality of life and status at 6 months will also be recorded. The ultimate goal is to determine the feasibility of conducting a pragmatic expertise-based RCT and to inform a future larger study at a national level.

Background. The prevalence in individuals over 65 years of age is 6% (95% Confidence Interval \[CI\] 5 - 6)(1-4)in men and 1% (95% CI 1 - 2) in women.(5) AAA confers a risk of spontaneous rupture and death: the in-hospital mortality rate of ruptured aneurysms in Ontario was estimated at 40.8%.(6) Prevention of spontaneous rupture is the rationale for surgical intervention. Evidence has established that elective open surgery for AAAs \> 5.5cm increases survival(7), but the 30-day perioperative mortality for elective open repair of AAA can be as high as 8%.(8-17) Phase I and II trials have found that endovascular repair is a 'viable and effective treatment' for AAA disease (18;19); the theoretical benefits include avoidance of laparotomy and no aortic clamping. The results of RCTs (DREAM and EVAR-1)(20;21) have left unanswered the indications for endovascular repair compared with open surgery because of problems with definition of outcomes, lack of statistical power, and surgical expertise (surgeons needed to have done at least 20 surgeries with or without supervision). The only studies addressing the issue of expertise in this field suggests that 60 EVAR need to be done to achieve less than 10% complications (22), and a time interval of less than 10 days between procedures is important to maintain competence and reduce complications.(23) In addition the two RCTs used a conventional design and we have reported that this has intrinsic pitfalls. We argued that in surgery, particularly when a new technique is studied, another approach should be used: the expertise based RCT.(24) Conventional RCTs typically randomize participants to one of two interventions (A or B) and the same clinician give intervention A to some participants and B to others. The expertise based randomized controlled trial, randomizes participants to clinicians with expertise in intervention A or clinicians with expertise in intervention B, and the clinicians perform only the procedure for which they have expertise. Study Design/Participants We will conduct an expertise based RCT comparing open repair with EVAR repair of elective infrarenal AAAs. This is a pilot to determine the feasibility of a large pragmatic expertise based RCT of open versus EVAR repair. We will consider all patients with an AAA determined to require non-urgent repair after assessment by one of the participating surgeons. The second inclusion criterion is that the blinded measurement team must deem a patient to fulfill the anatomic eligibility criteria. Location of Investigation This pilot study will be conducted at a single institution: Hamilton Health Sciences, Hamilton General Hospital. This centre will serve as the coordinating site for the future multicentre randomized controlled trial, and based on the high volume practices of the surgeons at the Hamilton General Hospital, will likely provide the largest pool of eligible patients. Protocols and standard operating procedures for a single site will be developed for this pilot, which will become standards for the larger trial. The decision to use a single centre for this pilot study is based in the high expected surgical volume that makes our recruitment rate realistic, in addition to the cost savings of conducting a trial close to investigators and surrounded by known infrastructure. Patient Recruitment Once a patient is deemed eligible, the study nurse will provide the patient with details of the study protocol and explanation of goals of the investigation, and obtain informed consent. Randomization and Allocation The study nurse will be contacted by the surgeons' offices to screen all patients referred to participating vascular surgeons on the first visit to the office and submit a standardized electronic form accessible on a secure, encrypted website. This will document baseline demographics for referred patients including key eligibility criteria. If these are met, the study nurse will contact the patient, explain the study, determine the remaining eligibility criteria and obtain consent. The nurse will use the electronic database to randomly allocate the patient to open or endovascular repair. We will ensure concealment of allocation through the use of a randomization and allocation process housed on an encrypted website monitored by a data coordinator external to the study protocol. This process has been successfully developed within the St Joseph's Nephrology, Thromboembolism and Vascular research group. Randomization using random-sized permuted block technique will ensure balanced distribution of patients and concealment of allocation. Once allocation has occurred, the study nurse will coordinate patient appointments to the appropriate surgeon. Patients who do not meet eligibility requirements will return to their original surgeon for disclosure of results and treatment. Patient Follow-up The study nurse will meet the patient, document baseline characteristics and perform blood work at the preoperative clinic visit. The study nurse will see patients daily after surgery, arrange daily blood work and document all outcome events using standardized case report forms until discharged from hospital. An outcome assessor committee independent of the study and blinded to treatment allocation will adjudicate all outcome events. The study nurse will see all patients at 3-month intervals for 6 months. The use of a 6-month outcome threshold is for purposes of assessing feasibility in this pilot study only. The larger multicentre trial will plan to evaluate outcomes up to five years, addressing the long term concerns that have been raised in RCTs. Evaluation of Pilot Objectives We will consider the pilot study a success if we can: 1. Recruit 30 patients in 40 weeks 2. Obtain a complete follow-up on 95% of the trial patients 3. Demonstrate the feasibility of using a web-based system to randomize and follow patients in this trial, and for outcome adjudication, and 4. Document the resources (e.g., personnel time) required to conduct this trial. Ethical Considerations All patients in this study will provide informed consent prior to participation, and the protocol will be reviewed by the Ethics Review Board of Hamilton Health Sciences. Reference List 1. Lindholt JS, Juul S, Fasting H, Henneberg EW. Screening for abdominal aortic aneurysms: single centre randomised controlled trial. 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