Assessing the clinical and cost-effectiveness of endovascular vs open revascularisation in severe occlusive aorto-iliac disease (EVOCC trial): Study protocol for a randomised controlled trial

INTRODUCTION: Severe aorto-iliac steno-occlusive atherosclerotic disease is a major cause of morbidity and amputation in patients with peripheral arterial disease. While both open surgical and endovascular revascularisation are standard treatments in this patient group, there is no high-quality randomised evidence to determine which approach offers superior clinical and cost-effectiveness, leading to uncertainty and poor outcomes after intervention.

METHODS AND ANALYSIS: The EVOCC trial is a national, multicentre, parallel-group, superiority randomised controlled trial comparing open surgery to endovascular revascularisation in patients with symptomatic severe aorto-iliac occlusive disease. A total of 628 participants across 30 NHS sites in the UK will be randomised 1:1 to receive either open surgery or endovascular (minimally invasive) intervention. The primary outcome is amputation-free survival, defined as time to first event (major lower limb amputation or death). Secondary outcomes include mortality, cardiovascular events, hospital readmissions, re-interventions and quality-of-life measures. An internal pilot phase (10 sites, 6-month duration) will assess recruitment feasibility. A QuinteT Recruitment Intervention is integrated into the trial to optimise recruitment.

ETHICS AND DISSEMINATION: The trial has received ethical approval from a UK Research Ethics Committee (REC reference: 23/SW/0065; trial registration reference: ISRCTN14591444). Informed consent will be obtained from all participants.The EVOCC trial is the first RCT assessing the clinical and cost-effectiveness of open vs endovascular revascularisation for severe aorto-iliac disease worldwide. The results will provide robust evidence to inform clinical practice and healthcare policies globally. Results will be disseminated via patient groups, online lay summaries, a trial website, social media, presentations in conferences, a formal scientific publication in a medical journal and direct communications with policymakers across borders.

TRIAL REGISTRATION NUMBER: ISRCTN14591444.