Eligibility and site selection

Summary of planned patient eligibility criteria, operator standards and site selection considerations for IUAT.

Planned patient inclusion criteria

Final eligibility criteria will be confirmed through protocol development and regulatory review. The current proposal includes:

• age 18–70 years
• unruptured anterior circulation intracranial aneurysm confirmed on CTA, MRA or DSA
• aneurysm size 4–15 mm, with possible extension to 20 mm by amendment
• pre-treatment mRS 0–1
• capacity for informed consent
• willingness to comply with follow-up
• independent evaluation by both a vascular neurosurgeon and an interventional neuroradiologist confirming equipoise

The key equipoise statement is:

Both open surgical and endovascular treatment are technically feasible and clinically reasonable for this patient.

Planned exclusions

Current exclusions include:

• previous rupture of the target aneurysm
• posterior circulation aneurysm
• fusiform, dissecting or otherwise unsuitable morphology
• contraindication to general anaesthesia
• contraindication to required antiplatelet therapy
• prior treatment of the target aneurysm
• pregnancy
• major cognitive impairment or psychiatric illness precluding assessment
• limited life expectancy

Operator standards

The protocol includes minimum operator experience standards for both treatment arms. These are intended to ensure that the trial compares high-quality clipping with high-quality contemporary EVT.

Final thresholds will be refined with the trial steering group, CTU and participating centres.

Site selection principles

IUAT should prioritise sites that combine clinical volume with genuine equipoise. High volume alone is not enough if local practice culture makes randomisation unrealistic.

The most valuable sites will be those where neurosurgery and neurointervention can jointly identify patients for whom both strategies are reasonable.