The unruptured aneurysm question needs a definitive trial.

IUAT is a planned multicentre, randomised, open-label, blinded-endpoint trial comparing surgical clipping with contemporary endovascular treatment for unruptured anterior circulation intracranial aneurysms.

Current status: planning, protocol refinement, CTU partnership and funding development. Not yet open for patient recruitment.

IUAT International Unruptured Aneurysm Trial logo
2–5%of adults carry an unruptured intracranial aneurysm
Zerodefinitive RCTs comparing clipping with the full contemporary EVT portfolio
570–1,000planned participants, final calculation with CTU biostatistics
15+UK neurovascular centres, with international expansion planned

Why IUAT?

Unruptured aneurysms are increasingly detected, but clinicians still lack robust randomised evidence for the central treatment decision: clipping or endovascular treatment.

Read the rationale
TEAM

Treatment versus observation failed to recruit

IUAT uses the deliverable treatment-versus-treatment question.

CURES

Clip versus EVT is recruitable, but the evidence remains incomplete

The pilot did not test the full modern endovascular portfolio.

2025

PRAEMIUM provides contemporary surgical risk benchmarks

These data help power a rigorous new study.

IUAT

Contemporary EVT, patient-centred outcomes and blinded adjudication

A strategy trial designed around clinical equipoise and outcomes that matter to elective patients.

For interested physicians and centres

IUAT is seeking neurovascular centres where both clipping and contemporary endovascular treatment are technically feasible and clinically reasonable for eligible patients.

Design

PROBE randomised trial

Multicentre, prospective, randomised, open-label, blinded-endpoint design with 1:1 allocation.

Comparator

Full contemporary EVT portfolio

Conventional coiling, balloon-assisted coiling, stent-assisted coiling, intrasaccular devices and flow diversion where appropriate.

Endpoint

Hierarchical win ratio

Safety first, then COSMOS patient-centred function, then recovery trajectory.