Overview

A planned multicentre randomised PROBE trial comparing surgical clipping with contemporary endovascular treatment for unruptured anterior circulation intracranial aneurysms.

The trial in one sentence

IUAT is a planned multicentre randomised trial comparing surgical clipping with contemporary endovascular treatment for unruptured anterior circulation intracranial aneurysms.

The trial is designed for the clinical question that neurovascular teams face in routine practice: when both open microsurgical clipping and endovascular treatment are technically feasible and clinically reasonable, which strategy gives better patient-centred outcomes?

Trial at a glance

Parameter	IUAT
Full name	International Unruptured Aneurysm Trial
Clinical question	Surgical clipping versus contemporary endovascular treatment for unruptured anterior circulation aneurysms
Design	Multicentre, prospective, randomised, open-label, blinded-endpoint PROBE trial
Population	Adults with unruptured anterior circulation intracranial aneurysms where both modalities are reasonable
Randomisation	1:1 allocation to clipping or endovascular treatment
Primary endpoint	Patient safety, COSMOS, recovery trajectory
Planned scale	570–1,000 participants, final sample size to be confirmed with CTU biostatistics
Follow-up	12-month primary outcome, with extended 2-year and 5-year follow-up for clinical and durability outcomes
Sponsor	Barking, Havering and Redbridge University Hospitals NHS Trust
Current status	Planning, protocol refinement, CTU partnership and funding development

Why physicians should be interested

Unruptured intracranial aneurysms are increasingly detected because of high-resolution neuroimaging. Clinicians then face a high-stakes elective treatment decision in neurologically intact patients: treat or observe, and if treating, whether to use surgical clipping or an endovascular strategy.

Current practice is still shaped by observational data, local culture and extrapolation from ruptured aneurysm trials. IUAT is designed to provide the randomised evidence needed for the treatment-versus-treatment decision.

What makes IUAT different

IUAT compares modern clipping techniques with the full contemporary endovascular treatment strategy, including conventional coiling, balloon-assisted coiling, stent-assisted coiling, intrasaccular devices and flow diversion where appropriate.

It is not built around mRS alone. Elective aneurysm patients may remain functionally independent by mRS while still experiencing important differences in cognition, fatigue, return to work and participation. IUAT therefore prioritises safety first, then patient-centred function, then recovery.

IUAT is designed to answer the unruptured aneurysm question in the same spirit that ISAT answered the ruptured aneurysm question: a pragmatic, clinically important trial aimed at changing practice.

Current purpose of this website

This website is aimed primarily at physicians and centres with an interest in taking part. It is not a patient recruitment website. IUAT is not yet open to patient enrolment.