Unruptured Intracranial Aneurysm Aspirin Trial (UIAAT).

The Unruptured Intracranial Aneurysm Aspirin Trial (UIAAT) is a single centre, randomised, single blind, open label trial of 300mg aspirin daily versus no treatment for 3 months. 58 patients with an intracranial aneurysm diagnosed on imaging will be recruited - potential participants will be approached by their consultant neurosurgeon or a member of their direct clinical care team.

Patient interviews will take place at Wessex Neurological Centre to coincide wherever possible with standard appointments. Participants will be screened for eligibility and consented during this interview. Following consent, baseline data will be taken to include participants' baseline characteristics, other medications, and comorbidities.

The patients will then undergo a baseline MRI including VWI imaging, and then be randomised to either the 'aspirin 300mg daily' or 'no treatment' arms.

All participants will then be called by a member of the trial team between days 7 and 21 after being commenced in either arm of the trial, to review any issues with taking the medication if they are on that arm, whether they are using their drug diary, and to check for any adverse reactions or events.

Following three months of their allocated treatment, patients will undergo a second, identical MRI scan, to assess whether there is any reduction in the inflammation in the vessel walls of the aneurysms. Patients will be reviewed at this time with their drug dairy, for drug reconciliation and recording of any adverse events. This will be the end of their participation in the trial.

The study topic and design was discussed at a meeting to set research priorities advertised via the Wessex Subarachnoid Haemorrhage group that was convened by a consultant neurosurgeon and a subarachnoid haemorrhage specialist nurse with patients with unruptured and ruptured aneurysms and their carers. At this meeting the investigators clearly identified that it would be beneficial for more research into medical treatments for unruptured aneurysms and felt that with the evidence that the group would be happy to undergo the main two items required for participation in the study - treatment with aspirin and increased scanning frequency and were very supportive of the study design. Indeed the group saw the additional scanning as a strong attraction to participating in the study.