Retrospective safety testing of the CT Clock
Research type
Research Study
Full title
Retrospective safety testing of the CT Clock method for identifying treatment-eligible patients with ischaemic stroke of unknown onset time
IRAS ID
367252
Contact name
Grant Mair
Contact email
Sponsor organisation
University of Edinburgh
Duration of Study in the UK
0 years, 7 months, 31 days
Research summary
Ischaemic stroke occurs when a blood clot blocks blood supply to the brain causing sudden symptoms such as weakness and speech problems. Over 80,000 people in the UK are affected every year. Stroke has a high death rate, and many survivors are left disabled.
Treatment with a ‘clot-busting’ drug (thrombolysis) can reduce disability and death from ischaemic stroke by restoring blood supply to the brain. Thrombolysis is usually given within 4.5 hours of stroke occurring. Unfortunately, most patients with ischaemic stroke arrive in hospital later than this, or it is unclear when their stroke started. For these patients, thrombolysis may still be possible if the hospital provides an additional advanced brain scan. However, many hospitals cannot offer this advanced scan.
We have developed a new method for identifying which patients can be given thrombolysis even if they arrive at hospital late, or with uncertainty about when their stroke started. Our method is called the CT Clock. It does not require any additional or advanced imaging. Instead, we ask doctors who provide stroke care to measure the injured brain on the standard CT scan that all patients with stroke get when they arrive at hospital. These measurements provide an indication of how severely the brain is injured and are used to decide if a patient is still suitable for thrombolysis.
Here we propose to test the safety of our CT Clock method in an analysis of existing NHS data from patients who have previously been treated with thrombolysis. We aim to show that when doctors use our method to identify patients for thrombolysis, it is safe for these patients.
By using existing NHS data, there is no risk of harm to individuals. However, we will be unable to obtain consent from the patients whose data we would like to use. Instead, we will seek approval from the local NHS Caldicott Guardian and an independent Research Ethics Committee. We will remove all identifiable information from the data before we use it.
REC name
East of Scotland Research Ethics Service REC 2
REC reference
26/ES/0009
Date of REC Opinion
24 Feb 2026
REC opinion
Further Information Favourable Opinion