Title: OPTimising IMplementation of Ischaemic Stroke Thrombectomy (OptImIST)
Funder: Department of Health and Social Care

Abstract: Background Thrombectomy can avoid severe disability when large artery occlusion causes acute ischaemic stroke but treatment is only available at 24 regional Centres. The majority of suitable patients must undergo urgent secondary transfer, which typically extends onset-to-treatment time by 90-minutes. Outcomes would be improved if patients were identified before local admission and taken directly to regional Centres, but no appropriate assessment, test or care pathway exists. If a prehospital selective redirection pathway was developed and shown to be effective, implementation in zones around each Centre could reduce disability and care costs. Aim To improve outcomes for the emergency stroke population by optimising delivery of thrombectomy treatment for acute ischaemic stroke caused by large artery occlusion. Research Questions There are two Research Questions: 1. Should a structured remote specialist assessment triggered by routinely collected prehospital information be used to selectively redirect patients likely to have large artery occlusion towards regional Thrombectomy Centres? 2. How should regional pathways be configured around each Thrombectomy Centre in England to achieve optimal clinical effectiveness and cost-effectiveness? Methods Work Packages for Research Question 1 are: 1) Development of a new specialist prehospital redirection thrombectomy pathway through literature review and multidisciplinary stakeholder engagement. 2) A pragmatic, multicentre, cluster randomised trial to evaluate pathway effectiveness consisting of: - Cluster randomisation: ambulance stations (work bases for ambulance practitioners) will be randomised 1:1 to deliver the new pathway or continue standard stroke care. - Population: medically stable ambulance patients - Intervention: specialist prehospital redirection pathway comprising i) pathway initiation using routine information by ambulance practitioners; ii) Thrombectomy Centre enhanced prenotification by phone; iii) remote specialist assessment to select patients for redirection. - Co-primary outcome: thrombectomy treatment rate and onset-to-treatment time examined using a two-part regression model. - Secondary outcomes: population characteristics; key time intervals; stroke thrombolysis - Sample size: 1150 patients are required to detect a 6% change in treatment rate within the study population; 564 thrombectomy treatments are required to detect a 30-minute onset-to-treatment time saving (p=0.05; power 90%; interclass correlation coefficient 0.01). 3) A process evaluation of professional and patient experience during the intervention pathway 4) A within-trial economic evaluation and cost utility analysis using trial data. Work Packages for Research Question 2 are: 1) multi-professional focus groups and literature searches to identify important system-wide factors and clinical evidence relevant to delivery of thrombectomy services in England. 2) geographical pathway modelling using Research Question 1 trial results to define optimal region-specific thrombectomy pathway configurations, with sensitivity analyses to examine the impact of key system-wide factors and new clinical evidence. Timelines for delivery Research Question 1 duration is 60 months (WP1: 1-18m; WP2: 5-60m with an internal pilot phase 14-17m; WP3: 14-48m; WP4: 49-60m). Research Question 2 duration is 36 months (WP1: 25-42m; WP2: 25-60m). Anticipated Impact and Dissemination In addition to publication in open access journals and National Clinical Guidelines, we will disseminate reports through NHS Integrated Stroke Delivery Networks, professional societies and stroke survivor networks.

Lay abstract: Aims Our Programme aims to evaluate a new way to access a life-changing emergency procedure for stroke patients which is only available in regional Centres. There are two Research Questions: 1) Should specialists at regional Centres select ambulance patients to divert to their Centre instead of the nearest local Stroke Unit? 2) How can each region in England achieve the most cost-effective emergency stroke treatment? Background Stroke is the commonest cause of adult disability. Approximately 1 in 10 patients are suitable for an emergency procedure to remove blood clots blocking large arteries in the brain (known as thrombectomy ) which greatly improves their chances of recovery. In England, this procedure is available at 24 regional Centres with specialist facilities, but most stroke patients are first admitted to 108 local Stroke Units. Patients suitable for the procedure need emergency transfer to a regional Centre, which typically delays treatment by 90 minutes and reduces its benefit. Faster treatment might occur if patients could attend Centres directly rather than local Units, but no accurate assessment or portable test exists to guide ambulance staff. However, staff collect information during routine care which could start a process to find and quickly treat suitable patients. Design For Research Question 1 we will firstly summarise existing evidence about remote assessment of suspected stroke patients and collect opinions from ambulance and hospital teams to develop a new specialist prehospital redirection pathway . The pathway will involve ambulance staff triggering a remote review of suspected stroke patients by a hospital specialist, who then selects which patients should go directly to the nearest Centre. To find out whether the pathway is beneficial, a clinical trial will then be conducted. Patients with a suspected stroke will receive either the new pathway or standard care. Data describing treatment delivery will be compared between these two groups. Experiences and views about the pathway will be collected during patient and clinician interviews. For Research Question 2, advanced computer models will calculate how to provide the most cost-effective treatment. The models will combine geographical, healthcare and trial data with stakeholder views and other published evidence describing selection of stroke patients for emergency treatment. Patient and public involvement The project team includes a stroke survivor to provide service user perspectives into the routine management of the Programme. Public volunteers from each clinical service involved in the trial will meet regularly as a Programme PPI Partnership Group to review progress and provide advice to the researchers. Dissemination Research reports will be published in journals and findings included in National Clinical Guidelines for hospitals and ambulance services. We will also use NHS Integrated Stroke Delivery Networks and professional societies to distribute reports. Stroke survivor networks will receive easily accessible versions.

Research activity codes: 8.1 ORGANISATION AND DELIVERY OF SERVICES
Health categories: STROKE