Every year, around 1,150 ambulance patients in England will be randomly assigned to either a new prehospital redirection pathway or standard stroke care, in a trial testing whether paramedics can bypass local hospitals and take suspected large artery occlusion stroke patients directly to one of 24 regional Thrombectomy Centres. This matters because thrombectomy can prevent severe disability after a major stroke, but the current system typically adds 90 minutes to treatment time by requiring patients to first go to a local hospital before being transferred. No validated prehospital assessment or care pathway exists to identify these patients before they reach a hospital. If the trial succeeds, the research will provide an evidence-based pathway for ambulance services to selectively redirect patients, reducing onset-to-treatment time and improving outcomes. The second phase will then model how each of England’s 24 regional centres should configure its surrounding ambulance zones for optimal clinical and cost-effectiveness. The project has no immediate practical application beyond the trial itself. If the pathway proves effective, it could reshape emergency stroke infrastructure across England, reducing long-term disability and care costs for thousands of patients each year.
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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 <5 hours since suspected stroke onset exhibiting pathway-trigger symptoms agreed by stakeholders. - 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.
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