Background Rapid treatment of stroke can improve the chances of recovery. It is important that patients are assessed quickly to decide if it is appropriate to deliver thrombolysis treatment. This study is evaluating whether an enhanced assessment by paramedics could speed up treatment and improve stroke recovery.

Study design Multicentre cluster randomised trial with cost-effectiveness analysis and parallel process evaluation.

Setting NHS ambulance services, emergency departments and stroke units within three geographical regions of England and Wales.

Study intervention A Paramedic Acute Stroke Treatment Assessment (PASTA) pathway initiated by paramedics and continued initially in hospital to facilitate the speed of brain imaging and delivery of thrombolysis when clinically appropriate.

Study control Usual care according to national and local guidelines for the pre-hospital and hospital assessment of suspected stroke.

Randomisation Ambulance stations or paramedic teams within each region randomised to delivering the PASTA pathway or to continue with usual stroke care.

Participants Intervention paramedics will deliver the PASTA pathway to adults within 4 hours of suspected stroke onset. Participants enrolled in the study will be adults with confirmed stroke who were assessed by a study paramedic within 4 hours of onset.

Primary outcome Dependency at 90 days after stroke (modified Rankin Scale)

Process evaluation Semi-structured interviews with a subsample of participants and staff to gain insight into perceptions and experience of the PASTA pathway.

Sample size Allowing for 3% attrition, 3640 participants are needed to provide 80% power to detect a 3% absolute difference in mRS 3–6 (poor outcome) to mRS 0–2 (good outcome).

Current study status Opened to recruitment in December 2015.