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Positive predictive value of stroke identification by ambulance clinicians in North East England: a service evaluation
  1. Graham McClelland1,2,
  2. Darren Flynn3,
  3. Helen Rodgers2,
  4. Christopher Price2
  1. 1 Research and Development, North East Ambulance Service NHS Foundation Trust, Newcastle upon Tyne, UK
  2. 2 Institute of Neuroscience (Stroke Research Group), Newcastle University Faculty of Medical Sciences, Newcastle upon Tyne, UK
  3. 3 Teesside University School of Health and Social Care, Middlesbrough, UK
  1. Correspondence to Dr Graham McClelland, Research and Development, North East Ambulance Service NHS Foundation Trust, Newcastle upon Tyne NE158NY, UK; graham.mcclelland{at}neas.nhs.uk

Abstract

Introduction/background Accurate prehospital identification of patients who had an acute stroke enables rapid conveyance to specialist units for time-dependent treatments such as thrombolysis and thrombectomy. Misidentification leads to patients who had a ‘stroke mimic’ (SM) being inappropriately triaged to specialist units. We evaluated the positive predictive value (PPV) of prehospital stroke identification by ambulance clinicians in the North East of England.

Methods This service evaluation linked routinely collected records from a UK regional ambulance service identifying adults with any clinical impression of suspected stroke to diagnostic data from four National Health Service hospital trusts between 1 June 2013 and 31 May 2016. The reference standard for a confirmed stroke diagnosis was inclusion in Sentinel Stroke National Audit Programme data or a hospital diagnosis of stroke or transient ischaemic attack in Hospital Episode Statistics. PPV was calculated as a measure of diagnostic accuracy.

Results Ambulance clinicians in North East England identified 5645 patients who had a suspected stroke (mean age 73.2 years, 48% male). At least one Face Arm Speech Test (FAST) symptom was documented for 93% of patients who had a suspected stroke but a positive FAST was only documented for 51%. Stroke, or transient ischaemic attack, was the final diagnosis for 3483 (62%) patients. SM (false positives) accounted for 38% of suspected strokes identified by ambulance clinicians and included a wide range of non-stroke diagnoses including infections, seizures and migraine.

Discussion In this large multisite data set, identification of patients who had a stroke by ambulance clinicians had a PPV rate of 62% (95% CI 61 to 63). Most patients who had a suspected stroke had at least one FAST symptom, but failure to document a complete test was common. Training for stroke identification and SM rates need to be considered when planning service provision and capacity.

  • stroke
  • prehospital care
  • diagnosis
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Footnotes

  • Twitter @mcclg

  • Contributors GM designed and conducted this study, analysed the data and wrote the manuscript. DF, HR and CP advised on all stages of the study and contributed to the final manuscript.

  • Funding The Stroke Association funded this work through their postgraduate fellowship scheme.

  • Competing interests GM reports grants from the Stroke Association, during the conduct of the study. DF reports grants from the National Institute for Health Research (Programme Grants for Applied Research, title: Promoting Effective and Rapid Stroke care (PEARS), project number: RP-PG-1211-20012), during the conduct of the study. HR reports grants from the NIHR, during the conduct of the study; personal fees from Bayer, outside the submitted work; and member of NIHR HTA CET panel 2010–2014. CP reports grants from the Stroke Association, during the conduct of the study.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Patient consent for publication Not required.

  • Ethics approval No ethical approval was required as this service evaluation used routinely recorded information. Caldicott guardian approvals were granted by each NHS organisation for data sharing and use. This service evaluation project was registered with Newcastle Hospitals (project 7506, 29 March 2017).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available upon reasonable request.

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