title: PreHospital Ambulance Stroke Test - pilot study of a novel stroke test.
abstract: BACKGROUND
  There is a need for a prehospital stroke test that in addition to high sensitivity for stroke, also is able to communicate stroke severity similar to the National Institute of Health Stroke Scale (NIHSS).
  
  
  METHODS
  The PreHospital Ambulance Stroke Test (PreHAST), an eight item test based on NIHSS, which scores stroke severity from 0-19 points, was designed and adapted for the ambulance services. In the pilot study the ambulance nurses used PreHAST to assess patients with suspected stroke in the prehospital setting. Regardless of the results after PreHAST testing the patients were triaged with a provisional stroke diagnosis. The PreHAST scores were compared with the final diagnosis and the ability to differentiate stroke and transient ischemic attacks (TIA) with ongoing symptoms at evaluation from non-stroke patients was analysed.
  
  
  RESULTS
  69 patients were included in the study, 26 had stroke/TIA and 43 other diagnoses. All stroke/TIA patients were identified by PreHAST (sensitivity 100% (95% CI; 87-100%)). The specificity increased with higher PreHAST scores and the discriminative capacity for PreHAST for different cut off values showed an area under the curve of 0.77 (95%CI; 0.66-0.88) in the receiver operating characteristic (ROC) analysis.
  
  
  CONCLUSIONS
  PreHAST is designed for high sensitivity, screening for a broad range of stroke symptoms including most key components of NIHSS. The promising sensitivity between 87 and 100% in our study has to be confirmed in a larger study also including multiple centres. Higher PreHAST scores implied more typical patterns of stroke and accordingly the proportion of stroke mimics decrease with higher scores. However, also stroke mimics with epilepsy/seizure and patients with deficit after prior stroke could show higher PreHAST scores. Other prehospital stroke tests that evaluate stroke severity have been designed with the main purpose to screen for large vessel occlusion. The advantage of PreHAST is the dual purpose not only to evaluate stroke severity but also to screen for stroke in general.
  
  
  CONCLUSIONS
  PreHAST is a new screening test of stroke adapted for ambulance services that in addition to high sensitivity for stroke, provides a grading system with increasing specificity with higher scores.
authors.affiliation: Department of Rehabilitation Medicine and Neurology, Lund University, Skane University Hospital, Lund, SE-221 85, Sweden. gunnar.andsberg@med.lu.se.
authors.forename: Gunnar
authors.identifier: http://orcid.org/0000-0002-7471-0369
authors.initials: G
authors.lastname: Andsberg
authors.affiliation: Department of Medicine, Hässleholm, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Esbjörnsson
authors.affiliation: Region Skåne Prehospital Unit, Lund, Sweden.
authors.forename: Arne
authors.initials: A
authors.lastname: Olofsson
authors.affiliation: Department of Rehabilitation Medicine and Neurology, Lund University, Skane University Hospital, Lund, SE-221 85, Sweden.
authors.forename: Arne
authors.initials: A
authors.lastname: Lindgren
authors.affiliation: Department of Rehabilitation Medicine and Neurology, Lund University, Skane University Hospital, Lund, SE-221 85, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Norrving
authors.affiliation: Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Karolinska Institutet Stroke Research Network at Södersjukhuset, Stockholm, Sweden.
authors.forename: Mia
authors.initials: M
authors.lastname: von Euler
mesh_terms: D000552:Ambulances; D003943:Diagnostic Techniques, Neurological; D004632:Emergency Medical Services / Q000379:methods*; D006801:Humans; D008403:Mass Screening; D010865:Pilot Projects; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D020521:Stroke / Q000175:diagnosis*
keywords: Cerebrovascular diseases; Prehospital; Stroke Scale; Strokes; TIA; Treatment