title: Oxfordshire community stroke project classification poorly differentiates small cortical and subcortical infarcts.
abstract: OBJECTIVE
  The Oxfordshire Community Stroke Project (OCSP) is a common clinical stroke classification tool. We evaluated the accuracy of OCSP classification with a prospective magnetic resonance imaging (MRI) study.
  
  
  METHODS
  Stroke/transient ischemic attack patients presenting within 48 hours of onset were included in the study (n=130). Following computed tomography scan, OCSP classification, total anterior circulation infarcts (TACI), partial anterior circulation infarcts (PACI), lacunar circulation infarcts (LACI), and posterior circulation infarcts (POCI) were performed by 3 independent examiners. All patients underwent diffusion-weighted MRI with planimetric volume measurement and classification into OCSP categories, organized by lesion location.
  
  
  RESULTS
  Patients were clinically classified as TACI (12 patients), PACI (62 patients), LACI (38 patients), and POCI (18 patients). In 101 patients with diffusion-weighted MRI lesions, correct classification rates were: TACI (83.3%), PACI (83%), LACI (39%), and POCI (86%). OCSP had the following sensitivity (SE), specificity (SP), and positive predictive value (PPV): TACI (SE, 100%; SP, 98%; PPV, 83%), PACI (SE, 73%; SP, 78%; PPV, 83%), LACI (SE, 47%; SP, 83%; PPV, 39%), and POCI (SE, 92%; SP, 98%; PPV, 86%). Sixty-one percent of patients in the LACI group had radiographic appearances consistent with PACI, and 15% of those classified as PACI had lacunar infarcts. No differences in stroke severity existed between patients classified correctly (median National Institutes of Health Stroke Scale [NIHSS]=4; interquartile range [IQR]=7) or incorrectly (median NIHSS=3; IQR=3). Patients classified correctly had larger infarct volume (median=6.75 mL; IQR=33.2) than did those who were incorrectly classified (1.86 mL; IQR=5; P=0.008).
  
  
  CONCLUSIONS
  OCSP classification does not permit accurate discrimination between lacunar and small-volume cortical infarcts. Differential patterns of investigation for stroke etiology should not be based solely on clinical criteria.
authors.affiliation: Division of Neurology, University of Alberta, Alberta, Canada.
authors.forename: Negar
authors.initials: N
authors.lastname: Asdaghi
authors.forename: Thomas
authors.initials: T
authors.lastname: Jeerakathil
authors.forename: Bilal
authors.initials: B
authors.lastname: Hameed
authors.forename: Monica
authors.initials: M
authors.lastname: Saini
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: McCombe
authors.forename: Ashfaq
authors.initials: A
authors.lastname: Shuaib
authors.forename: Derek
authors.initials: D
authors.lastname: Emery
authors.forename: Kenneth
authors.initials: K
authors.lastname: Butcher
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging; D002545:Brain Ischemia / Q000145:classification* / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012680:Sensitivity and Specificity; D020521:Stroke / Q000145:classification* / Q000000981:diagnostic imaging