title: Using Radiological Data to Estimate Ischemic Stroke Severity.
abstract: BACKGROUND
  Risk-adjusted poststroke mortality has been proposed for use as a measure of stroke care quality. Although valid measures of stroke severity (e.g., the National Institutes of Health Stroke Scale [NIHSS]) are not typically available in administrative datasets, radiology reports are often available within electronic health records. We sought to examine whether admission head computed tomography data could be used to estimate stroke severity.
  
  
  METHODS
  Using chart review data from a cohort of acute ischemic stroke patients (1998-2003), we developed a radiographic measure ([BIS]) of stroke severity in a two-third development set and assessed in a one-third validation set. The retrospective NIHSS was dichotomized as mild/moderate (<10) and severe (≥10). We compared the association of this radiographic score with NIHSS and in-hospital mortality at the patient level.
  
  
  RESULTS
  Among 1348 stroke patients, 86.5% had abnormal findings on initial head computed tomography. The c-statistic for the BIS for modeling severe stroke (development, .581; validation, .579) and in-hospital mortality (development, .623; validation, .678) were generated.
  
  
  CONCLUSIONS
  Although the c-statistics were only moderate, the BIS provided significant risk stratification information with a 2-variable score. Until administrative data routinely includes a valid measure of stroke severity, radiographic data may provide information for use in risk adjustment.
authors.affiliation: Neurology Service, VA Connecticut Healthcare System, West Haven, Connecticut; Department of Neurology and Center for NeuroEpidemiological and Clinical Neurological Research, Yale University School of Medicine, New Haven, Connecticut; Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut. Electronic address: Jason.sico@yale.edu.
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Sico
authors.affiliation: Department of Neurology, University of Maryland, Baltimore, Maryland; Department of Epidemiology and Public Health, University of Maryland, Baltimore, Maryland.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Phipps
authors.affiliation: Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut; Medicine Service, VA Connecticut Healthcare System, West Haven, Connecticut; Clinical Epidemiology Research Center (CERC), VA Connecticut Healthcare System, West Haven, Connecticut.
authors.forename: John
authors.initials: J
authors.lastname: Concato
authors.affiliation: Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Brandt
authors.affiliation: Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut; Clinical Epidemiology Research Center (CERC), VA Connecticut Healthcare System, West Haven, Connecticut.
authors.forename: Carolyn K
authors.initials: CK
authors.lastname: Wells
authors.affiliation: Department of Neurology, Warren Alpert School of Medicine and Departments of Neurosciences, Community Health, and Engineering at Brown University, Providence, Rhode Island; Providence Veterans Administration Medical Center, Providence, Rhode Island.
authors.forename: Albert C
authors.initials: AC
authors.lastname: Lo
authors.affiliation: Neurology Service, Malcolm Randall VA Medical Center, Gainesville, Florida; Department of Neurology, University of Florida School of Medicine, Gainesville, Florida.
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Nadeau
authors.affiliation: VA Health Services Research and Development (HSR&D) Center for Health Information and Communication (CHIC) and the HSR&D Stroke Quality Enhancement Research Initiative (QUERI), Richard L. Roudebush VA Medical Center, Indianapolis, Indiana; Department of Neurology, Indiana University School of Medicine, Regenstrief Institute, Indianapolis, Indiana.
authors.forename: Linda S
authors.initials: LS
authors.lastname: Williams
authors.affiliation: Department of Neurology, University of Vermont School of Medicine, Burlington, Vermont.
authors.forename: Mark
authors.initials: M
authors.lastname: Gorman
authors.affiliation: Medical Service, Boise VA Medical Center, Boise, Virginia.
authors.forename: John L
authors.initials: JL
authors.lastname: Boice
authors.affiliation: VA Health Services Research and Development (HSR&D) Center for Health Information and Communication (CHIC) and the HSR&D Stroke Quality Enhancement Research Initiative (QUERI), Richard L. Roudebush VA Medical Center, Indianapolis, Indiana; Department of Internal Medicine, Indiana University School of Medicine, Regenstrief Institute, Indianapolis, Indiana.
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Bravata
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging*; D002545:Brain Ischemia / Q000150:complications / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D059906:Neuroimaging / Q000379:methods*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D020521:Stroke / Q000000981:diagnostic imaging* / Q000209:etiology
keywords: CT scan; Ischemic stroke; NIHSS; imaging