title: Injury severity as primary predictor of outcome in acute spinal cord injury: retrospective results from a large multicenter clinical trial.
abstract: BACKGROUND
  The prognostic value of injury severity and of anatomical region in acute spinal cord injury is strong, making it hard to evaluate other indicators or assess improvement without considering them.
  
  
  OBJECTIVE
  This study documents issues and suggests a practical way to stratify.
  
  
  METHODS
  Retrospective analysis of data prospectively collected for the multicenter trial of GM-1.
  
  
  METHODS
  A total of 760 patients were recruited at 28 centers in North America. Injuries were rostral to T10 and left at least one leg with an American Spinal Injury Association (ASIA) motor score less than 15 of 25. Patients were assessed at baseline using the ASIA Impairment Scale (AIS): Grade A, Grade B, and Grades C and D (combined). They were divided by injury region: cervical or thoracic.
  
  
  METHODS
  The endpoint was marked recovery (MR), defined as improvement of at least two grades from AIS at baseline to Modified Benzel Scale at Week 26. Other endpoints were changes in ASIA Motor, in light touch, and in pin prick scores.
  
  
  METHODS
  Data were verified onsite by a central team of monitors, the database was checked and standard statistical techniques were applied.
  
  
  RESULTS
  Recruitment was uneven. In 760 patients, 579 injuries were cervical, and 482 were complete. There were few incomplete thoracic injuries. The cervical group had more MR than the thoracic group (37.2% vs 15.9%, p< .0001). AIS Groups C and D had (p< .0001) more MR (84.0%) than Group B (46.6%), which recovered more than Group A (12.8%). The cervical group had an advantage in MR because it had more patients with AIS B, and still more AIS C and D. Within AIS Group A, the cervical subgroup had (p< .02) higher MR (15.5%) than the thoracic one (7.0%), but MR was nearly equal in the B and CD groups. This suggested a new stratification variable, "injury region/severity," to distinguish cervical (n=332, MR=15.5%) and thoracic (n=150, MR=7.0%) injuries within AIS A, but not in AIS B (n=131, MR=46.6%) or AIS CD (n=147, MR=84.1%). This variable is a significant predictor of MR (p< .0001).
  
  
  CONCLUSIONS
  AIS severity was the strongest predictor. Anatomical region was also strong but confounded with the severity effect, because the cervicals had fewer complete injuries, and because the cervical complete group did better than thoracic complete. The injury region/severity variable keeps the strong prognostic value of using both region and severity, but is simpler and more statistically economical.
authors.affiliation: WPCMath, 703 West Ferry Street, C-20, Buffalo, NY 14222, USA.
authors.forename: William P
authors.initials: WP
authors.lastname: Coleman
authors.forename: Fred H
authors.initials: FH
authors.lastname: Geisler
mesh_terms: D000208:Acute Disease; D002574:Cervical Vertebrae / Q000293:injuries; D016009:Chi-Square Distribution; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D015601:Injury Severity Score; D008297:Male; D015337:Multicenter Studies as Topic; D010264:Paraplegia / Q000175:diagnosis / Q000628:therapy; D011237:Predictive Value of Tests; D011336:Probability; D011782:Quadriplegia / Q000175:diagnosis / Q000628:therapy; D011788:Quality of Life; D012189:Retrospective Studies; D018434:Sickness Impact Profile; D013119:Spinal Cord Injuries / Q000175:diagnosis* / Q000628:therapy*; D018709:Statistics, Nonparametric; D013904:Thoracic Vertebrae / Q000293:injuries; D015599:Trauma Severity Indices; D016896:Treatment Outcome