title: Defining age-related differences in outcome after traumatic spinal cord injury: analysis of a combined, multicenter dataset.
abstract: BACKGROUND
  The existing evidence suggests that, although older spinal cord injury (SCI) patients experience a similar degree of neurologic recovery to younger patients, older patients experience diminished functional outcomes at follow-up. However, all studies have assumed that the impact of age on functional outcome is the same across the spectrum of injury severity.
  
  
  OBJECTIVE
  To test this assumption, we evaluated age as a potential effect moderator governing the relationship between acute neurologic status and long-term functional outcome.
  
  
  METHODS
  Combined analysis of two prospective SCI datasets enrolling patients from North American trauma centers over the last decade.
  
  
  METHODS
  Adult patients (≥16 years old) with traumatic SCI and a standardized American Spinal Injury Association (ASIA) neurologic examination performed within 3 days of injury.
  
  
  METHODS
  Functional independence measure (FIM) motor score at the 1-year follow-up was the primary outcome of interest.
  
  
  METHODS
  To define older and younger age groups, age was dichotomized at a threshold of 65 years old. A sensitivity analysis was also performed by dichotomizing age at 60 years. Multivariable linear regression was used to investigate the moderating effects of age on the relationship between acute ASIA Impairment Scale (AIS) grade and follow-up FIM motor score. An interaction plot was generated to understand how the effect of age on functional outcome changed depending on the acute AIS grade. A second linear regression model investigating the moderating effects of age was produced that adjusted for additional relevant predictor variables.
  
  
  RESULTS
  Of 729 patients, 376 met the eligibility criteria. The mean age was 43.2 (±16.9), with a total of 41 patients (10.9%) older than 65 years. In the univariable analysis there was no age-related difference in motor recovery or AIS grade conversion at follow-up; however, there was a significantly lower mean FIM motor score observed among the older group at 1 year (p=.03). In the multivariable analysis, age was found to have a significant moderating effect on the relationship between acute AIS grade and future functional status (p<.05). The interaction plot revealed that, although older patients had decreased follow-up FIM motor scores overall, this effect was greatest for AIS B and AIS C patients and lesser for AIS A and AIS D patients. After adjustment for additional covariates in the second linear model, these results remained unchanged.
  
  
  CONCLUSIONS
  Overall, advanced age is associated with worse functional outcome after SCI; however, this effect varies across the spectrum of injury severity. These results will help to facilitate enhanced clinical communication as well as potentially aid in the development of customized treatment and rehabilitation protocols.
authors.affiliation: Department of Surgery, Division of Neurosurgery and Spinal Program, University of Toronto, Toronto Western Hospital, 399 Bathurst St, Toronto M5T 2S8, ON, Canada.
authors.forename: Jefferson R
authors.initials: JR
authors.lastname: Wilson
authors.affiliation: Health Care and Outcomes Research, Toronto Western Research Institute, University Health Network, University of Toronto, 399 Bathurst St, Toronto M5T 2S8, ON, Canada; Department of Health Policy, Management and Evaluation, University of Toronto, 155 College St, Suite 425, Toronto M5T 3M6, ON, Canada.
authors.forename: Aileen M
authors.initials: AM
authors.lastname: Davis
authors.affiliation: Department of Surgery, Division of Neurosurgery and Spinal Program, University of Toronto, Toronto Western Hospital, 399 Bathurst St, Toronto M5T 2S8, ON, Canada; Department of Health Policy, Management and Evaluation, University of Toronto, 155 College St, Suite 425, Toronto M5T 3M6, ON, Canada.
authors.forename: Abhaya V
authors.initials: AV
authors.lastname: Kulkarni
authors.affiliation: Department of Health Policy, Management and Evaluation, University of Toronto, 155 College St, Suite 425, Toronto M5T 3M6, ON, Canada; Department of Research Design and Biostatistics, Sunnybrook Research Institute, University of Toronto, 2075 Bayview Ave, Toronto M4N 3M5, ON, Canada.
authors.forename: Alex
authors.initials: A
authors.lastname: Kiss
authors.affiliation: School of Public Health, University of Texas, 1200 Pressler St, Houston, TX 77030, USA.
authors.forename: Ralph F
authors.initials: RF
authors.lastname: Frankowski
authors.affiliation: Department of Neurosurgery, Houston Methodist Hospital, 6565 Fannin St, Houston, TX 77030, USA.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Grossman
authors.affiliation: Department of Surgery, Division of Neurosurgery and Spinal Program, University of Toronto, Toronto Western Hospital, 399 Bathurst St, Toronto M5T 2S8, ON, Canada. Electronic address: madeleineoh@gmail.com.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fehlings
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D020127:Recovery of Function / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D014193:Trauma Centers; D015599:Trauma Severity Indices
keywords: Age; Functional outcome; North American Clinical Trials Network; Spinal cord injury; Surgical timing in spinal cord injury study