Title: Is respiratory failure driving mortality in older patients with cervical spinal cord Injuries? PRISMA meta-analysis of a poorly understood phenomenon needing more investigation.

Introduction: Cervical spinal cord injury is associated with mortality in older adults. Prior work has characterized functional and neurological outcomes as a consequence of early vs. late intervention and the role of higher level injury in poor outcomes; however, the timeline and etiologies of mortality itself are less well understood. This study seeks to explore what causes the higher mortality of cervical spine injuries in older adults in both surgically and nonsurgically treated patients.

Methods: PUBMed, SCOPUS, Web of Science, and Cochrane were reviewed by two independent research team members using the keywords: cervical spinal cord injury, elderly OR geriatric OR age above 65, and mortality OR outcomes. Inclusion criteria consisted of surgical spinal cord injury, retrospective or prospective observational or interventional studies, and analysis including outcomes of adults above 65. Individual case reports were excluded. The studies were analyzed for bias using the ROBINS-E tool, and summary data were presented in aggregate as median with inter-quartile range (IQR).

Results: 2305 articles across the 4 databases met criteria for screening. Of these, 11 met the criteria for study inclusion, all of which were Level 4 evidence for a total of 4790 patients. Four (37%) studies only reported a mortality rate within the first 30 days, another four (37%) only reported a mortality rate within the first year, and three (27%) reported both. The median mortality rate at 1 month was 14% (IQR 12%,32%, n=7), and the median mortality rate at one year was 24% (IQR 23%, 54%, n=7) Nine (60%) studies reported causes of mortality. In all nine of these studies, respiratory failure was the leading cause of death at each time point of analysis.

Conclusion : This meta-analysis is limited by the low quality and observational nature of available research focusing on mortality in elderly patients with cervical spinal cord injury. Nevertheless, it appears that respiratory failure is a driving force behind these patients dying in both the short term and long term setting. Further research is needed to better understand this phenomenon and the impact of surgical intervention and aggressive respiratory care, if any, on this complication.