Differential survival after traumatic spinal cord injury: evidence from a multi-center longitudinal cohort study in Switzerland

Abstract

STUDY DESIGN Observational cohort study. OBJECTIVES To understand differentials in the force of mortality with increasing time since injury according to key spinal cord injury (SCI) characteristics. SETTING Specialized rehabilitation centers within Switzerland. METHODS Data from the Swiss Spinal Cord Injury (SwiSCI) cohort study were used to model mortality in relation to age, sex, and lesion characteristics. Hazard ratios (HRs) and adjusted survival curves were estimated using flexible parametric survival models of time since discharge from first rehabilitation to death or 30 September 2011, whichever came first. RESULTS 2 421 persons were included that incurred a new TSCI between 1990 and 2011, contributing a total time-at-risk of 19,604 person-years and 376 deaths. Controlling for attained age, sex, decade, and etiology, there was more than a four-fold higher risk of mortality for complete tetraplegia compared to incomplete paraplegia (HR = 4.27; 95% CI 2.72 to 6.69). Survival estimates differed according to SCI characteristics, with differentials steadily increasing with time since injury. CONCLUSION This study provides evidence of disparities in mortality and survival outcomes according to SCI characteristics that increases with increasing time since injury. These results lend support to the hypothesis of a progressive and disproportionate accumulation of allostatic load according to SCI characteristics. Future research should investigate cause-specific mortality for insight into potentially modifiable secondary health conditions contributing to these disparities.