Trends in life expectancy after spinal cord injury

Abstract

Objective: To investigate whether there have been improvements in survival after spinal cord injury (SCI) over time, both in the critical first 2 years after injury and in the longer term.

Design: Pooled repeated observations analysis of person-years. For each person-year, the outcome variable is survival and mortality, and the explanatory variables include age, level and grade of injury, and calendar year (the main focus of the analyses). The method can be viewed as a generalization of proportional hazards regression.

Setting: Model spinal cord injury systems and hospital SCI units across the United States.

Participants: Persons (N=30,822) admitted to a Spinal Cord Injury Model Systems facility a minimum of 1 day after injury. Only persons over 10 years of age and known not to be ventilator dependent were included. These persons contributed 323,618 person-years of data, with 4980 deaths, over the 1973 to 2004 study period.

Interventions: Not applicable.

Main outcome measure: Survival.

Results: Other factors being equal, over the last 3 decades there has been a 40% decline in mortality during the critical first 2 years after injury. However, the decline in mortality over time in the post-2-year period is small and not statistically significant.

Conclusions: The absence of a substantial decline in mortality after the first 2 years postinjury is contrary to widely held impressions. Nevertheless, the finding is based on a large database and sensitive analytic methods and is consistent with previous research. Improvements in critical care medicine after spinal cord injury may explain the marked decline in short-term mortality. In contrast, although there have no doubt been improvements in long-term rehabilitative care, their effect in enhancing the life span of persons with SCI appears to have been overstated.