Income and risk of mortality after spinal cord injury

Objective: To evaluate the association of household income and formal education with risk of mortality after spinal cord injury (SCI).

Design: Cohort study.

Setting: Twenty hospitals designated as Model SCI Systems of care in the United States.

Participants: Adults (N=8027) with traumatic SCI, seen in one of the Model SCI Systems, who had at least 1 follow-up assessment between 1995 and 2006. All participants were at least 1 year postinjury at the time of assessment. There were 57,957 person-years and 1036 deaths. The follow-up period started with the first assessment between 1995 and 2006 and went until either the date of death or March 2009.

Interventions: Not applicable.

Main outcome measures: Mortality status was determined by routine follow-up supplemented by using the Social Security Death Index. A logistic regression model was developed to estimate the chance of dying in any given year.

Results: Educational status and income were significantly predictive of mortality after adjusting for age, sex, race, and severity of injury. Compared with those with household income of $75,000 or greater, the odds of mortality was greater for those who had income between $25,000 and $75,000 (1.61) and still higher for those with less than $25,000 a year (2.41). Life expectancy differed more as a function of household income than the economic subscale of the Craig Handicap Assessment and Reporting Technique.

Conclusion: There was a clear gradation in survival based on familial income (high, middle, low), not just an effect of the lowest income.