Risk of mortality after spinal cord injury: Relationship with social support, education, and income

Study design: Prospective cohort study. Objective: To identify the association of social support and socioeconomic factors with risk of early mortality among persons with spinal cord injury. Setting: Participants were identified from a large specialty hospital in the Southeastern United States. Methods: Data were collected by mailed survey, and mortality status was ascertained approximately 8 years later. The outcome was time from survey to mortality or censoring. Mortality status was determined using the National Death Index and the Social Security Death Index. There were 224 observed deaths (16.2%) in the full sample (n=1386). Because of missing data, the number of deaths used in the final analysis was 188 (out of 1249 participants). Results: Cox proportional hazards modeling was used to build a comprehensive predictive model. After controlling for biographic and injury-related factors, two of four environmental predictors were retained in the final model including low income and general social support. Years of education and the upsets scale, another aspect of social support, were not retained in the final model. Inclusion of these variables resulted in only modest improvement in the prediction of survival compared with biographic and injury variables alone, as the pseudo-R² increased from 0.121 to 0.134 and the concordance from 0.730 to 0.751. Conclusion: Environmental factors are important predictors of mortality after spinal cord injury.