The impact of co-morbidities on age-related differences in mortality after acute traumatic spinal cord injury

Despite the shift in demographics of spinal cord injury (SCI) due to an aging population, relatively little has been reported regarding the effect of age on outcomes after SCI. This study examines the potential confounding effect of co-morbidities on the age-related differences in the hospital mortality following acute traumatic SCI. All consecutive patients with SCI who were admitted to our spine center from 1996 to 2007 were included. Co-morbidities were classified using the Charlson Co-morbidity Index (CCI), Cumulative Illness Rating Scale, and the number of ICD-9 codes. Major potential confounders included age, gender, co-morbidity, and level and severity of SCI. There were 217 males and 80 females with ages from 15 to 96 years. Most patients had an incomplete cervical SCI following falls or motor vehicle accidents. The mean in-hospital mortality rate was 5.7%. Using univariate analyses, older age, relevant pre-existing medical conditions, and motor complete SCI were major risk factors for in-hospital death after acute SCI. Among the three co-morbidity assessments, the CCI was the most reliable co-morbidity index for prediction of hospital mortality in SCI patients after controlling for age in the Cox proportional hazard modeling. In addition, the CCI appears to be a major confounder, which accounts for the majority of age-related differences in mortality following SCI. Our findings have implications for future clinical trials of therapies for adult patients with acute SCI and for management strategies of elderly individuals with SCI.