Mortality Factors Regarding the Injury Severity Score in Elderly Trauma Patients

Abstract

Mortality of trauma patients is strongly associated with Injury Severity Score (ISS). However, the interaction between ISS and age has not been studied extensively. We evaluated ISS in different age groups in relation to mortality rate. This was a retrospective review of 955 trauma patients who visited Mackay Memorial Hospital during January–December 2009. Age, sex, emergency department (ED) stay time, hospital stay time, out-of-hospital cardiac arrest, in-hospital cardiac arrest, ED survival rate, emergency operation, and mortality were analyzed. Patients were separated into two groups by age below or above 65 years, and hospital courses and mortality rate were compared. Nine hundred and fifty-five trauma patients visited our ED in 2009: 212 in the aged group (99 male patients; 46.7%) and 743 in the young group (472 male patients; 63.5%). The mean age of the elderly group was 77 ± 8 years (mean ± standard deviation), and 38 ± 16 years in the young group. Mean ISS was 12 ± 12 in the elderly group and 10 ± 13 in the young group. The mean ED stay time was 2.9 ± 3.8 hours for the elderly group and 3.0 ± 4.6 hours for the young group. One hundred and sixty-three patients were admitted and the mean hospital stay time was 12.7 ± 13.6 days in the elderly group, whereas 559 patients were admitted and the mean hospital stay time was 9.9 ± 13.7 days in the young group (p = 0.018). The mortality rate among hospitalized patients was 3.1% in the elderly group and 2.9% in the young group. On receiver operating characteristic curve analysis, the optimal cut-off ISS for mortality rate among young patients (area under the curve: 0.899) and elderly patients (area under the curve: 0.782) was 17 (sensitivity: 81.3%; specificity: 88.7%) and 14 (sensitivity: 80%; specificity: 82.3%), respectively. The elderly group seemed to have no significant difference from the younger group for mortality rate, ED stay time and hospital stay time. In the elderly group, lower ISS predicted a higher mortality than in the younger group.