1Wake Forest University School of Medicine, Winston-Salem, NC
2Virginia Tech – Wake Forest University Center for Injury Biomechanics, Blacksburg, VA, Winston-Salem, NC
Trauma in the US's increasingly aged population will pose medical, engineering, and legislative challenges in the coming decade. This study sought to identify the age threshold of maximal risk for patients with the three most common isolated types of head injuries from motor vehicle crashes (MVCs).
Receiver-operator characteristic analysis was used to identify the quantitative age threshold associated with increased mortality for the three most common MVC-induced types of head injuries. For each injury, an algorithm using multivariable logistic regression modeling was implemented to examine mortality as a function of age, adjusted for the GCS motor score and patient gender. The age threshold that maximized the area under the receiver operator characteristic curve (AUROC) was identified and the curve examined. The increased adjusted odds ratio (AOR) for death associated with each threshold was estimated along with 95% confidence intervals.
Data used was from the American College of Surgeons National Trauma Data Bank (NTDB) version 7, Motor Vehicle Crash cases from Jan 1, 2001 to Dec 31, 2006. Three types of head injuries were of a sufficiently high incidence and severity level to be included in the study; the AIS 140684.3 (Cerebrum, Subarachnoid Hemorrhage, n=499), AIS 140650.4 (Cerebrum, Subdural Hematoma NFS, n=273), and AIS 140629.4 (Hematoma/Hemorrhage, Not Further Specified, n=123). The age thresholds are 58 (AOR=4.12, 95% CI 1.21-14.07, p=0.024), 54 (AOR=4.71, 95% CI 1.08-20.46, p=0.039) and 47 (AOR=15.44, 95% CI 2.94-81.2, p=0.001), respectively. Maximal AUROC values ranged from 0.89-0.93. This data along with data on injury mechanism has been used to provide information on the ideal 'threshold' beyond which age becomes an important factor for these three types of head injuries.
This is the first study to quantitatively estimate the mortality threshold age for common isolated head injuries. This study has potential implications in the arena of safety design for the elderly, automated crash notification, and auto safety legislation.