Object: A rule for identifying patients with traumatic brain injury (TBI) who are at exceptionally low risk of cervical spine injury might be clinically useful. The goal in this study was to research case records to determine whether such a rule would be practicable.
Methods: The Pennsylvania Trauma Outcomes Study database was used to find patients with TBI in whom Glasgow Coma Scale (GCS) scores at admission were 8 or less. Cases of cervical spine injury were identified from diagnostic codes. Associations between these injuries and a variety of clinical variables were tested using chi-square analysis. The probability of a cervical spine injury in these patients was modeled by logistic regression. Decision tree models were constructed and statistical determinants of overlooked cervical spine injury were examined. The prevalence of cervical spine injury among 41,142 cases of TBI was 8%. The mechanism of injury, presence of thoracolumbosacral (TLS) spinal, limb and/or facial fracture, patient age, GCS score at admission, and the presence of hypotension were all factors associated with cervical spine injury. These were incorporated into the following logistic regression model: probability of cervical spine injury = 1/(1 + exp[4.030 - 0.417*mechanism - 0.264*age - 0.678*TLS - 0.299*limb + 0.218*GCS score - 0.231*hypotension - 0.157*facial]). This model yielded a rule for clearance of 28% of cases, with a negative predictive value (NPV) of 97%. Decision tree analysis yielded an easily stated rule for clearance of 24% of cases, with an NPV of 98.2%. The prevalence of overlooked cervical spine injury among all patients with severe TBI was 0.3%; the prevalence of overlooked cervical spine injury among patients in whom it was later diagnosed was 3.9%. Overlooked cervical spine injury was less common among patients with associated TLS fractures (odds ratio 0.453, 95% confidence interval 0.245-0.837).
Conclusions: No acceptable rule for relaxation of vigilance in the search for cervical spine injury among patients with severe TBI has been identified. Levels of provider vigilance and consequent rates of overlooked cervical spine injury can be affected by environmental cues and presumably by other behavioral and organizational factors.