Pedestrians injured by automobiles: risk factors for cervical spine injuries.

BACKGROUND

Diagnosis of cervical spine injuries (CSI) in multitrauma patients, especially in the presence of head trauma, can be difficult. Identification of risk factors associated with CSI can help avoid missed or delayed diagnosis.

METHODS

Trauma registry study of pedestrian injuries caused by being hit by an automobile. Data abstracted for each patient included age, gender, Glasgow Coma Score on admission, Injury Severity Score, Abbreviated Injury Scale (AIS) for each body area, level of cervical spine injuries, and associated injuries. The incidence of spine injuries was derived for 4 age groups (14 years and younger, 15 to 55 years, 56 to 65 years, and older than 65 years). Logistic regression analysis was performed to identify risk factors associated with CSI.

RESULTS

There were 8,401 pedestrian injuries caused by automobiles, and 178 patients (2.1%) had CSI. Incidence of CSI increased with age (0.3% in the age group 14 years and younger, 2.2% in the group 15 to 55 years, 3.7% in the group 56 to 65 years, and 4.4% in the group older than 65 years). Using the youngest age group (14 years and younger) as reference, relative risk of CSI in the other groups was 7.0, 12.1, and 14.2, respectively (p < 0.0001). Patients with severe head trauma (AIS > 3) were significantly more likely to have CSI than patients with less severe head injuries (AIS <or= 3) (1.3% versus 9.0%, p < 0.0001). In the group of 5,040 injuries with no head trauma, there was not even a single case of CSI. Stepwise logistic regression analysis identified age, severe head injury (AIS > 3), severe chest trauma (AIS > 3), pelvic fracture, and femur fracture as independent risk factors for CSI.

CONCLUSIONS

Incidence of CSI after injuries to pedestrians hit by automobiles increases with age and severity of head trauma. Age, severe head trauma, severe chest trauma, pelvic fracture, and femur fractures are independent predictors of CSI.