BACKGROUND: Fear of occult cervical spine injury in patients who have experienced blunt trauma compels clinicians to liberally order cervical spine radiographs. Consequently, a high percentage of normal radiographs are obtained at a high monetary cost. The National Emergency X-Radiography Utilization Study (NEXUS) was conducted to validate a simple clinical prediction guide used to identify blunt trauma patients at low risk for cervical spine injury.
POPULATION STUDIED: All blunt trauma patients who had cervical x-rays in 21 emergency departments across the country were enrolled in this investigation. The study sites were located in hospitals that varied in size, level of activity of the emergency department, level of care, and other factors. The patients ranged in age from 1 year to 101 years; the mean age was 37 years.
STUDY DESIGN AND VALIDITY: This was a prospective validation of a clinical prediction guide. This guide rules out the need for cervical radiography if 5 clinical criteria are fulfilled: (1) absence of tenderness at the posterior midline of the cervical spine, (2) absence of a focal neurologic deficit, (3) a normal level of alertness, (4) no evidence of intoxication, and (5) absence of clinically apparent pain that might distract the patient from the pain of a cervical spine injury. Clinicians treating blunt trauma patients prospectively completed a study data form that included assessment of the 5 clinical criteria and demographic information. Each patient received cervical x-rays at the discretion of the treating physician, who was instructed to use his usual criteria for obtaining radiographs. Designated radiologists at each study site formally interpreted all radiographs while being blinded to the clinical assessment of the treating physician. The statistical analysis included basic performance measures of the decision instrument (sensitivity, specificity, positive predictive value, and negative predictive value). Two limitations of the study are that the 5 clinical criteria are open to some individual interpretation, and that “blunt trauma” was not defined. The treating clinicians were also not blinded to the decision instrument being tested.
OUTCOME MEASURED: The primary outcomes were the sensitivity, specificity, positive predictive value, and negative predictive value of the clinical prediction guide for the detection of radiographically confirmed cervical spine injury.
RESULTS: of 34,069 patients who underwent cervical spine radiography, 818 (2.4%) had documented cervical spine injuries. Although the clinical prediction guide failed to identify 8 of these injuries, only 2 were classified as clinically significant. The negative predictive value of the 5 clinical criteria for patients who did not have clinically significant injuries was 99.9% (95% confidence interval, 99.8%-100%). In other words, blunt trauma patients who screen negative for all 5 clinical criteria have a 99.9% chance of not having a clinically significant injury. The decision instrument identified 4306 patients (12.6%) as having low probability of cervical spine injury. These patients could have been spared radiographic evaluation.
The NEXUS study successfully validates a clinical prediction guide that identifies blunt trauma patients at low risk for cervical spine injury.
Blunt trauma patients who satisfy the 5 clinical criteria do not need cervical spine radiographs.