Specificity of cervical spine radiography: Importance of clinical scenario

Knowledge of the sensitivity and specificity of relevant imaging studies is critical to the design of cost-effective clinical algorithms. In developing a cost-effectiveness analysis for cervical spine injuries, we encountered a paucity of data on the specificity of plain radiographs for the detection of cervical spine fracture. Therefore, we measured the specificity of cervical spine radiography in trauma patients at various levels of risk for fracture. A random sample of trauma patients who underwent cervical spine radiography were selected for each of several clinical scenarios. The numbers of false-positive and true-negative studies were determined from radiology records, and specificity was calculated. Specificity ranged from a low of 72% in patients who sustained a pelvic fracture from a fall to a high of 96% in all patients who sustained nonpenetrating trauma. In patients at high risk for cervical spine fracture, the specificity of radiography was relatively low. Understanding of radiographic specificity can aid in the development of imaging guidelines.