Risk factors for traumatic injury findings on thoracic computed tomography among patients with blunt trauma having a normal chest radiograph.

Hypothesis: We sought to identify risk factors that might predict acute traumatic injury findings on thoracic computed tomography (TCT) among patients having a normal initial chest radiograph (CR).

Design: In this retrospective analysis, Abbreviated Injury Score cutoffs were chosen to correspond with obvious physical examination findings. Multivariate logistic regression analysis was performed to identify risk factors predicting acute traumatic injury findings.

Setting: Urban level I trauma center.

Patients: All patients with blunt trauma having both CR and TCT between July 1, 2005, and June 30, 2007. Patients with abnormalities on their CR were excluded.

Main Outcome Measure: Finding of any acute traumatic abnormality on TCT, despite a normal CR.

Results: A total of 2435 patients with blunt trauma were identified; 1744 (71.6%) had a normal initial CR, and 394 (22.6%) of these had acute traumatic findings on TCT. Multivariate logistic regression demonstrated that an abdominal Abbreviated Injury Score of 3 or higher (P = .001; odds ratio, 2.6), a pelvic or extremity Abbreviated Injury Score of 2 or higher (P < .001; odds ratio, 2.0), age older than 30 years (P = .004; odds ratio, 1.4), and male sex (P = .04; odds ratio, 1.3) were significantly associated with traumatic findings on TCT. No aortic injuries were diagnosed in patients with a normal CR. Limiting TCT to patients with 1 or more risk factors predicting acute traumatic injury findings would have resulted in reduced radiation exposure and in a cost savings of almost $250,000 over the 2-year period. Limiting TCT to this degree would not have missed any clinically significant vertebral fractures or vascular injuries.

Conclusion: Among patients with a normal screening CR, reserving TCT for older male patients with abdominal or extremity blunt trauma seems safe and cost-effective.