Although chest x-ray (CXR) is often used as a screening tool for thoracic injury in adult blunt trauma assessment, its screening performance is unclear. Using chest CT as the referent standard, we sought to determine the screening performance of CXR for injury.

We analyzed data from the NEXUS Chest CT study, in which we prospectively enrolled blunt trauma patients older than 14 years who received chest imaging as part of their evaluation at nine level I trauma centers. For this analysis, we included patients who had both CXR and chest CT. We used CT as the referent standard and categorized injuries as clinically major or minor according to an a priori expert panel classification.

Of 11,477 patients enrolled, 4501 had both CXR and chest CT; 1496 (33.2%) were found to have injury, of which 256 (17%) were classified as major injury. CXR missed injuries in 818 patients (54.7%), of which 63 (7.7%) were classified as major injuries. For injuries of major clinical significance, CXR had a sensitivity of 75.4% (95% confidence interval [CI] 69.6–80.4%), specificity of 86.2% (95% CI 85.1–87.2%), negative predictive value of 98.3 (95%CI 97.9–98.6%), and positive predictive value of 24.7 (95%CI 22.9–26.7%). For any injury CXR had a sensitivity of 45.3% (95% CI 42.8–47.9%), specificity of 96.6% (95% CI 95.9–97.2%), negative predictive value of 78% (95% CI 77.2–78.8%), and positive predictive value of 86.9% (95% CI 84.5–89.0%). The most common missed major injuries were pneumothorax (30/185; 16.2%), spinal fractures (19/39; 48.7%), and hemothorax (8/70; 11.4%). The most common missed minor injuries were rib fractures (381/836; 45.6%), pulmonary contusion (203/462; 43.9%), and sternal fractures (153/229; 66.8%).

When used alone, without other trauma screening criteria, CXR has poor screening performance for blunt thoracic injury.