Rational thinking in chest CT
We covered this when the article was released early, but now is the official publication, and many of you were not with EM Topics several months back. This article is helpful.
To determine which patients with blunt trauma need chest CT, the NEXUS CT chest rule may help. In this study, if one criterion (excluding abnormal CXR) was present, it was worth discussing the risk of CT vs the very small risk of clinically major injury (1.1% prevalence). But if the CXR was abnormal (13% prevalence major injury) or there was >1 NEXUS criterion (~3% prevalence major injury), the risk of CT was warranted.
You can avoid the predictable trauma surgery approach to imaging, which is scan everything. The NEXUS CT Chest clinical decision instrument can allow you to safely scan selectively if the CXR is normal and only one NEXUS criterion is present.
Dr. Michelle Lin with ALiEM did a fantastic review of the NEXUS CT Chest rule and interviewed author, Dr. Rodriguez.
Acad Emerg Med. 2016 Aug;23(8):863-9. doi: 10.1111/acem.13010. Epub 2016 Aug 1.
Prevalence and Diagnostic Performance of Isolated and Combined NEXUS Chest CT Decision Criteria.
Raja AS1, Mower WR2, Nishijima DK3, Hendey GW4, Baumann BM5, Medak AJ6, Rodriguez RM7.
1Department of Emergency Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA.
2Department of Emergency Medicine, University of California, Los Angeles, CA.
3Department of Emergency Medicine, University of California, Davis, CA.
4Department of Emergency Medicine, San Francisco Fresno Medical Education Program, San Francisco, CA.
5Department of Emergency Medicine, Cooper Medical School of Rowan University, Camden, NJ.
6Department of Emergency Medicine, University of California at San Diego School of Medicine, San Diego, CA.
7Department of Emergency Medicine, University of California, San Francisco, CA.
The use of chest computed tomography (CT) to evaluate emergency department patients with adult blunt trauma is rising. The NEXUS Chest CT decision instruments are highly sensitive identifiers of adult blunt trauma patients with thoracic injuries. However, many patients without injury exhibit one of more of the criteria so cannot be classified “low risk.” We sought to determine screening performance of both individual and combined NEXUS Chest CT criteria as predictors of thoracic injury to inform chest CT imaging decisions in “non-low-risk” patients.
This was a secondary analysis of data on patients in the derivation and validation cohorts of the prospective, observational NEXUS Chest CT study, performed September 2011 to May 2014 in 11 Level I trauma centers. Institutional review board approval was obtained at all study sites. Adult blunt trauma patients receiving chest CT were included. The primary outcome was injury and major clinical injury prevalence and screening performance in patients with combinations of one, two, or three of seven individual NEXUS Chest CT criteria.
Across the 11 study sites, rates of chest CT performance ranged from 15.5% to 77.2% (median = 43.6%). We found injuries in 1,493/5,169 patients (28.9%) who had chest CT; 269 patients (5.2%) had major clinical injury (e.g., pneumothorax requiring chest tube). With sensitivity of 73.7 (95% confidence interval [CI] = 68.1 to 78.6) and specificity of 83.9 (95% CI = 83.6 to 84.2) for major clinical injury, abnormal chest-x-ray (CXR) was the single most important screening criterion. When patients had only abnormal CXR, injury and major clinical injury prevalences were 60.7% (95% CI = 52.2% to 68.6%) and 12.9% (95% CI = 8.3% to 19.4%), respectively. Injury and major clinical injury prevalences when any other single criterion alone (other than abnormal CXR) was present were 16.8% (95% CI = 15.2% to 18.6%) and 1.1% (95% CI = 0.1% to 1.8%), respectively. Injury and major clinical injury prevalences among patients when two and three criteria (not abnormal CXR) were present were 25.5% (95% CI = 23.1% to 28.0%) and 3.2% (95% CI = 2.3% to 4.4%) and 34.9% (95% CI = 31.0% to 39.0%) and 2.7% (95% CI = 1.6% to 4.5%), respectively.
We recommend that clinicians check for the six clinical NEXUS Chest CT criteria and review the CXR (if obtained). If patients have one clinical criterion (other than abnormal CXR), they will have a very low risk of clinically major injury. We recommend that clinicians discuss the potential risks and benefit of chest CT in these cases. The risks of injury and major clinical injury rise incrementally with more criteria, rendering the risk/benefit ratio toward performing CT in most cases. If the patient has an abnormal CXR, the risks of major clinical injury and minor injury are considerably higher than with the other criteria-chest CT may be indicated in cases requiring greater anatomic detail and injury characterization.
© 2016 by the Society for Academic Emergency Medicine.
PMID: 27163732 [PubMed – in process]