Two new clinical decision instruments (DIs) may allow physicians to rule out chest injury before resorting to computed tomography (CT) scans, avoiding unnecessary chest CT-associated costs and radiation exposure in approximately one-third of blunt trauma patients, according to a study appearing in this week's PLOS Medicine by Dr Robert Rodriguez of the University of California, San Francisco, and colleagues. The researchers describe deriving and validating Chest CT-All, a DI designed to identify both major and minor blunt chest injury, and Chest CT-Major, a DI optimized to identify major chest injuries.
Using data from a cohort of 6,002 blunt trauma patients presenting at eight urban US trauma centers, Rodriguez and colleagues identified 7 clinical criteria (abnormal chest X-ray, rapid deceleration mechanism, distracting injury, chest wall tenderness, sternal tenderness, thoracic spine tenderness, and scapular tenderness) to be used for Chest CT-All. When applied to a validation cohort of 5,475 blunt trauma patients, Chest CT-All was able to correctly identify 95.4% of patients with a major or minor blunt chest injury (sensitivity), and correctly identify 25.5% of the patients as not having a major or minor injury (specificity). The probability that a patient with a negative DI result is injury free (negative predictive value, NPV) for Chest CT-All was 93.9%.
Chest CT-Major includes the same criteria as Chest CT-All, except for rapid deceleration mechanism. In the same validation cohort, Chest CT-Major had a sensitivity of 99.2%, specificity of 31.7%, and NPV of 99.9% for major injuries. The authors note that there may be disagreement about the classification of major and minor injuries, and that differences in injury prevalence between different trauma centers may affect the NPV of the DIs.
Still, these DIs may allow trauma physicians to rule out major and minor blunt trauma injuries on the basis of clinical characteristics and X-ray results, and avoid unnecessary further imaging. The authors say: "Incorporation of these DIs into trauma evaluation protocols may allow for a safe reduction of approximately 25%-37% of non-diagnostic chest CTs, thereby reducing costs and avoiding radiation exposure in the disproportionately young trauma population."
In an accompanying Perspective article, Emmanuel Lagarde of the Université de Bordeaux, France, discusses the harms and costs of overusing diagnostic imaging such as CT scans. "The study by Rodriguez and colleagues is one of too small a number of papers attempting to identify solutions to the twofold concern of CT expansion: costs and exposure to ionizing radiation," writes Lagarde.
Funding: Funded by University of California Center for Health Quality and Innovation (CHQI): 071:2011. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
Rodriguez RM, Langdorf MI, Nishijima D, Baumann BM, Hendey GW, Medak AJ, et al. (2015) Derivation and Validation of Two Decision Instruments for Selective Chest CT in Blunt Trauma: A Multicenter Prospective Observational Study (NEXUS Chest CT). PLoS Med 12(10): e1001883. doi:10.1371/journal.pmed.1001883
Department of Emergency Medicine, The University of California San Francisco
Department of Emergency Medicine, University of California Irvine
Department of Emergency Medicine, The University of California Davis
Department of Emergency Medicine, Cooper Medical School of Rowan University
Department of Emergency Medicine, University of California San Francisco Fresno Medical Education Program
Department of Emergency Medicine, University of California San Diego School of Medicine
Department of Emergency Medicine, Massachusetts General Hospital/Harvard Medical School
The University of California San Francisco
Department of Emergency Medicine, University of California Los Angeles
University of California San Francisco School of Medicine
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