Unnecessary diagnostic imaging leads to higher costs, longer emergency department stays, and increased patient exposure to ionizing radiation. We sought to prospectively derive and validate two decision instruments (DIs) for selective chest computed tomography (CT) in adult blunt trauma patients.
Methods and Findings
From September 2011 to May 2014, we prospectively enrolled blunt trauma patients over 14 y of age presenting to eight US, urban level 1 trauma centers in this observational study. During the derivation phase, physicians recorded the presence or absence of 14 clinical criteria before viewing chest imaging results. We determined injury outcomes by CT radiology readings and categorized injuries as major or minor according to an expert-panel-derived clinical classification scheme. We then employed recursive partitioning to derive two DIs: Chest CT-All maximized sensitivity for all injuries, and Chest CT-Major maximized sensitivity for only major thoracic injuries (while increasing specificity). In the validation phase, we employed similar methodology to prospectively test the performance of both DIs.
We enrolled 11,477 patients—6,002 patients in the derivation phase and 5,475 patients in the validation phase. The derived Chest CT-All DI consisted of (1) abnormal chest X-ray, (2) rapid deceleration mechanism, (3) distracting injury, (4) chest wall tenderness, (5) sternal tenderness, (6) thoracic spine tenderness, and (7) scapular tenderness. The Chest CT-Major DI had the same criteria without rapid deceleration mechanism. In the validation phase, Chest CT-All had a sensitivity of 99.2% (95% CI 95.4%–100%), a specificity of 20.8% (95% CI 19.2%–22.4%), and a negative predictive value (NPV) of 99.8% (95% CI 98.9%–100%) for major injury, and a sensitivity of 95.4% (95% CI 93.6%–96.9%), a specificity of 25.5% (95% CI 23.5%–27.5%), and a NPV of 93.9% (95% CI 91.5%–95.8%) for either major or minor injury. Chest CT-Major had a sensitivity of 99.2% (95% CI 95.4%–100%), a specificity of 31.7% (95% CI 29.9%–33.5%), and a NPV of 99.9% (95% CI 99.3%–100%) for major injury and a sensitivity of 90.7% (95% CI 88.3%–92.8%), a specificity of 37.9% (95% CI 35.8%–40.1%), and a NPV of 91.8% (95% CI 89.7%–93.6%) for either major or minor injury. Regarding the limitations of our work, some clinicians may disagree with our injury classification and sensitivity thresholds for injury detection.
We prospectively derived and validated two DIs (Chest CT-All and Chest CT-Major) that identify blunt trauma patients with clinically significant thoracic injuries with high sensitivity, allowing for a safe reduction of approximately 25%–37% of unnecessary chest CTs. Trauma evaluation protocols that incorporate these DIs may decrease unnecessary costs and radiation exposure in the disproportionately young trauma population.
In this multicenter prospective observational study, Robert Rodriguez and colleagues derive and validate two decision instruments for identifying which blunt trauma patients should receive chest CT and which can avoid unnecessary imaging.
Trauma—a serious injury to the body caused by violence or an accident—is a major global health problem. Every year, events that include traffic collisions, falls, and burns cause injuries that kill more than 5 million people (9% of annual global deaths). Road traffic accidents alone cause about 1.24 million deaths per year. In many countries, including the US, trauma is the number one killer of individuals aged 1–46 years. Chest injuries—damage to the chest wall such, as rib fractures, or damage to the lungs, heart, airways, or major blood vessels within the chest—are responsible for a quarter of trauma deaths. Chest injuries can be penetrating or blunt. Penetrating injuries (for example, stabbings) are generally easy to diagnose and usually require surgery. Blunt injuries, which are often the result of falls or road accidents, can often be managed with relatively simple interventions such as mechanical ventilation but can be hard to diagnose.
Why Was This Study Done?
Computed tomography (CT) is often used to evaluate patients with blunt trauma. This imaging procedure uses special X-ray equipment and computer programs to create two-dimensional and three-dimensional pictures of the organs, bones, and other tissues of the body. CT is good at providing information about internal injuries, and many trauma centers now routinely examine victims of major trauma using head-to-pelvis CT. However, chest CT exposes patients to radiation doses that may increase their risk of cancer. Moreover, chest CT is expensive and does not always provide much additional information if completed after a normal chest X-ray. To reduce the costs and radiation risks of unnecessary CT imaging after blunt trauma, in this prospective observational study, the researchers develop and validate two clinical decision instruments that identify patients with blunt chest injuries, thereby allowing clinicians to forego CT in patients who do not meet the decision instrument criteria for blunt injuries.
What Did the Researchers Do and Find?
The researchers had clinicians record the presence or absence of 14 candidate clinical criteria in 6,002 patients aged over 14 years attending eight US trauma centers with blunt trauma before viewing chest CT results and categorizing the injuries seen as major or minor using a preset classification scheme. They then derived two clinical decision instruments from these data using a statistical method called recursive partitioning. The Chest CT-All decision instrument, which maximized sensitivity (the ability to correctly identify people with a condition) for either major and minor chest injuries, consisted of seven clinical criteria including an abnormal x-ray, rapid deceleration mechanism (trauma caused by, for example, a road collision occurring at more than 40 mph), and bone tenderness (pain that occurs when an area is touched) in the chest. The Chest CT-Major instrument, which maximized sensitivity for only major chest injuries, consisted of the same criteria without rapid deceleration mechanism. Applied to 5,475 additional patients who presented with blunt trauma, the Chest CT-All instrument correctly identified 95.4% of patients with a major or minor blunt chest injury as having an injury (a sensitivity of 95.4%) and 25.5% of patients without a major or minor injury as not having an injury (a specificity of 25.5%); the instrument had a negative predictive value (NPV) of 93.9% (a patient judged injury-free using the instrument had a 93.9% probability of being injury-free). The Chest CT-Major instrument had a sensitivity of 99.2%, specificity of 31.7%, and NPV of 99.9% for major injuries.
What Do These Findings Mean?
These findings describe two decision instruments that detect clinically important blunt chest injuries with high sensitivity. Because the use of these instruments allows clinicians to identify virtually everyone who has this type of injury, clinicians can forego CT in patients who do not exhibit any of the decision instrument criteria for blunt chest injury. That is, clinicians can safely use physical examination and history findings, instead of imaging, to rule out blunt chest injury in many patients attending a trauma center. Limitations of this study include the criteria used to classify injuries as minor or major. Moreover, these decision instruments should be used to augment rather than replace clinical judgment and should not be used to evaluate patients younger than 15 years old. Importantly, however, use of these decision instruments could reduce the number of unnecessary chest CTs undertaken in trauma centers by up to a third, thus reducing costs and radiation exposure in people with trauma.
This list of resources contains links that can be accessed when viewing the PDF on a device or via the online version of the article at http://dx.doi.org/10.1371/journal.pmed.1001883.
This study is further discussed in a PLOS Medicine
Perspective by Emmanuel Lagarde
The World Health Organization provides information in several languages about injuries around the world; its Guidelines for Essential Trauma Care seeks to set achievable standards for trauma treatment services that could realistically be made available to almost every injured person in the world
The US National Institute of General Medical Sciences has a factsheet on trauma
The National Trauma Institute, a not-for-profit organization that supports research on trauma, provides US trauma statistics, trauma survivor stories, and links to other organizations in the US that provide information on trauma
Wikipedia has pages on major trauma, chest injury, and computed tomography (note that Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
MedlinePlus provides links to additional information about trauma and about chest injuries and disorders (in English and Spanish)