It is not uncommon for the standard of care to be dictated by those who speak the loudest rather than a representative sample of best medical practice. This is certainly the case with the inclusion of whole-body CT scans in the initial management of patients presenting to the Emergency Department with traumatic complaints. Known colloquially as the trauma pan-scan, this global irradiation has become a significant part of the primary survey in many trauma centers across the US. For critically ill trauma patients in whom the clinical exam is unreliable, the introduction of the CT scan has been invaluable. What benefits do total body radiological evaluations provide for the clinically stable, cognitively present patient with minor injuries?
Recently published studies have promoted the pan-scan’s utility, claiming that those patients initially exposed to a total body irradiation fared significantly better than patients who underwent selective scanning as per the judgment of the treating physician (1,2,3,4). The most notable of these studies was published in the Lancet in 2009 by Huber-Wagner et al (1). In this retrospective analysis the authors examined 4621 trauma patients enrolled in the German Trauma Society’s trauma registry from 2002-2004. The authors compared the mortality rates in those who received early empiric whole-body CT scans to those who received selective scanning. The authors utilized both the trauma and injury severity score (TRISS) and the revised injury severity classification (RISC), in an attempt to control for the retrospective, non-randomized nature of this trial. Both these scores attempt to predict the severity of injury using patient factors as well as anatomical injuries as defined by the abbreviated injury scale (AIS).
The authors found a significant reduction in mortality when compared to the value predicted by both the TRISS and RISC scores (ARR of 5.9% and 3.1% respectively), in the patients who received whole-body CT scans. Conversely the patients who received selective scanning were found to have no difference between their actual mortality and that predicted by the TRISS and RISC assessment scores. Furthermore when the authors attempted to control for age, hospital site, and date of presentation through logistic regression, whole-body CT scans remained a statistically significant predictor of reduced mortality (OR of 0.66, 95%-CI 0.50–0.86)(1).
Since the publication of this paper, a number of additional retrospective analyses have been conducted demonstrating similar results. The largest again penned by Huber-Wagner et al was a re-analysis of their trauma registry published in 2013 in PLoSE One (3), which confirmed their initial findings in a much larger cohort. A 2014 meta-analysis found analogous results (4).
The causal inference these trials hope to make is that the whole-body CT in the undifferentiated, well-appearing trauma patient saves lives. There are of course significant methodological problems that prevent us from drawing such a causative conclusion. Due to each trial’s retrospective, non-randomized design, we are unable to truly assess the similarity of the groups we are comparing. As such the potential for the introduction of bias into the results is incredibly high.
Huber-Wagner et al employed a technique known as the standardized mortality ratio (SMR) in an attempt to compensate for this potential bias (1). This involves comparing the actual mortality to the predicted mortality. Numbers less than 1 denote an actual mortality that was lower than what is predicted. Of note, in this form of analysis, there is no direct comparison between whole-body CT and controls. The SMR assumes the validity of whatever prognostic scoring system was used to predict the acuity of the patients examined. In this case the authors used both the TRISS and the RISC scores. Both of these systems utilize the injury severity score (ISS) as a large component of the resulting score. Many authors have written questioning the validity of the ISS (5) scoring system. Most recently, a January 2016 article published in Annals of Emergency Medicine by Gupta et al described the phenomenon of ISS inflation due directly to the Trauma Pan-Scan (6).
The ISS scoring system is based purely on the anatomic definition of injury. Using the anatomic injury scores originally proposed in JAMA in 1971 as a means of assessing automotive-related injuries (7), the ISS assigns a numeric score (0-6) for each anatomic area. This score then is squared and the squared numbers are then summed to give the resulting ISS. ISS ranges from 0-72. Since this is purely an anatomically defined score, patients who undergo whole-body CT are far more likely to have clinically insignificant injuries detected by these unnecessary scans. Given the exponential nature of the ISS, these findings can artificially inflate the resulting score. This shifts a healthier cohort into a more severe ISS level creating the illusion of improved outcomes.
To demonstrate the reality of this phenomenon, Gupta et al performed a secondary analysis of a trial originally published in Annals of Emergency Medicine in 2011. In the original cohort also by Gupta et al, the authors examined blunt trauma patients presenting to an academic Emergency Department who warranted trauma team activation (8). After examining the patients, the attending Emergency Physician and Trauma Surgeon were asked what anatomic areas they would want to image for further diagnostic evaluation. Results of the whole body CT were compared to whether the imaging was desired by the Emergency Physicians and Trauma Surgeons respectively. An undesired scan was defined as a component of the whole body CT that either the Emergency Physician, Trauma Surgeon or both stated was an unnecessary part of the radiologic evaluation. The original study enrolled 701 patients, of which, 600 (86%) received a whole body CT. Of the total 2,615 scans, 992 were undesired by at least one attending physician. Out of the 992 undesired scans 3 (0.3%) abnormalities were found that led to a predefined important intervention, though even these were questionable (for example 9 rib fractures were identified on CXR and 10 were observed on chest CT) (8).
Gupta et al examined the subset of patients from their original cohort who underwent undesired imaging where non-critical injuries were discovered. Using these 92 patients, the authors calculated what their ISS would have been if these undesired scans were not obtained. When compared to their actual ISS, the authors found a 50% reduction in the ISS score (6). This amplification of the ISS is an obvious and potent confounder in any non-randomized cohorts that attempt to utilize trauma injury scores to account for variations in case-mix and acuity level.
In 2006 Salim et al published the results of a prospective trial examining the utility of the pan-scan in clinically evaluable trauma patients (9). The authors enrolled 592 patients with no outward signs of trauma, who were clinically evaluable on presentation. They claimed to have found a multitude of injuries on CT that would have otherwise gone undiagnosed. In fact the authors cite that these findings changed management in 18.9% of patients. These results are disquieting to say the least. That is until one actually reads what injuries were identified. Among the injuries the authors discovered, 26 cervical spine fractures and 89 rib fractures all of which by their reports were asymptomatic. This of course flies in the face of clinical experience and multiple cohorts documenting the reliability of physical exam in the clearance of the cervical spine and costal injuries (10,11,12,13,14). In the discussion section of the article, Dr. James Tyburski questions this very implausibility;
“… Regarding the CT scan of the cervical spine, there were 30 patients, or 5.1%, with fractures and/or dislocation subluxations in the mechanism group vs 24, or 5.9%, in the group that had an unreliable physical exam. This implies that the physical exam was basically useless in the evaluation of the cervical spine, so I want to be clear here. There were no symptoms, pain, or physical signs, tenderness or anything else like that, etc, in these 30 patients that were awake and fully evaluable? Can you comment on this lack of sensitivity in the evaluation of the cervical spine, as this would be at odds with several trauma care guidelines by other organizations?…
… Regarding the CT scans of the chest, there were 89 rib fractures in the mechanism group alone. And again this implies that none of these patients had pain or tenderness over these ribs. If they did, then that would imply possibly an abnormal physical exam, if it was a physical abdominal exam for their lower rib fractures. Can you comment about that?”
Dr. Salim’s response:
“In terms of pain in the cervical spine, we didn't really address whether they had pain. We were just looking to see if they had any outward signs of trauma. Typically we are just looking at that patient who looks like they don't have anything wrong. It is the typical patient that the ER physician just wants to send home from the ER.”
This exchanges highlights the curious nature of the clinically evaluable patient. Essentially Salim et al examined the efficacy of whole-body CT as a costly and burdensome replacement for physical exam.
The implication when reviewing this literature is that well appearing, evaluable patients presenting to the Emergency Department may be harboring clinically occult, life threatening injuries undetectable by a standard physical exam. And yet this interpretation is based off methodologically flawed retrospective analyses and prospective data sets in which the physical exam was all but neglected. More importantly this ignores the multitude of clinical decision instruments, derived and validated from high quality prospective data, demonstrating that imaging can be avoided using simple components from a history and physical exam (10,11,12,13,14,15). Randomized data is required to truly assess whether the whole-body CT is beneficial in the workup of the undiagnosed trauma patient. One such trial is underway and its results are urgently needed (16). But even if it shows a small benefit in detecting clinically meaningless injuries we must ask ourselves, what is the cost? How many patients do we have to expose to harmful radiation to find one additional rib fracture? What portion of these injuries would remain occult during a reasonable period of observation? How does this overzealous imaging strategy affect the flow of the rest of the department? What about the remainder of our patients, the ones who may truly require an emergent CT who are continually bumped in favor of the endless trauma alerts? There is a cost to all our actions and it behooves us to consider them carefully. No matter who is yelling the loudest.
- Huber-Wagner, S., Lefering, R., Qvick, L.M., and Working Group on Polytrauma of the German Trauma Society. Effect of whole-body CT during trauma resuscitation on survival: a retrospective, multicentre study. Lancet. 2009; 373: 1455–1461
- Hutter M., Woltmann A., Hierholzer C., et al: Association between a single-pass whole-body computed tomography policy and survival after blunt major trauma: a retrospective cohort study. Scand J Trauma Resusc Emerg Med 2011; 19: pp. 73
- Huber-Wagner S, Biberthaler P, Haberle S, Wierer M, Dobritz M, Rummeny E, van Griensven M, Kanz KG, Lefering R: Whole-body CT in haemodynamically unstable severely injured patients – a retrospective. multicentre study. PLoS One 2013, 8(7):e68880.
- Caputo ND, Stahmer C, Lim G, Shah K. Whole-body computed tomographic scanning leads to better survival as opposed to selective scanning in trauma patients: a systematic review and meta-analysis. J Trauma Acute Care Surg. 2014;77(4):534-9.
- Champion, H.R. Trauma Scoring. Scandinavian Journal of Surgery March 2002 91 no. 1 12-22
- Gupta M, Gertz M, Schriger DL. Injury Severity Score Inflation Resulting From Pan-Computed Tomography in Patients With Blunt Trauma. Ann Emerg Med. 2016;67(1):71-75.e3.
- American Medical Association Committee on the Medical Aspects of Automotive Safety: Rating the severity of tissue damage: The abbreviated scale. JAMA 1971;215:277
- Gupta M., Schriger D.L., Hiatt J.R., et al: Selective use of computed tomography compared with routine whole body imaging in patients with blunt trauma. Ann Emerg Med 2011; 58: pp. 407-416.e15
- Salim A, Sangthong B, Martin M, Brown C, Plurad D, Demetriades D. Whole Body Imaging in Blunt Multisystem Trauma Patients Without Obvious Signs of Injury: Results of a Prospective Study. Arch Surg. 2006;141(5):468-475. doi:10.1001/archsurg.141.5.468.
- Hoffman JR, Mower WR, Wolfson AB, Todd KH, Zucker MI. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. National Emergency X-Radiography Utilization Study Group. N Engl J Med. 2000;343(2):94-9.
- Stiell IG, Clement CM, Mcknight RD, et al. The Canadian C-spine rule versus the NEXUS low-risk criteria in patients with trauma. N Engl J Med. 2003;349(26):2510-8.
- Stiell IG, Clement CM, Rowe BH, et al. Comparison of the Canadian CT Head Rule and the New Orleans Criteria in patients with minor head injury. JAMA. 2005;294(12):1511-8.
- Rodriguez RM, Anglin D, Langdorf MI, et al. NEXUS chest: validation of a decision instrument for selective chest imaging in blunt trauma. JAMA Surg. 2013;148(10):940-6.
- Rodriguez RM, Langdorf MI, Nishijima D, et al. Derivation and validation of two decision instruments for selective chest CT in blunt trauma: a multicenter prospective observational study (NEXUS Chest CT). PLoS Med. 2015;12(10):e1001883.
- Rostas J, Cason B, Simmons J, Frotan MA, Brevard SB, Gonzalez RP. The validity of abdominal examination in blunt trauma patients with distracting injuries. J Trauma Acute Care Surg. 2015;78(6):1095-100 .
- Sierink JC, Saltzherr TP, Beenen LF, et al. A multicenter, randomized controlled trial of immediate total-body CT scanning in trauma patients (REACT-2). BMC Emerg Med. 2012;12:4.