Mortality With and Without Whole-Body CT in Severely Injured Children

Background: The choice of imaging modality—the use of whole-body computed tomography (WB-CT) versus a step-wise diagnostic procedure—in injured children is controversial. In this study we availed ourselves of data from the TR-DGU, the trauma registry of the German Society for Trauma Surgery (Deutsche Gesellschaft für Unfallchirurgie), to investigate whether the use of WB-CT improves the outcome.

Methods: The TR-DGU data from the period 2012–2021 were evaluated. A three-stage analysis began with comparison of children with adults aged ≤ 50 years. As a second step, the observed and expected mortality in children with WB-CT was compared with the mortality in children without WB-CT. Finally, predictors of the use of WB-CT were identified so that a propensity score analysis of matched pairs could be performed.

Results: A total of 65 092 patients were included, 4573 children (7%) and 60 519 adults (93%), with differences in accident type and injury pattern. Comparison of the ratio of observed to expected mortality revealed no difference between the two groups of children (standardized mortality ratio 0.97 with WB-CT, 0.95 without WB-CT). In adults, however, there was an advantage for the WB-CT group. The propensity score analysis of 1101 matched pairs showed identical mortality in the two groups (3.9% with WB-CT, 4.0% without WB-CT).

Conclusion: The TR-DGU data show no benefit of WB-CT compared with step-wise diagnosis in the care of severely injured children. In view of the radiation exposure involved, with the danger of inducing malignancy, the benefits and risks of the use of WB-CT in children should be weighed up carefully in team discussions.

The most common cause of death in childhood is trauma, accounting for 19.8% of deaths in children aged 1 to 4 years and 62% in adolescents aged 15 to 19 (1, 2). The appropriate imaging studies for children who have sustained severe trauma is a matter of debate, because rapid and reliable diagnosis is wanted, yet it is presumed that x-ray studies in children are associated with a higher delayed cancer risk than the same studies in adults, particularly with respect to solid tumors, thyroid tumors, and leukemia. There are less dramatic risks that need to be considered as well, such as cataract formation due to ionizing radiation (3, 4, 5).

Diagnostic imaging with multi-slice whole-body computed tomography (WBCT) is advantageous in the care of adults with severe trauma, as has been shown with the aid of data from the DGU Trauma Registry (TR-DGU) of the German Society for Trauma Surgery (DGU) and from other sources (6, 7, 8, 9, 10).

As it has not yet been shown that WBCT in children with severe trauma is advantageous with respect to mortality (11, 12, 13), the use of WBCT for these patients is still debated. Aside from the higher radiation exposure, a further argument against WBCT is that children often have good acoustic conditions for (extended) focused assessment with sonography for trauma (FAST or eFAST). In FAST, sonography is used to examine the various abdominal spaces and the lesser pelvis for free fluid; in eFAST this examination is extended to the chest and heart. Arguments in favor of WBCT include high sensitivity (fewer missed injuries), the lower time requirement, and the ability to image all body cavities in a single session.

In the 2016 edition of the German S3 guideline on polytrauma and the management of severely injured patients, it is stated, without direct evidence but by analogy with the outcomes in adults, that prompt WBCT with a trauma-specific protocol should be performed as part of the diagnostic evaluation of severely injured children (2). In the S2K guideline on polytrauma care in childhood, it is stated that, once life-threatening injuries have been ruled out, either a detailed sonographic re-examination of all regions or else a CT scan should be carried out, depending on the primary findings and if the indication is approved by the acute trauma team. This recommendation accords with the international literature (14, 15, 16).

The question under investigation

In view of the known benefit of WBCT in adults with polytrauma and the often emotional debate concerning CT in children, we addressed the question whether severely injured children stand to benefit from multi-slice WBCT with the aid of data from the TR-DGU.

Methods

This review is in compliance with the publication guideline of the DGU Trauma Registry. Comprehensive information on the TR-DGU can be found on the registry website: www.traumaregister-dgu.de.

The statistical analysis was performed on the TR-DGU dataset for the 10-year period 2012–2021.

Study population

Children up to age 15 and adults aged 16 to 50 who underwent either conventional shock-room imaging or multi-slice WBCT were included in the study. The inclusion or exclusion criteria are listed in the Box. The methods are described in detail in the eMethods section.

Box

Inclusion and exclusion criteria for the study cohort

Stepwise analysis

In the first step of the analysis, the groups of patients who did and did not receive WBCT were compared in each of the two cohorts (children and adults).

In the second step, mortality data of patients with and without WBCT were analyzed in each of the two cohorts and compared with the expected mortality (prognosis). The quotient of expected and observed mortality, known as the standardized mortality ratio (SMR), was calculated. SMR is an established term in the TR-DGU; it is used as a quality parameter to compare treatment outcomes between cohorts of patients with different degrees of injury.

In the third step, a propensity score was derived from identified predictors for receiving a WBCT scan. With the aid of the propensity score, a matched-pairs analysis was carried out for children with and without WBCT.

The results are presented mainly as frequencies (N) and percentages. For mortality and SMR, 95% confidence intervals [95% CI] are also stated. The intent was for any differences that might be observed to be evaluated primarily with respect to their clinical relevance. The analysis was carried out with the statistics program SPSS (version 21, IBM Inc., Armonk, NY, USA).

Results

A total of 65 092 records were included, of which 4 573 (7%) were from children and 60 519 (93%) from adults.

Comparison of children and adults

Most of the injured children (62%) were male, as were most of the injured adults (77%), but the percentage of the injured who were female was higher among children to a statistically significant extent (38% vs. 23%, p < 0.001).

Comparisons of the mechanisms of injury and bodily sites of injury in children versus adults are displayed in Figures 1 and 2, respectively. Overall, injuries were slightly less severe in children than in adults (mean Injury Severity Scores [ISS]: 19.3 (± 11.3) and 21.1 (± 11.6), respectively.

Figure 1

Comparison of the most common mechanisms of injury in children and adults

Figure 2

Comparison of the distribution of clinically relevant injuries in children and adults

As seen in Table 1, WBCT was more common in older children and in children in higher-level trauma centers (local < regional < supraregional). WBCT was equally common in boys and girls (65.9% versus 65.0%). Overall, 65.5% of children under 16 years of age received WBCT; the rate of WBCT was lowest in the youngest age group (56% for children up to and including age 5).

WBCT versus stepwise diagnosis

In the non-risk-adjusted comparison of mortality in the overall cohorts of children with and without WBCT (Table 2), children who underwent WBCT had a higher mortality (p < 0.001) but also had a significantly worse prognosis (expected mortality) according to the Revised Injury Severity Classification Version II (RISC II). No difference in mortality was seen between children with and without WCBT in the risk-adjusted SMR comparison (SMR 0.97 and 0.95, respectively; p = 0.90). Among adults, however, the risk-adjusted comparison did reveal a lower SMR in the WBCT group (p = 0.028).

Table 1

Total number of patients and frequency of WBCT according to age and level of trauma center care

Table 2

Observed and expected mortality of children and adults with and without WBCT

Propensity-score analysis

A propensity score for the probability of receiving WBCT was derived for all of the injured children. The following predictors were identified:

• higher level of care of the trauma center (local < regional < national)
• older child
• lower Glasgow Coma Score (GCS)
• higher Injury Severity Score (ISS)
• significant thoracic trauma (Abbreviated Injury Scale [AIS] ≥ 3)
• injury of multiple body regions
• Isolated traumatic brain injury (TBI) was a negative predictor of WBCT.

1101 pairs of children were matched on the basis of their propensity scores. The two groups were similar in many respects, as seen in Table 3. Their in-hospital mortality was the same (44 versus 43 deaths). However, x-rays were significantly more common in the group without WBCT (41% versus 23%); moreover, 42 children in this group underwent magnetic resonance imaging (MRI) (4%). Significantly more patients in the WBCT group than in the non-WBCT group had been injured in a traffic accident (58% vs. 49%, p < 0.001).

Table 3

Characteristics of children in matched pairs with similar propensity scores; in each pair, one child received a WBCT and the other did not

Discussion

The appropriate diagnostic evaluation of severely injured children is a controversial matter. WBCT is increasingly favored despite the absence to date of a clearly demonstrated clinical advantage (2, 17, 18, 19). Proponents of WBCT cite the insufficient specificity and low sensitivity of sonography and conventional diagnostic methods; on the other hand, many pediatric surgeons, pediatricians, and pediatric intensivists report positive clinical experience without WBCT, and the anatomic conditions for sonography are known to be better in children (20, 21, 22). Independently of this discussion, conventional diagnostic methods may suffer from weaknesses that WBCT is not expected to have. Against this theoretical background, the increasing implementation of WBCT in severely injured children seems reasonable on its face.

The most important negative aspect of WBCT in the diagnostic evaluation of trauma diagnostics is the high radiation dose to the patient. No robust, multicenter dose evaluations are yet available for either adults or children, but the dose reference values (DRV) of the German Federal Office for Radiation Protection (BfS), which were established on the basis of a large number of elective CT examinations, can be used as a rough guide (23, 24). The sum of the DRVs for CT examinations of the skull, chest, and abdomen/pelvis can serve as a realistic order-of-magnitude estimate of the the radiation exposure to be expected for CT from the vertex to the ischium. For this purpose, age-adjusted effective doses (E) were calculated from the DRV of the three body regions and the corresponding k-factors, and these were summed to yield an E-WBCT (23, 24, 25). For the group of children aged up to 1 year, no E-WBCT can be calculated, as there is no existing DRV for the abdomen and pelvis. For the other age groups, values between 11.9 and 16.6 mSv were obtained. In relation to the average natural radiation exposure of 2.1 mSv/a in Germany, this corresponds to an „aging“ of between 5.6 and 7.9 years in just a few minutes while the young patient undergoes WBCT.

A recent paper documented a mean E of 4.8 mSv for a dose-optimized low-dose pediatric WBCT protocol, which is a very good result (26). The BfS considers children to need special protection because they are more sensitive to radiation than adults and the repair mechanisms for DNA injury function less well in children, leading to an increased risk of radiation-induced leukemia and solid malignant tumors (27). It follows that CT in childhood is justified only if it yields a clearly demonstrable clinical advantage. In the study described in this paper, we found such an advantage for adults, but not for children. Meanwhile, a number of papers (11, 12, 13, 16, 28) have documented the following:

• WBCT is performed more often than necessary, e.g., in children without any relevant injuries
• decisions regarding whether or not to operate are more likely to be based on the patient’s clinical condition than on the radiologic findings
• no survival benefit from WBCT is demonstrable.

Against this background and in view of the results of this study, the recommendations found in the current German guideline deserve a critical re-examination (2, 14). In contrast, the British NICE guideline entitled “Major Trauma” contains a recommendation against the routine use of WBCT in persons under 16 years of age (29, 30).

It is noteworthy that the prognosis (expected mortality) of the children who received WBCT was worse, so that a direct comparison of actual mortality between cohorts was of limited informative value. We therefore carried out a risk-adjusted comparison of SMR. In the RISC II prognosis score used for adjustment, the prognoisis is calculated on the basis of 13 parameters including the severity and type of injury, age, sex, pupils, Glasgow Coma Scale, blood pressure, coagulation (prothrombin time and partial prothrombin time), base deficit, hemoglobin level, previous illness, and circulatory arrest (31, 32).

The TR-DGU was established in order to improve the care of adult polytrauma patients. This explains why some of its parameters are based on normal values for adults. For example, a systolic blood pressure of ≤ 90 mm Hg is defined as shock in many papers from the TR-DGU, yet this value may be normal in children. This one example highlights the limitations of the adult database, which compels critical evaluation of the markers collected in the registry.

The results of our study conflict with the recommendations found in the current literature, including the German guideline, according to which WBCT is the standard diagnostic technique to be used in the evaluation of the multiply traumatized child (17, 33, 34). In children, in view of the need for rapid action, clinical experience, and the undoubted positive attributes of WBCT as a diagnostic method, WBCT may be justified and reasonable in the following situations:

• if the clinical impression of the child on arrival in the shock room is that of a severely injured patient;
• if the known mechanism of injury clearly puts the child at high risk;
• if the child had to be intubated by the initial medical responders because of a low GCS at the scene of the injury;
• or if the child has already been found to have severe injuries to multiple body regions or body cavities.

For all other children, given the current data, a conventional, staged diagnostic evaluation with sonography, x-ray and, if necessary, organ-based CT examinations (for example, cranial CT [cCT]) are presumably equally effective, with less exposure to radiation. The care of the injured child should then be based on the following, rather than on WBCT:

• thorough clinical examination by physicians from the fields of pediatric surgery, traumatology, and/or pediatrics and pediatric intensive care medicine who are experienced in the treatment of severely injured children;
• a selective, step-by-step diagnostic evaluation;
• and re-evaluation of the findings at short intervals.

The key question that arises on the basis of the present work and further articles (11, 12, 13) is why no definitive advantage for WBCT has yet been demonstrable in children. Unfortunately, there is no conclusive answer, but certain points deserve to be briefly mentioned. Children are injured by different mechanisms than adults, and pediatric trauma is more likely to involve head injury, including isolated TBI (Figures 1 and 2). In such cases, selective cranial CT often suffices as a diagnostic tool, and WBCT is not likely to yield any further advantage. Moreover, children are less likely to have severe chest and limb (including pelvic) injuries, which are the types of injury for which rapid WBCT would be expected to have the greatest benefit. Further studies are needed to confirm or refute these hypotheses.

Limitations

This study is not a randomized clinical trial, but rather an analysis of registry data, with the corresponding limitations. The data do not permit any conclusions about structural or infrastructural differences among the participating hospitals. It is also unclear whether physicians from the fields of pediatrics, pediatric surgery, and/or pediatric intensive care were generally involved in the care of the injured children, perhaps even from the shock room onward. Only conjectures can be offered to explain the difference in SMR between the cohorts. A further limitation of this work is that the RISC II score that was used to determine prognosis was originally developed for adult trauma patients, not for children. Of the 5 scoring systems for traumatized children that are found in the literature (35, 36, 37, 38, 39), the most recent is the Pediatric Trauma BIG Score, validated in the TR-DGU, which has the best predictive value of all (40). Yet none of the pediatric trauma scores so many variables into account in such a complex way as the RISC II, and this, in our view, justifies its use.

Conclusion

This study did not show any survival benefit for WBCT in the diagnostic evaluation of trauma in children. Children who have a low Glasgow Coma Score (≤ 8) at the scene of the trauma, wo appear to be severely injured on arrival in the shock room (MAIS ≥ 3), or who have multiple injuries in multiple body regions may stand to benefit from primary WBCT. In general, because of the higher radiation exposure, the indication for WBCT should be critically discussed within the team, and its benefits and risks carefully weighed. The findings of this study should be considered in the future development of relevant guidelines.

It would be desirable to foster the development of a pediatric trauma registry analogous to the TR-DGU with adapted parameters, or else to extend the TR-DGU with appropriate modules to facilitate study of the causes of the differences documented here and to enable the creation of appropriate practical recommendations.

Acknowledgement

The authors thank all the hospitals that participated in the TR-DGU, which are listed on the TR-DGU website (www.traumaregister-dgu.de).

Conflict of interest statement

R. L. received study support (third-party funding) from the Academy of Trauma Surgery (Akademie der Unfallchirurgie, AUC GmbH), the owner of the DGU Trauma Registry

S. R. is a member of the German Roentgen Society (Deutsche Röntgengesellschaft e.V.) and the German Society for Trauma Surgery (Deutsche Gesellschaft für Unfallchirurgie). He is also a board member of the Radiological Society of Saxony (Sächsische Radiologische Gesellschaft e.V.).

P. H-C. is a member of the German Society of Anesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin, DGAI), the Association of Emergency Physicians in Saxony-Anhalt (Arbeitsgemeinschaft der in Sachsen-Anhalt tätigen Notärzte, AGSAN), and the Endovascular Resuscitation and Trauma Management (EVTM) Society.

Manuscript received on 31 May 2022, revised version accepted on 29 December 2022.

Translated from the original German by Ethan Taub, M.D.

Corresponding author
PD Dr. med. habil. Peter Hilbert-Carius
Klinik für Anästhesiologie, Intensiv-, Notfallmedizin und Schmerztherapie
Bergmannstrost BG-Klinikum Halle (Saale)
Merseburger Str. 165
D-06112 Halle (Saale), germany

Cite this as:
Berger M, Lefering R, Bauer M, Hofmann GO, Reske S, Hilbert-Carius P, on behalf of the DGU Trauma Registry: Mortality with and without whole-body CT in severely injured children. Dtsch Arztebl Int 2023; 120: 180–5. DOI: 10.3238/arztebl.m2022.0414

►Supplementary material

eReferences, eMethods:
www.aerzteblatt-international.de/m2023.0414

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