Median transfer times for patients undergoing pretransfer head CT alone and multiple CT were 287 and 298 minutes, respectively. Both of these times were significantly longer than the median transfer time (260 minutes) for patients who received no pretransfer CT (p < 0.0001, Wilcoxon rank-sum test). On multivariable regression modeling to adjust for age, sex, Injury Severity Score, injury mechanism, GCS score, and transfer region, the pretransfer CT category remained a significant predictor of longer transfer times (F = 35.4, p < 0.0001).
Table 3 provides details for neurosurgical intervention among the 964 patients who had a pretransfer head CT and a recorded pretransfer GCS. Overall, 35 (3.6%) patients required neurosurgical intervention, 17 (1.8%) emergently within 6 hours of presentation to our center. Patients with normal pretransfer GCS were significantly less likely to require any (3.1% vs. 6.9%, p = 0.04) or emergent (1.3% vs. 4.6%, p = 0.02) intervention. The most common indication for intervention was epidural hematoma.
Prevalence rates of pretransfer CT for each nontrauma center with at least 50 transfers during the study period, grouped by transfer region, are shown in Figure 1. Rates of pretransfer CT increased with increasingly distant regions from the PTC, with median rates of 27%, 37%, and 44% for in-county, adjacent county, and nonadjacent county transfers, respectively (p = 0.01, Wilcoxon rank-sum test). Within each of the three regions, centers differed significantly from each other in prevalence rates of pretransfer CT (p < 0.05, χ2 test). The results were nearly identical for prevalence rates of head CT alone.
This study of injured children transferred to a PTC from nontrauma centers provides useful information on the clinical impact and regional practice variability of pretransfer CT, particularly head CT alone.
First, we found that performance of pretransfer CT, whether of the head alone or of multiple anatomic areas, was associated with delays in transfer. CT head alone was associated with a median delay of approximately half an hour, whereas multiple CT was associated with a delay of nearly 10 additional minutes. These delays persisted after adjustment for transfer distance and other clinically relevant covariates.
Our findings are consistent with a previous study of 748 injured children transferred in to a level I PTC, which found higher probability of late transfer (>2 hours) among children receiving pretransfer CT, independent of injury characteristics and transport distance or mode.6 That study did not attempt to specifically quantify the CT-associated delay or evaluate the effect of head CT alone. In another study at a freestanding PTC in Utah, Fenton et al.3 demonstrated that any CT imaging prior to transfer was associated with prolongation of median transfer time by approximately 67 minutes. Those authors did not evaluate head CT alone or adjust for potential confounding variables, such as transport distance. Fahy et al.5 found the pediatric blunt trauma patients undergoing pretransfer chest or abdominal CT had a mean time from injury to PTC arrival that was 112 minutes longer than those who did not undergo CT. Adjustment for covariates and evaluation of head CT was not attempted.
Second, among patients who underwent pretransfer head CT, the overall likelihood of emergent neurosurgical intervention within 6 hours of PTC arrival was low (1.8%) and was strongly influenced by pretransfer GCS. Only 11 (1.3%) of 833 patients with normal pretransfer GCS required emergent intervention, and 3 (27%) of these underwent repeat imaging at the PTC prior to operation. This study was unable to evaluate the appropriateness of pretransfer CT according to validated clinical decision rules such as those developed by Kuppermann et al.10 However, the high proportion of patients with normal GCS receiving head CT alone, along with the low rate of emergent neurosurgical intervention, suggests that the practice of pretransfer head CT alone is overutilized in patients with normal GCS.
Patients with abnormal pretransfer GCS had a significantly higher rate (4.6%) of emergent neurosurgical intervention. Although head CT was indicated for these patients,10 whether the initial imaging was best performed before or after PTC transfer is unclear. Sixty-seven percent of the abnormal GCS patients who required emergent operation had imaging repeated at the PTC prior to intervention, and adult studies suggest that head CT prior to transfer does not expedite craniotomy.11 While the nearly half-hour delay associated with pretransfer head CT may seem like a small amount of time, minutes matter in trauma. Longer transfer times have been associated with a higher rate of complications, such as pneumonia, pulmonary embolism, sepsis, seizures, and postoperative hemorrhage, in pediatric trauma victims.12 Prolonged transfer time is also predictive of worse head injury outcomes in teenagers and adults.13 We saw higher injury severity and mortality among patients who received pretransfer CT, reflecting their higher acuity and potentially greater benefit of expeditious transfer.
Third, we found that the prevalence of pretransfer CT increased with increasing distance from the PTC, suggesting that referring clinicians are obtaining CT with the intention of using the information for planning longer-distance transports. However, we saw nearly two to four-fold variation in prevalence rates for pretransfer CT among centers within the same region (i.e., centers with similar transport distances). This high variability suggests that pretransfer CT practice patterns are largely driven by other factors specific to the referring institution. Interestingly, the referring institution with the lowest rate of pretransfer CT (15%) was a center in an adjacent county where pediatric emergency medicine (EM) care is formally coordinated with our PTC and pediatric surgeons provide emergency department consultation. To our knowledge, this center is the only nontrauma center in our catchment area that formally coordinates pediatric EM care with a regional PTC.
Our findings must be interpreted with several limitations in mind. This was a single-center study in a US state with a unique population distribution and regionalized pediatric trauma system, so it may not be generalizable to PTCs in other regional systems. The primary data source was a trauma registry, which may contain missing or inaccurate data. A large proportion of the transfer patient population had isolated long bone fractures, which would not be expected to routinely require CT scan. While we attempted to control for confounding variables between CT and non-CT groups with multivariable modeling, residual or unmeasured confounding could still affect the results.
In summary, CT prior to transfer from a nontrauma center to a PTC is associated with transfer delays, whether the head alone or multiple anatomic areas are imaged. The likelihood of emergent neurosurgical intervention is very low among patients with a normal pretransfer GCS, suggesting head CT is overutilized in transfer patients with normal mental status. The prevalence of pretransfer CT increases with distance from the PTC, but its high variability among centers of similar transport distance suggests that referring institution preferences play a large role in the decision whether or not to scan before transfer.
Decisions regarding pretransfer CT should be made in a collaborative fashion between referring institutions and the regional PTC. Ideally, shared protocols should be developed by pediatric trauma surgery, EM, and neurosurgery that provide consistent messaging to referring institutions regarding when to perform pretransfer CT. A united voice of collaboration and education may help reduce arbitrary variability and optimize the delicate balance of risk and benefit for injured children requiring transfer.
C.W.S., N.M.C. participated in the literature search. C.W.S., R.G., P.D.D., N.M.C.participated in the study design. C.W.S.participated in the data collection. C.W.S., R.G. participated in the data analysis. C.W.S., R.G., P.D.D., N.M.C. participated in the data interpretation. C.W.S., R.G., P.D.D., N.M.C. participated in the writing. C.W.S., R.G., P.D.D., N.M.C. participated in the critical revision.
The authors declare no conflicts of interest.
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Keywords:© 2019 Lippincott Williams & Wilkins, Inc.
Pediatric trauma; computed tomography; transfer; neurosurgery; practice variability