In the present study, the undertriage proportion was more than twice as high as the ACSCOT’s recommended < 5%16, which is similar to that reported in other European and American studies 17–19. Several authors have reported even higher rates of undertriage. Indeed, in a similar EMS system (physician-led), Bouzat et al. reported that 18% of included patients were undertriaged 7. In paramedic-led prehospital systems, undertriage was also higher: Voskens et al. (Neverthelands) reported a 21.6% proportion of undertriage 17, Schellenberg et al. (USA) 16% 18 and Xiang et al. (USA) 34% 19. Therefore, our physician-led prehospital system showed similar or better triage performance compared to other paramedic-led systems. However, since the definition of undertriage is heterogeneous in the literature, estimating and comparing the true undertriage rates between studies is difficult. Indeed, in 2019, a systematic review reported four definitions of undertriage: based on ISS, formula for mis-triage, need for life-saving emergency intervention, and patients triaged to a non-trauma centre 6 .
Herein, all patients older than 30 years of age were at greater risk of undertriage, and this was particularly significant for those aged 51 to 65 years. We cannot exclude insufficient statistical power to explain why age above 65 was not significantly associated with undertriage. Nakahara et al. reported a similar result; a trend towards a greater risk of undertriage for older patients, significant for the 45–54 year age group20, and most studies also reported that age was a predictive factor of undertriage: ≥ 55 years19, ≥ 65 years 1, 2, ≥ 80 years21. This is a particularly important issue as improved outcomes for older adults admitted in centers with higher levels of trauma care designation have been reported 22, 23. A specific triage protocol to identify high-risk geriatric injured patients could further be explored, as it was found to lead to significant lower mortality 24. Interestingly, we found that patients who sustained gunshot/stab wounds had a lower risk for undertriage compared to those involved in a road collision. This is in line with Schellenberg et al.’s results which reported a higher risk for undertriage following a blunt trauma, especially in motor vehicle collisions18. Although it is not entirely clear why, it may be explained by the fact that the injury severity of a penetrating trauma may be more obvious for prehospital caregivers (i.e., external haemorrhage, limb amputation) compared to blunt trauma. Furthermore, European physicians are less exposed to penetrating trauma compared to the numbers reported in US studies 25–27.
An original finding of this study is that patients who had a prehospital FAST were at lower risk of undertriage regardless of the severity of their injuries. Ultrasound-based clinical algorithms might improve the assessment of injured patient, but their effectiveness in the prehospital setting lacks evidence 28. We assume that fluid detection influenced physicians to consider patients as requiring a higher level of care; another hypothesis is, however, that physicians performing FAST had more experience and better assessment capacities. The value of FAST in our field triage algorithm needs to be further and specifically explored.
Another interesting finding is that fewer patients transported by helicopter were undertriaged. This might be explained by higher availability of helicopter emergency medical services (HEMS) in level-I centres. Nevertheless, there was no significant association between the type of transport and in-hospital mortality, which is in accordance with that reported elsewhere 29, 30. We also found that prehospital on-scene management ≥ 60 minutes was associated with lower undertriage compared to faster management (0–30 minutes), regardless of patients’ severity (ISS) and prehospital ALS performed. Nevertheless, there was a very small difference in on-scene times between under- and correct-triage groups, which is of limited clinical significance. Hence, those results cannot support systematic longer on-scene time.
In the present study, there was no significant association between undertriage and in-hospital mortality, compared to that reported elsewhere 1, 2, 31. This may partly be due to the relatively small sample size. Of note, a large proportion of undertriaged patients were admitted to level-II centres that offer a wide range of 24-hour in-house resources (intensive care, general and orthopaedic surgeons, emergency physicians, embolisation, CT scan). Hence, a patient not requiring neuro- or cardiothoracic surgery could be properly managed in a level-II centre.
The study does, however, have some limitations. Its retrospective design means that it is not immune to data collection mistakes. The exact locations of the on-scene traumas were not available in the database, and we could not therefore evaluate the distance to the nearest trauma centre, which may have played a significant role in the choice of destination. Furthermore, triage may have been influenced by other elements that were not collected (i.e., chronic conditions, trauma centre overcrowding, a decision of withdrawing treatments, futility or family/patient wishes). Even if our definition of undertriage is validated by the ACSCOT5, it may also be argued whether ISS is the most accurate tool for assessing whether a patient required level-1 trauma care compared to a clinical definition based on the need for critical intervention (i.e., urgent surgery, massive blood transfusion, craniectomy, or secondary transfer). .
Further research is needed in our regional physician-led prehospital system to improve the triage of major trauma patients. More specifically, the integration of systematic FAST on-scene should be evaluated in such EMS system. Refining undertriage definition should also be considered in similar EMS systems to fit local trauma system organization.