Research involving traumatic arrests is rare. This study examined outcomes of patients with traumatic arrests treated in US trauma centers and identified factors associated with survival in this population using the largest trauma database in the US.
The overall survival to hospital discharge among patients with traumatic arrests was 11.1%. This rate is slightly lower than the rate of 12.5% reported by Ahmed et al5 but higher than other survival rates reported in earlier studies.13,16 Young, white and male individuals continue to be mostly affected by traumatic arrests.1,5,11 Improved survival in traumatic arrests presenting to U.S hospitals has been previously attributed to the increasing frequency of emergency interventions such as ED thoracotomy and other procedures.17 Variation in survival rates of patients with traumatic arrest is however mostly related to differences in study sample selections with most studies including in the denominator arrests that are not transported to hospitals.18 Our study included only patients who were transported to a trauma center which might have overestimated the survival rate since patients declared dead on scene are not usually included in the NTDB registry.
There were several factors associated with increased survival in patients with traumatic arrests. Demographic factors positively associated with survival included age group (16-64) (compared to age ≥ 65) and female gender. This differs from previous studies5, 16, 19 where no similar associations were reported. Patients in the younger age are usually expected to have better odds of survival because of lower comorbidities. Female gender was significantly associated with survival in this population. A previous study did not identify significant association between female gender and outcomes in severely injured patients.20 Age stratification was however done in that study to account for hormonal status. The finding in our study need further examination with the potential role of other unmeasured confounders such as role of hormones based on age category (pre vs post-menopausal) and obesity etc.
Several injuries related characteristics were also significantly associated with survival. Type of trauma (blunt vs penetrating), which is mainly used for categorization in trauma study, was not significantly associated with survival similar to other studies.5, 16, 21 Other previous studies however reported better outcomes with penetrating22 or with blunt injuries.23 These contradictory findings constitute a challenge for guidelines about withholding resuscitation in traumatic arrests:16 Several case reports24, 25 discuss exceptions to guidelines with unexpected return of spontaneous circulation in patients with arrests from blunt or penetrating injury.16 Prehospital guidelines for withholding resuscitation in the field should therefore be carefully examined to avoid potential prehospital management errors in challenging cases such as cardiac arrest after trauma.8 EMS providers frequently face challenges in detecting a pulse in patients with traumatic arrest25 which could significantly impact survival of these patients if prehospital resuscitation is withheld.
The mechanisms of injuries were positively associated with survival when compared to firearm mechanism. Previous studies examining only blunt injury mechanisms showed survival benefit for patients with fall-related injuries when compared to MVT.22,26 This study examined traumatic arrests from different injury mechanisms and demonstrated poorer outcomes with firearm related injuries. In fact, case fatality rate of firearm has been previously shown to be much higher than any other mechanism of injury.27, 28 This high firearm lethality is related to several factors including number of entrance wounds, range and site of entrance wounds and intentionality.20, 29 The study findings highlight the need for better understanding of firearm related injuries and for developing preventive measures targeted to improve survival in this population.
Injury body region was found to be significantly associated with survival: Injuries to vital locations such as head and neck, or torso were associated with poor outcomes. This was expected because of the risk of bleeding and hemorrhagic shock from damage to vital organs30 and is in line with the ATLS approach to management of trauma patients by prioritizing management according to life-threatening injuries.31 Other factors were also found to be positively associated with survival such as specific types of injuries (fractures, internal organ damage) in addition to alcohol or drug use. These are more likely related to reporting of such data elements in patients who survive after the initial resuscitation measures. Such patients are expected to have a more detailed documentation of minor injuries or better description of other elements contributing to the injury event.
As expected an injury severity score (ISS<16) was associated with higher survival in traumatic arrest patients. This finding is in line with previous studies 5, 13, 16, 25 and validates the need to incorporate ISS in outcome predictive models in not only trauma patients but also in traumatic arrests to avoid futility of extreme measures in resuscitation.
Our study also identified that hospital location in the South was associated with increased survival (reference Northeast) for patients with traumatic arrests. While improved outcomes in trauma patients have been previously linked to geographic clustering of trauma centers which are primarily located in the Northern area32 and where patients benefit from the greatest access to trauma Level I and II centers within 45 and 60 minutes,33 our study did not identify such association. In our study sample, more hospitals were located in the South (47.2%) than in the Northeast (13.9%). Patients in the South were more likely to survive as compared to those in the Northeast (17.1% vs. 13.4%) and additional stratification by mortality status revealed that disproportionate distribution of the participant hospitals may be responsible for this apparent survival differences between the two regions (Only two patients with firearm injury survived to hospital discharge in the Northeast as compared to 41 patients in the South). Further research should examine closely the impact of hospital region on survival in trauma patients.
Financial coverage status was also significantly associated with survival. When compared to self-payment or uninsured, all other methods of coverage were positively associated with survival. The available literature reports contradicting findings on financial coverage and association with survival in trauma patients. Greene et al. concluded that insurance status was a predictor of outcome with uninsured patients being at higher risk of death in both blunt and penetrating trauma34 while Lober et al. noted a better survival in patients with no insurance coverage19 attributing this finding to potentially larger proportion of healthy patients in the uninsured group. In this study of traumatic arrests any insurance status (compared to uninsured) was associated with improved outcomes. Further research is needed to clarify the reasons for this disparity such as examining resources utilization including but not limited to access to surgical procedures.
This study has potential limitations related to its retrospective nature and to availability of data reported in the database. The NTDB uses ICD-9 coding for the data retrieved from different hospitals and is like other national databases subject to coding variations and errors. This study did not include traumatic arrests that were not transported to a trauma center which might have led to overestimation of the survival rate in this group of patients. The NTDB also uses “convenience samples” from disproportionate number of large to small hospitals that contribute to the database. This unequal sample size across regions and the lack of weighting should be taken into considerations when comparing outcomes across different US regions.
Despite these limitations, the NTDB is the largest database for trauma in the United States of America collecting data from over 900 hospitals and the study findings can be generalized to hospitals in the US and to other settings with similar trauma systems. .