Among all high-income nations, the United States still leads in firearm-related injury mortality.15,16 Blunt trauma, however, is the predominant mechanism of traumatic injury in the US. Several epidemiological studies have examined the incidence and mortality rates of penetrating trauma in various geographies.15–19 In general, the rate of penetrating injuries was estimated to be less than 10% of all adult traumas. A discrepancy exists in the distribution and severity of penetrating injuries among Level I/II trauma centers (Fig. 1). Previous studies have demonstrated an inverse relationship between socioeconomic status and traumatic injury.20,21 In the United States, the number of penetrating injury patients treated in a single institution ranges from 2.6 to 890.6 per year (Fig. 1). Twenty trauma centers treat more than 400 penetrating injury patients per year.
There is evidence of a volume-outcome relationship where higher surgical volume results in lower postoperative mortality.1–3 In our study, the total number of all trauma patients does not improve the survival of penetrating trauma patients (p = 0.452, Table 3). The volume effect is more complex and specific to injury subtype treated. Figure 2 shows a positive relationship between survival rates of penetrating injury patients in institutions and the numbers of penetrating injury patients treated in a specific institution. This effect was especially significant in patients with more severe injuries (ISS ≥ 16 or ISS ≥ 25) (Figs. 2B and C).
In the current study, we used 167 penetrating injury patients per year as the high cutoff value (top 25%) and 36.6 penetrating injury patients per year as the low cutoff value (bottom 25%) to evaluate survival in trauma centers (Fig. 1B). A comparison between the institutions with high and low volume of penetrating injury patients (167 vs. 36.6 patients per year) showed that high-volume institutions (>167 penetrating injury patients per year) showed a distinct survival advantage with a higher grade of injury (ISS ≥ 25). For all ISS, number of penetrating patients does not affect survival either for all centers grouped together or the top and bottom quartiles (Fig. 2A and Table 2). However, these high-volume centers (for all ISS) were associated with survival rates for penetrating trauma equivalent to low-volume centers, which treated less severe and less ill patients (survival rate, 96.0% vs. 96.3%, p = 0.230). For ISS ≥ 16 (which includes patients with ISS ≥25) survival is better for all centers but not for the top versus the bottom quartiles (Fig. 2B and Table 2). For ISS of 25 or higher, survival is better not only for all centers but also for the top and bottom quartiles (Fig. 2C and Table 2). This suggests that the difference in survival among the centers is driven primarily by the survival of more severely injured patients (survival rate for ISS ≥ 25: 71.7% vs. 66.8%, p < 0.001) (Table 2).
While it is hard to make generalizations, one would assume that penetrating injury to head can lead to a higher mortality and that penetrating extremity injury is more salvageable than penetrating injury to the torso. Another assumption might be that GSWs are more lethal than stab wounds. Our data found that the higher-volume centers treat more penetrating injuries to the head, torso and extremities and more GSWs in general than low volume centers (52.5% vs. 38.9%, p < 0.001). The AIS scores of the head, and not torso or extremities, were significantly higher in the high-volume centers.
Gunshot wounds usually occur in populations with lower socioeconomic status, and most violence occurs in neighborhoods with concentrated poverty and housing.22–25 In addition to increased law enforcement efforts against gun violence, equal attention should be paid to improving medical survival from GSWs. Delayed surgical intervention for significant injuries, such as torso penetrating injuries, can increase trauma-related morbidity and mortality rates.26,27 Therefore, a trauma center that provides rapid transportation and timely treatment is necessary for people who are victims of GSWs. Furthermore, while the trauma centers analyzed have very similar expert personnel, in a high-volume penetrating center the personnel are exposed to more penetrating trauma. The results of the current study suggest that increased penetrating volume is associated with better survival.
Improved outcomes of trauma patients who were treated at trauma centers have been previously reported. However, volume effect has not been evaluated based on mechanism of injury. The management of a non-penetrating injury can be as complicated as the management of penetrating injury.28,29 Therefore, volume-related improved outcomes may exist not only for penetrating injury patients. We evaluated whether the salutary patient volume effect is specific to penetrating injuries. A risk adjustment model using linear regression analysis was created to evaluate independent risk factors that were related to the survival rate of penetrating trauma patients. Older age, using ventilator, and higher ISS show significantly negative effects on the survival of penetrating trauma patients. Trauma centers show improved survival rates of penetrating trauma patients associated with increased number of penetrating injury patients treated per year (p = 0.032). Although it is difficult for emergency medical service personnel to evaluate injury severity at the scene, penetrating injury patients is more easily identified. Triage of the right severity penetrating injury to the correct regional trauma center is more complex. The a priori assessment of a higher ISS injury and triage to a “high-volume penetrating trauma center” would need a discussion, evaluation, and consensus within each region.
A nationwide data bank with a large sample size was evaluated in the current study, but the conclusions are limited due to the retrospective nature of the data and some missing elements in the NTDB. In addition, the functional outcome of penetrating injury patients and the cost-effectiveness of subspecialized trauma centers were not evaluated. We were not able to evaluate if concentrating penetrating trauma in a few centers would actually improve overall survival in a local trauma system. This would depend on the location of penetrating hotbeds and the deleterious effect of further decreasing penetrating trauma patients going to already low penetrating trauma centers. Further studies with a prospective design and long-term follow-up are needed.
The authors have no commercial associations or sources of support from any grant, funding source or commercial interest including pharmaceutical or device companies that might pose a conflict of interest.
1. Jonker FHW, Hagemans JAW, Verhoef C, Burger JWA. The impact of hospital volume on perioperative outcomes of rectal cancer. Eur J Surg Oncol
2. de Wilde RF, Besselink MG, van der Tweel I, de Hingh IH, van Eijck CH, Dejong CH, Porte RJ, Gouma DJ, Busch OR, Molenaar IQ. Dutch pancreatic cancer group. Impact of nationwide centralization of pancreaticoduodenectomy on hospital mortality. Br J Surg
3. Kopp W, van Meel M, Putter H, Samuel U, Arbogast H, Schareck W, Ringers J, Braat A. Center volume is associated with outcome after pancreas transplantation within the Eurotransplant region. Transplantation
4. Hoff WS, Schwab CW. Trauma system development in North America. Clin Orthop
5. Champion HR, Copes RH, Sacco WJ, Lawnick MM, Keast SL, Bain LW Jr., Flanagan ME, Frey CF. The major trauma outcome study: establishing national norms for trauma care. J Trauma
6. Mullins RJ, Mann NC. Population-based research assessing the effectiveness of trauma systems. J Trauma
7. Bazzoli GJ, Madura KJ, Cooper GF, MacKenzie EJ, Maier RV. Progress in the development of trauma systems in the United States. Results of a national survey. JAMA
8. MacKenzie EJ, Rivara FP, Jurkovich GJ, Nathens AB, Frey KP, Egleston BL, Salkever DS, Scharfstein DO. A national evaluation of the effect of trauma-center care on mortality. N Engl J Med
12. R Core Team. R: A language and environment for statistical computing
. Vienna, Austria: R Foundation for Statistical Computing; 2014. URL http://www.R-project.org/
Accessed January 15, 2019.
13. Haider AH, Hashmi ZG, Zafar SN, et al. Developing best practices to study trauma outcomes in large databases: an evidence-based approach to determine the best mortality risk adjustment model. J Trauma Acute Care Surg
14. Kutner MH, Nachtsheim CJ, Neter J. Applied Linear Regression Models
. 4th ed. New York, NY: McGraw-Hill Irwin; 2004.
15. Richardson EG, Homicide Hemenway D. Homicide, suicide, and unintentional firearm fatality: comparing the United States with other high-income countries, 2003. J Trauma
16. Lee J, Quraishi SA, Bhatnagar S, Zafonte RD, Masiakos PT. The economic cost of firearm-related injuries in the United States from 2006 to 2010. Surgery
17. Whittaker G, Norton J, Densley J, Bew D. Epidemiology of penetrating injuries in the United Kingdom: a systematic review. Int J Surg
18. Zebib L, Stoler J, Zakrison TL. Geo-demographics of gunshot wound injuries in Miami-Dade county, 2002–2012. BMC Public Health
19. Demetriades D, Velmahos GC. Penetrating injuries of the chest: indications for operation. Scand J Surg
20. Kacker S, Bishai D, Mballa GA, Monono ME, Schneider EB, Ngamby MK, Hyder AA, Juillard CJ. Socioeconomic correlates of trauma: an analysis of emergency ward patients in Yaoundé, Cameroon. Injury
21. Nantulya VM, Reich MR. Equity dimensions of road traffic injuries in low- and middle-income countries. Inj Control Saf Promot
22. Livingston DH, Lavery RF, Lopreiato MC, Lavery DF, Passannante MR. Unrelenting violence: an analysis of 6,322 gunshot wound patients at a level I trauma center
. J Trauma Acute Care Surg
23. Kyriacou DN, Hutson HR, Anglin D, Peek-Asa C, Kraus JF. The relationship between socioeconomic factors and gang violence in the City of Los Angeles. J Trauma
24. Sampson RJ, Rauenbush SW, Earls F. Neighborhoods and violent crime: a multilevel study of collective efficacy. Science
25. Nance ML, Carr BG, Kallan MJ, Branas CC, Wiebe DJ. Variation in pediatric and adolescent firearm mortality rates in rural and urban US counties. Pediatrics
26. Anderson IA, Woodford M, de Dombal FT, Irving M. Retrospective study of 1000 deaths from injury in England and Wales. BMJ
27. Kreis DJ Jr., Plasencia G, Augenstein D, Davis JH, Echenique M, Vopal J, Byers P, Gomez G. Preventable trauma deaths: Dade County, Florida. J Trauma
28. Blank-Reid C. A historical review of penetrating abdominal trauma. Crit Care Nurs Clin North Am
29. Isenhour JL, Marx J. Advances in abdominal trauma. Emerg Med Clin North Am