Extremity trauma continues to remain a notable cause for presentation to the emergency department for trauma-level care, with penetrating extremity injuries comprising 5 to 15% of trauma cases. In the setting of vascular extremity injury, appropriate care protocols must be established to prevent life threatening complications including infection, non-union, limb salvage failure, and death. The two primary mechanisms of extremity trauma include penetrating trauma involving projectile and stab injuries, as well as blunt trauma involving fractures and joint dislocations. While central or peripheral vascular injuries constitute 1-2% of traumatic injuries, they result in more than 20% of trauma-related mortality demonstrating the importance of timely and efficacious care of extremity trauma patients, with particular emphasis on vascular injury assessment. The health care facility settings in which patients present have significant implications in the level of care provided, as availability of diagnostic and therapeutic resources may be limited in some settings. In such circumstances, patients may be transferred to alternate care facilities for higher level of care, with timing of transfer playing a substantial role in successful trauma patient care.

While it is noted that the treatment of severely injured patients in higher level trauma centers allows for access to increased care resources and improved prognostic outcomes, the patient outcomes of trauma patients transferred from lower level to higher level trauma centers may not be as clear. In an observational study assessing the influence of interhospital transfers of trauma patients on mortality, Waalwijk et al. demonstrated that transfer of severely injured, under-triaged patients to higher level trauma centers was associated with significantly reduced 24-hour and 30-day mortality rates. Similar findings were noted in the Garwe et al. retrospective cohort study, with results demonstrating a significantly lower 30-day mortality rate in patients who were transferred from non-tertiary to tertiary care centers, including Level 1 and Level 2 trauma centers, for treatment. With regards to interhospital patient transfers, there are established statewide trauma policies that guide "re-triage," which is defined as the urgent or emergent transfer of critically ill trauma patients from a non-trauma or lower level trauma facility to an upper level trauma center for higher level of care. The categories for re-triage consideration include perfusion, respiratory status, neurologic status, anatomic findings, and provider judgment. For example, anatomic findings that necessitate transfer to higher level of care facilities include extremity injury with neurovascular compromise. Important components of re-triage include early identification of patients who require higher levels of care as well as established transfer agreements between sending and receiving care facilities. Recognizing that patient transfers may impact overall health outcomes such that transferred extremity trauma patients may have worse clinical outcomes compared to non-transferred patients, we aim to investigate the relationship between transfer status and patient outcomes through conducting a retrospective observational case-control review of extremity trauma patients.