Clustered Arrivals of Firearm-Injured Patients in an Urban Trauma System: A Silent Epidemic

Background: Recent attention has been paid to the role trauma centers play in responding to mass shootings. Although high-profile public events are the primary focus of media and policy makers, firearm-injured patients (FIPs) present in clusters to urban trauma centers every day. We examined the burden of FIP clusters from an urban trauma system perspective.

Study design: In this descriptive epidemiologic study, we used data from the Philadelphia Police Department registry of shootings from 2005 to 2015. Variables included patient demographics, injury date and time, receiving hospital, and mortality. We defined clustered FIPs as those arriving within 15 minutes of another FIP. We used rolling temporal windows to calculate the number of FIP clusters for each hospital, assessed patient demographic characteristics and mortality, and used linear regression models to evaluate trends in FIP cluster rates.

Results: Of the 14,217 FIPs included, 22.1% were clustered. There were 54 events when 4 or more FIPs presented within 15 minutes and 92 events when 4 or more FIPs presented within 60 minutes. Clusters of FIP occurred most frequently during night shifts (7:00 pm to 7:00 am) (73.1%) at level I trauma centers (93.6%), with geographic clustering demonstrated at the hospital level. Compared with the overall FIP population, clustered FIPs were more likely to be female (p = 0.039), injured at night (p = 0.031), but less likely to die (p = 0.014). The rate of FIP clusters and mortality remained steady over the course of the study.

Conclusions: In the trauma system studied, FIP clusters are common and are likely to occur at similar rates in other urban centers. Therefore, the immediate burden on health care resources caused by multiple FIPs presenting within a short period of time is not limited to traditionally defined mass shootings.