Comparing Emergency Department Gunshot Wound Data with Mass Casualty Shooting Reports
Authors: Walsh Andrew 
Published: May 2017

ObjectiveTo determine whether mass casualty shooting events are capturedvia syndromic surveillance data.IntroductionShootings with multiple victims are a concern for public safetyand public health. The precise impact of such events and the trendsassociated with them is dependent on which events are counted. Somereports only consider events with multiple deaths, typically four ormore, while other reports also include events with multiple victimsand at least one death.1Underreporting is also a concern. Somecommonly cited databases for these events are based on media reportsof shootings which may or may not capture the complete set of eventsthat meet whatever criteria are being considered.Many gunshot wounds are treated in the emergency departmentsetting. Emergency department registrations routinely collected forsyndromic surveillance will capture all of those visits. Analysis ofthat data may be useful as a supplement to mass shooting databases byidentifying unreported events. In addition, clusters of gunshot woundincidents which are not the result of a single shooting event but stillrepresent significant public safety and public health concerns mayalso be identified.MethodsEmergency department registration data was collected fromhospitals via the EpiCenter syndromic surveillance system. Gunshot-related visits were identified based on chief complaint contentsusing EpiCenter’s regular expression-based classification system.The gunshot wound classifier attempts to exclude patients with pre-existing wounds and shooting incidents involving weapon classes thatare lesser concerns for public safety, such as nail guns and toy guns.Gunshot-related visits were clustered by day of registration andseparately by facility, by patient home zip code, and by patienthome county. The largest clusters of each type were compared viamanual search against media reports of shootings and against the GunViolence Archive mass shooting database.ResultsA total of 23,132 gunshot-related visits were identified from 635healthcare facilities from 2013 to 2015. From these, the five largestclusters by facility, by zip code, and by county were identified. Theclusters included 112 gunshot wounds in total, ranging in size from4 to 12 with a median of 7.Of the 5 facility clusters, 5 had a corresponding media story and 2were located in the shooting database. Of the 5 zip code clusters, 1 hada corresponding media story and none were located in the shootingdatabase. Of the 5 county clusters, 4 had a corresponding media storyand 1 was located in the shooting database.ConclusionsMultiple gunshot wound patients being treated on the same daywere not necessarily all shot during the same incident or by the sameshooter. The information available in a syndromic surveillance feeddoes not allow for direct identification of the shooter or shooters.Given that limitation, a complete correspondence between clustersidentified in syndromic surveillance data and mass shootings was notexpected. The strong correlation between clusters and media coverageindicates that the news is a reasonable source for shooting data. Thesmaller overlap with the mass shooting database is likely due to themore stringent criteria required for an incident to qualify as a massshooting.It is still notable that the majority of gunshot clusters were notassociated with any particular mass shooting incident. This serves asa reminder that mass shootings represent only a small portion of thetotal gun violence in the United States. Healthcare data representsa significant additional data source for understanding the completeimpact of gun violence on public health and safety.Weekly time series of gunshot-related emergency department visits