Effectiveness and Cost-Effectiveness of Emergency Department–Based Violence Intervention Programs in the United Kingdom: Protocol for a Quasi-Experimental Study

Background: Hospital-Based Violence Intervention Programs (HVIPs), based in Emergency Departments (EDs), have been proposed as a public health response to violence. These programs address the underlying reasons why patients are exposed to violence. In addressing any underlying modifiable risks and vulnerabilities HVIPs can reduce patients’ exposure to violence and therefore subsequent unplanned attendance into ED.Objective: The objectives of this study are to (1) assess whether patient involvement with a HVIP reduces the likelihood of unscheduled ED reattendance, (2) determine whether the presence of the HVIP improves ascertainment of violence in ED attendances, and (3) derive the costs of the HVIP and compare those to the benefits of the intervention and understand whether the HVIP represents value for money from a health service perspective. If an effect is observed, then models will estimate the health impacts, costs and potential savings over a longer time (eg, 10 years) period and for a national roll-out.Methods: ED patients are eligible for inclusion in the evaluation if they are normally resident in Wales, United Kingdom, aged 11 years and older. A controlled longitudinal natural experiment will be undertaken. The primary outcome is derived from the Emergency Department Dataset, routinely collected for all EDs in Wales, and is subsequent unplanned ED attendance. Case patients will be matched to control patients attending EDs without an HVIP. Analysis will derive the hazard rate for subsequent unplanned ED attendances using recurrent event analysis. The total monthly count of patients identified as attending because of violence in intervention EDs will be compared to the total count of Welsh control EDs in an interrupted time-series analysis to determine whether HVIPS increase violence ascertainment. To determine whether referral, versus no referral, to the HVIP represents value for money, we will undertake a cost-effectiveness analysis from the perspective of the National Health Service. The approval to access and analyze data housed in the Secure Anonymized Information Linkage (SAIL) databank, an ISO (International Organization for Standardization) 27001 certified and UK Statistics Authority accredited secure data environment, was granted by the SAIL independent Information Governance Review Panel (Ref: 1421). Findings will be presented at local, national, and international conferences and disseminated by peer-reviewed publication.Results: Design inputs arising from public patient involvement and engagement (PPIE) are reported. As a protocol, no further results are available.Conclusions: Novel methods are developed to provide the first robust evaluation of Emergency Department Violence Intervention Programs (EDVIPs).