Bystander interventions and their impact on road injury outcomes: a scoping review

Background: Road injury remains a leading global cause of death and disability, particularly in low- and middle-income countries (LMICs) where emergency medical services (EMS) are often limited or incur prolonged response times. In many trauma cases, bystanders are the first to respond and may play a critical role in patient outcomes. While the importance of bystander cardiopulmonary resuscitation (CPR) in cardiac arrest is well-established, the evidence regarding bystander interventions in trauma care, particularly following road injury, is less well defined. This scoping review systematically examined the prevalence, nature, and impact of bystander interventions following trauma, with particular emphasis on road traffic injuries, and identified the factors that influence bystander behaviour. Methods: This scoping review followed PRISMA-ScR guidelines. A systematic search was conducted across MEDLINE, CINAHL, and Psychology & Behavioural Sciences Collection via the EBSCO Host platform, supplemented by hand searches using Google Scholar and reference screening. Studies were included if they explored pre-hospital trauma interventions by laypersons or professional bystanders (e.g., police, fire personnel) outside formal healthcare systems. Data were extracted using a structured template, and findings were synthesised descriptively using the Road Injury Chain of Survival as an analytical framework. Results: A total of 33 studies were included, spanning high-income and low-resource settings. Bystanders were frequently present at trauma scenes but intervention rates ranged significantly depending on context. Bystander interventions (aside from contacting EMS) most commonly included scene safety, patient positioning, and transport, while hypothermia prevention was often missed. Evidence from LMICs demonstrated that structured training programmes for lay first responders led to significant reductions in trauma-related mortality. In contrast, evidence from high-income countries (HICs) showed mixed results, particularly in relation to transport outcomes. Key factors influencing bystander behaviour included prior training, legal protections, psychological barriers, and sociocultural norms. Conclusion: Bystanders have the potential to significantly impact trauma outcomes, particularly in settings where formal EMS systems are limited. Structured training, supportive legislation, and culturally sensitive educational initiatives can enhance bystander engagement and effectiveness. Bystanders should be recognised as integral components of trauma systems, and future research should focus on optimising their contribution across diverse settings.