Critically injured patients have experienced delays in being transported to hospitals during Mass Casualty Incidents (MCIs). Extended pre-hospital times (PHTs) are associated with increased mortality. It is not clear which factors affect overall PHT during an MCI. This systematic review aimed to investigate PHTs in trauma-related MCIs and identify factors associated with delays for triaged patients at incident scenes.

This systematic review was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Web of Science, CINAHL, MEDLINE, and EMBASE were searched between January and February 2022 for evidence. Research studies of any methodology, and grey literature in English, were eligible for inclusion. Studies were narratively synthesized according to Cochrane guidance.

Of the 2025 publications identified from the initial search, 12 papers met the inclusion criteria. 6 observational cohort studies and 6 case reports described a diverse range of MCIs. PHTs were reported variably across incidents, from a median of 35 minutes to 8 hours, 8 minutes. Factors associated with prolonged PHT included: challenging incident locations, concerns about scene safety, and adverse decision-making in MCI triage responses. Casualty numbers did not consistently influence PHTs. Study quality was rated moderate to high.

PHT delays of more than 2 hours were common. Future MCI planning should consider responses within challenging environments and enhanced timely triage decision-making.