Prolonged emergency department boarding is associated with increased aggression and violent incidents in psychiatric patientsLonger wait times in emergency rooms linked to patient aggression

Emergency department (ED) boarding of psychiatric patients has reached unprecedented levels, with mean boarding times exceeding 60 h in some jurisdictions. Prolonged boarding exposes vulnerable patients to adverse events, including aggression and violence, yet the relationship between boarding duration and these outcomes remains poorly characterized. Understanding this association is critical for improving patient safety and informing ED policy. We conducted a systematic review following PRISMA guidelines. We searched SciSpace, Google Scholar, PubMed and Embase for studies published between 2016 and 2026. Eligible studies included psychiatric ED populations with measured boarding duration and reported aggression or violence outcomes. Two reviewers screened paper's titles and abstracts, and when shortlisted, they reviewed the full texts independently. Data on study design, sample characteristics, boarding duration, and aggression outcomes were extracted. We identified 665 records, removed 114 duplicates, and screened 551 unique records. Fourteen full-text papers were assessed for eligibility, and 12 studies met inclusion criteria. Evidence consistently demonstrated a positive association between prolonged ED boarding and increased aggression or violent incidents. Youth with aggressive behaviours experienced 193% longer boarding times than those without aggression. Patients experiencing adverse events including physical assault had boarding times of 35 h compared to 6.5 h for those without such events. Specialized interventions reducing boarding time were associated with decreased violent incidents and reduced use of restrictive interventions. Prolonged ED boarding of psychiatric patients is associated with increased aggression and violence. These findings underscore the urgent need for system-level interventions to reduce boarding times, expand acute psychiatric resources, and implement evidence-based care models that prioritize early therapeutic intervention over prolonged observation in ED settings.