Clinical and Operational Effects of Emergency Department Crowding: A Systematic Review

Emergency department (ED) crowding, defined as a mismatch between ED capacity and patient care demands, remains a global challenge linked to delays in care, reduced quality of services, and increased risk of adverse outcomes. This review synthesized thirteen observational studies evaluating the effects of ED crowding on patient outcomes, care processes, and healthcare system performance, including mortality, delays in assessment and treatment, diagnostic and therapeutic timeliness, boarding duration, ED and inpatient length of stay, readmissions, errors, and staff-related impacts. Findings showed that ED crowding consistently resulted in delayed clinical processes, particularly analgesia administration, antibiotic initiation, stroke evaluation, trauma care, and sepsis management, alongside increased ED and inpatient length of stay, higher rates of hospital-acquired complications, diagnostic delays, and reduced adherence to evidence-based practices. Reports on mortality were inconsistent, with some studies identifying an association and others finding no independent effect after adjusting for illness severity, reflecting variability in study design and measurement. Overall, ED crowding was associated with operational strain, increased admission rates, and heightened resource utilization. These findings indicate that ED crowding adversely affects the timeliness and quality of emergency care and contributes to broader system inefficiencies, underscoring the need for coordinated strategies focused on improving patient flow, increasing bed capacity, and reducing boarding to mitigate its impact.