The epidemiology of emergency department crowding and boarding in Brazil: a nationwide multicenter study

Abstract Background Emergency department (ED) crowding is associated with adverse patient outcomes, yet its epidemiology remains poorly characterized in low- and middle-income countries. We aimed to characterize ED crowding and boarding across Brazil, including their geographic distribution, temporal trends, hospital characteristics, and association with municipal socioeconomic indicators. Methods We conducted a multicenter observational study using operational data from 160 Brazilian EDs participating in a national quality improvement program between 2019 and 2025. Two ED strain indicators were evaluated: occupancy ratio (ED census divided by designated ED beds) and boarding proportion (admitted patients remaining in the ED divided by total ED census). Descriptive analyses examined temporal trends and geographic variation. Multivariable linear regression assessed associations between municipal Human Development Index (MHDI) and ED strain, with prespecified sensitivity analyses. Results The final cohort comprised 160 hospitals contributing 351 hospital-years and 2,443 hospital-month observations. Median occupancy ratio was 1.03 (IQR, 0.74–1.39), indicating that EDs routinely operated beyond formal capacity. Median boarding proportion was 0.45 (IQR, 0.29–0.63), meaning that nearly half of ED patients were awaiting inpatient beds. Occupancy declined transiently during the COVID-19 pandemic but subsequently returned to pre-pandemic levels, whereas boarding remained consistently elevated throughout the study period. Regional variation was observed, although high ED strain was widespread nationwide. MHDI was not independently associated with either occupancy or boarding in adjusted analyses. Conclusions ED crowding and boarding are pervasive across Brazilian emergency departments, with occupancy routinely exceeding formal capacity and boarding representing a substantial proportion of ED census. These findings suggest that impaired hospital output is a nationwide structural challenge requiring hospital- and system-level strategies to improve patient flow and inpatient capacity.