Association between multiday emergency department boarding and higher in-hospital mortality: evidence from Brazil

Emergency department (ED) boarding is a major driver of overcrowding and has been associated with adverse outcomes; however, little is known about the impact of multiday boarding delays, which are common in low- and middle-income countries. Therefore, we aimed to evaluate the association between multiday boarding and in-hospital mortality in a large tertiary hospital in Brazil.

We conducted a retrospective cohort study of adult patients admitted via the ED of Hospital de Clínicas de Porto Alegre between January 2022 and December 2023, using administrative hospital data. ED boarding time was defined as the interval between the admission decision and the patient's physical departure from the ED. Multivariable logistic regression with restricted cubic splines modeled boarding time as a continuous exposure, adjusting for age, sex, and triage acuity.

Among 28 743 admissions, the median boarding time was 1.8 days (interquartile range: 0.6-3.5). In-hospital mortality was 8.36%. Compared with patients in the first boarding quartile (median: 0.19 days), those in the last quartile (median: 4.92 days) had higher adjusted odds of death [odds ratio (OR): 1.15, 95% confidence interval (CI): 1.05-1.25]. At the cohort median (1.8 days), each additional day of boarding was associated with a 6% increase in the odds of in-hospital death (OR: 1.06; 95% CI: 1.02-1.09).

Prolonged ED boarding time was independently associated with increased in-hospital mortality, with no evidence of a safe threshold. Multiday delays represent a modifiable risk factor associated with excess mortality.