What emergency department length of stay reveals about aging-related vulnerability and declining resilience

Emergency department (ED) length of stay (LOS) is associated with adverse outcomes and increases with age, but the extent to which this reflects differences beyond triage acuity is unclear. Emergency department (ED) length of stay (LOS) is associated with adverse outcomes and increases with age, but the extent to which this reflects differences beyond triage acuity is unclear.We conducted a retrospective cohort study of adult ED visits at a tertiary hospital in Hungary between 2016 and 2023 (n = 188,082). Triage data have been available from 2019 onward. LOS was modelled using gamma regression, adjusting for age, triage category, sex, season, and an age-triage interaction, with sensitivity analyses incorporating additional operational covariates. Admission and ED mortality were analysed using multivariable logistic regression. ED LOS increased progressively with advancing age across all triage categories. Mean LOS rose from 5.9 h in patients <65 years to 9.7 h in those ≥85 years (+64%). Age remained independently associated with longer LOS after adjustment (rate ratio per year 1.005, 95% CI 1.004-1.006), with a significant age-triage interaction (p < 0.001). Higher-acuity triage assignments were more frequent with age, yet age-related LOS differences persisted within each triage category. ED mortality increased markedly with advancing age. These patterns were consistent across sensitivity analyses. Advancing age was associated with longer ED LOS across all triage categories, independent of triage acuity, indicating that age-related differences in emergency care trajectories extend beyond differences in initial acuity. The persistence of LOS prolongation across triage strata suggests that standard acuity-based assessment does not fully capture aging-related vulnerability. From a geroscience perspective, ED LOS may reflect as a routinely available, system-level signal of aging-related vulnerability beyond triage acuity, with direct relevance for early risk identification, geriatric care pathways, delirium prevention, and health system planning.