Highlight
- A national retrospective study of over 6.7 million emergency department visits examined the relationship between time spent in ED and mortality within 30 days post-discharge or admission.
- Longer durations in Type 1 emergency departments for nonimmediate acuity patients associated with progressively higher adjusted odds ratios for all-cause 30-day mortality compared to a 2-hour reference.
- Adjusted odds of death rose from 1.1 times at 3 hours to over 2 times at 12 hours, after controlling for confounders, emphasizing potential risks linked to prolonged ED stay.
- While a direct causal relationship remains unclear, the findings underscore the critical need for further research elucidating the mechanisms driving post-ED mortality.
Study Background
Emergency departments (EDs) serve as vital access points for acute healthcare, particularly for conditions requiring urgent but not immediate life-saving interventions. Type 1 EDs in England provide consultant-led, 24-hour specialist services with full resuscitation capabilities, handling a diverse patient volume ranging from minor ailments to critical emergencies. Overcrowding and prolonged stays in EDs have emerged as a considerable challenge globally, with implications for operational efficiency, patient experience, and clinical outcomes.
Previous studies have linked extended ED wait times to adverse effects such as delayed treatment and increased hospital length of stay. However, definitive evidence quantifying the relationship between time spent in the ED and mortality after discharge or admission remains sparse. Understanding whether prolonged ED stay independently predicts short-term mortality could inform healthcare policy and resource allocation aimed at improving emergency care quality and patient safety.
Study Design
This was a cross-sectional, retrospective observational study utilizing national linked administrative datasets covering Type 1 ED visits in England between March 21, 2021, and March 31, 2022. The cohort included 6,721,179 individuals aged across all groups presenting with nonimmediate acuity—that is, patients who were stable enough not to require immediate resuscitation or life-saving procedures during initial assessment.
Participants were followed until their discharge home or admission to inpatient care. The exposure of interest was time spent in the ED, measured continuously but analyzed categorically compared to a 2-hour reference duration. The primary endpoint was all-cause mortality within 30 days after leaving the ED alive.
Logistic regression models adjusted for potential confounders, including demographic factors (age, sex, ethnicity), clinical characteristics, and visit attributes, were employed to estimate the association between ED time and subsequent death risk.
Key Findings
The average age of the study population was 41.3 years, with a slight female predominance (52.6%) and majority White ethnicity (81.4%). Overall, 1.3% of patients died within 30 days post-ED visit.
Multivariable analysis revealed a graded association between longer ED stay and increased odds of 30-day mortality. Compared to those who spent 2 hours in the ED, adjusted odds ratios (aOR) for death were:
- 1.1 (95% CI: 1.07 to 1.14) at 3 hours
- 1.6 (95% CI: 1.48 to 1.68) at 6 hours
- 1.9 (95% CI: 1.80 to 2.03) at 9 hours
- 2.1 (95% CI: 2.02 to 2.28) at 12 hours
This incremental risk trajectory suggests that even moderate prolongation of ED time is associated with clinically meaningful increases in mortality risk within one month. These findings persisted after rigorous adjustment for confounders, indicating a robust relationship.
Expert Commentary
The study provides important population-level evidence linking prolonged ED stay to increased short-term mortality for patients not classified as requiring immediate resuscitation. The large sample size and use of national linked datasets enhance the generalizability of findings in the context of the English healthcare system.
However, the observational design limits causal inference. Reverse causality or residual confounding may partially explain the association; for example, sicker patients might experience longer ED stays due to diagnostic complexity or delays in inpatient bed availability, thereby increasing mortality risk independent of time spent per se.
Moreover, unmeasured variables such as comorbidities, severity scores, or social determinants could confound results. The study highlights an urgent need for prospective, granular research to delineate biological or system-level mechanisms underpinning this association. Investigations into quality-of-care metrics, ED crowding impacts, and transition of care processes could elucidate actionable targets to reduce post-discharge mortality.
Conclusion
This large observational study underscores a strong association between longer visits in consultant-led, 24-hour Type 1 emergency departments and increased 30-day all-cause mortality among nonimmediate acuity patients. While causality remains unproven, these findings raise critical concerns regarding current ED throughput and discharge processes.
Future research should prioritize identifying causal drivers and differentiating between patient factors and healthcare system contributions to post-ED mortality risk. Interventions aimed at streamlining patient flow and enhancing transitional care may offer potential benefits to improve outcomes for this vulnerable population.
Funding and Registration
The study was conducted by Aston et al. and published in the Annals of Emergency Medicine on July 7, 2026 (PMID: 42412031). Specific funding sources and trial registration details were not provided in the original abstract.
References
- Aston H, Machuel P, Mill N, et al. Association Between Time Spent in the Emergency Department and 30-Day Mortality: A Population-Level Observational Study in England. Ann Emerg Med. 2026 Jul 7. PMID: 42412031.
<li.Hu S, Durbin RJ, et al. Emergency Department Crowding: Causes, Consequences, and Solutions. J Emerg Med. 2018;54(5):655-663.
<li.Morley C, Unwin M, Peterson GM, et al. Emergency department crowding: A systematic review of causes, consequences and solutions. PLoS One. 2018;13(8):e0203316.
<li.King L, Taylor DM. The effects of prolonged wait times in ED on clinical outcomes and patient experience. Emerg Med Australas. 2020;32(1):38-44.