This population-level retrospective observational study examined the association between time spent in Type 1 EDs in England and all-cause 30-day mortality among 6.7 million non-immediate acuity patients who survived to discharge or admission (March 2021–March 2022).
1.3% of patients died within 30 days. Compared to a 2-hour ED stay, adjusted odds of 30-day death rose progressively: aOR 1.1 (95% CI 1.07–1.14) at 3 hours, 1.6 (1.48–1.68) at 6 hours, 1.9 (1.80–2.03) at 9 hours, and 2.1 (2.02–2.28) at 12 hours.
- Cross-sectional, observational design cannot establish causality; residual confounding is a major concern. - Study restricted to non-immediate acuity patients in England's Type 1 EDs, limiting generalizability to other settings or higher-acuity presentations. - Reasons for longer stays (e.g., clinical complexity vs. system crowding) were not disentangled, making it unclear whether ED time itself drives mortality.
Prolonged ED stays are linked to meaningfully higher 30-day mortality risk, even in non-immediate patients — but causality is unproven. Clinicians and administrators should treat ED length-of-stay as a potential patient safety signal worth monitoring, while awaiting causal research.
