As ED occupancy climbs, so does risk of death

Clinical takeaway: Crowding itself, not just the delays it causes, was linked to worse survival for patients admitted through the ED. A department's patient-to-space ratio offers a quick read on when potential harm is building. 

An emergency physician on a packed shift can feel the danger: every cubicle taken, stretchers parked along corridors, ambulances queuing outside because there is nowhere inside to unload. But executives and policymakers require specific data to act. 

The best-documented harm is delay: long waits and slow transfers to inpatient beds have repeatedly been connected with more patients dying. But now a large prospective study takes the opposite tack, examining whether the simplest measure on offer, arrivals on hand versus places to treat them, offers insights to act upon. 

Each 10% rise in occupancy was tied to a 1% relative increase in 28-day all-cause mortality among adults admitted through the department. The EDs studied averaged 175% occupancy, three patients under care for every two spaces built to hold them. Occupancy tallies everyone in the department, admitted or not, while deaths were measured only among those admitted to the hospital. 

The share of patients treated in corridors and other non-standard spaces was likewise linked to 28-day mortality, and models built on that share flagged risk no better than models built on occupancy. But a patient-to-space ratio takes one count to produce, which the investigators argue makes it the more workable measure for routine reporting. 

The study enrolled 19,034 adults admitted through 134 EDs in Wales, Northern Ireland, and England, sampled across five snapshot periods in 2025. Investigators ran a prospective snapshot cohort design, relating each department's occupancy on the day of care to deaths within 28 days. 

The investigators have built the finding into a risk calculator that lets a department translate its patient-to-space ratio into an estimate of the danger its patients face, and they are taking the results to governments with the aim of shaping emergency care policy. Larger studies will still be needed to tighten the estimate, since the effect the study produced was small and its plausible range wide. 

"We found that increased crowding in emergency departments is associated with increased mortality for patients admitted to hospital," said Ryan McHenry, MBChB, an emergency medicine doctor with the Scottish Ambulance Service's ScotSTAR retrieval division in Glasgow. "This is important because we know that emergency departments are now often very crowded, and reducing that crowding has the real potential to save lives. Overcrowding is a problem in many countries and, although there will be regional differences, this link between overcrowding and patient deaths is likely to hold true around the world." 

Source: McHenry R, et al. (2026 Sep 26) European Emergency Medicine Congress 2026, abstract OA068. The association between emergency department occupancy and mortality: a multi-centre prospective cohort study