TOPLINE:

Early clinical deterioration requiring escalation in care occurred in 3.6% of patients in the emergency department (ED), with nearly half of these events occurring while patients were still in the ED. Each additional hour of boarding was associated with an increased risk for deterioration, and 28-day mortality rates were more than threefold higher among patients with deterioration.

METHODOLOGY:

• Researchers conducted a retrospective observational study of 173,168 adults who were admitted to the ED within 4-48 hours of floor-level care (median age, 67 years; 95% non-Hispanic individuals) within an academic health system in the US (2018-2024). The median ED boarding time was 10.3 hours. About 29.5% of patients had hospitalizations in the past year.
• The primary outcome was early clinical deterioration, defined as escalation to ICU or intermediate care within 48 hours.
• Other outcomes included the location of deterioration (ED vs inpatient setting), the severity of deterioration (based on level of care required: ICU vs intermediate care), and 28-day mortality.
• The analysis was adjusted for boarding time, demographic characteristics, comorbidities, vital signs, laboratory values, ED and hospital census, overnight admission, and socioeconomic status.

TAKEAWAY:

• Early clinical deterioration occurred in 3.6% of encounters, with 45% occurring while patients were still in the ED. The median boarding time was longer among those with deterioration than among those without deterioration (12.5 vs 10.2 hours).
• Boarding duration was independently associated with overall deterioration (adjusted odds ratio [aOR], 1.17; 95% CI, 1.10-1.24) and deterioration occurring in the ED (aOR, 1.58; 95% CI, 1.46-1.71), with each additional hour of boarding associated with a 0.8% and 2.4% increase in risk, respectively.
• Additional predictors were care at an academic safety net hospital (aOR, 2.41; 95% CI, 2.17-2.67), overnight admission (aOR, 1.29; 95% CI, 1.21-1.38), and elevated lactate levels (aOR, 1.93; 95% CI, 1.72-2.17).
• The 28-day mortality rate was higher in patients with deterioration than in those without (13.0% vs 3.9%; odds ratio [OR], 3.66; 95% CI, 3.38-3.96). Mortality rates were 17.5% (OR, 5.20; 95% CI, 4.72-5.73) and 8.6% (OR, 2.31; 95% CI, 2.03-2.63) for patients requiring escalation to ICU-level care (1.8%) and those requiring intermediate care (98.2%), respectively.

IN PRACTICE:

"Early clinical deterioration occurs with a meaningful frequency among ED boarders. Boarding duration was independently associated with increased odds of early clinical deterioration, an event known to increase morbidity and mortality. These data underscore the considerable patient safety risks inherent to boarding," the authors wrote.

"Our results underscore the need for real-time deterioration risk monitoring among boarders and support the development of targeted safety measures, including early warning tools and protocols to mitigate risk during prolonged ED stays," they added.

SOURCE:

The study was led by Nicholas W. Rizer, MD, University of Maryland School of Medicine, Baltimore. It was published online on March 19, 2026, in the Annals of Emergency Medicine.

LIMITATIONS:

The use of a single health system may have limited the generalizability of the findings. Variability in admission criteria for ICU and intermediate care may have affected internal and external validity. An escalation-based definition of deterioration may have missed clinically relevant events without a change in level of care. Additionally, the retrospective design limited causal inferences, and residual confounding could not be ruled out. Delays in transfer due to perceived risk may have introduced bias. Staffing data during periods of ED congestion were not available for analysis.

DISCLOSURES:

Funding information was not provided for the study. The authors reported having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.