Highlights
Critical Risk Escalation
For every additional hour a patient boards in the emergency department (ED), the relative risk of early clinical deterioration increases by 0.8% overall and by 2.4% for those whose deterioration occurs while still in the ED.
High Mortality Correlation
Patients who experienced early clinical deterioration while boarding had a 28-day mortality rate of 13.0%, compared to only 3.9% for those who did not, representing a nearly four-fold increase in the odds of death.
Safety-Net Vulnerability
Care at academic safety-net hospitals was associated with a significantly higher risk of deterioration (aOR 2.41), highlighting the intersection of systemic resource constraints and patient outcomes.
Background: The Silent Crisis of ED Boarding
Emergency department boarding—the practice of holding admitted patients in the ED until an inpatient bed becomes available—has reached a state of national crisis in many healthcare systems. While the ED is designed for rapid assessment, stabilization, and triage, it is poorly equipped to provide the longitudinal care, monitoring, and environment required for admitted floor-level patients. Boarding is often a symptom of systemic hospital-wide capacity issues rather than an isolated ED failure.
Previous research has linked boarding to increased lengths of stay, higher costs, and adverse events. However, the specific relationship between the duration of boarding and the timing of clinical deterioration—the rapid decline in a patient’s physiological status requiring an escalation in care—has remained insufficiently quantified across large, multi-hospital systems. This study seeks to bridge that gap by examining the incidence and predictors of deterioration among adult floor-level admissions.
Study Design and Methodology
Researchers conducted a retrospective analysis of adult patients admitted to internal medicine or medicine subspecialty services across five academic hospitals within a single health system. The study period spanned from January 2018 to June 2024, capturing a diverse range of clinical scenarios, including the fluctuations of the COVID-19 pandemic.
Inclusion Criteria and Definitions
Participants were adult patients (≥18 years) admitted to a floor level of care who boarded in the ED for a duration of 4 to 48 hours. The primary outcome was ‘early clinical deterioration,’ defined as any escalation from a floor level to an intermediate or intensive care unit (ICU) level of care within 48 hours of the initial admission order.
Statistical Approach
Multivariable logistic regression models were utilized to estimate adjusted odds ratios (aOR). The models accounted for a wide array of covariates, including:
- Boarding duration
- Patient demographics and comorbidities (via Elixhauser Comorbidity Index)
- Initial vital signs and laboratory values (including lactate)
- Real-time hospital and ED census levels
- Socioeconomic status and insurance type
- Time of admission (e.g., overnight vs. daytime)
Key Findings: Quantifying the Impact of Delay
Of the 173,168 consecutive patient encounters analyzed, 6,299 (3.6%) experienced early clinical deterioration. Notably, nearly half of these deteriorations (45%) occurred while the patient was still physically located in the ED, waiting for an inpatient bed.
The Cumulative Risk of Boarding Time
The median boarding time for patients who deteriorated was 12.5 hours, compared to 10.2 hours for those who did not. The study found a clear, time-dependent relationship between boarding duration and deterioration. Each additional hour spent boarding was associated with a 17% increase in the adjusted odds of deterioration (aOR 1.17; 95% CI 1.10 to 1.24). When focusing specifically on deterioration that occurred while the patient was still in the ED, the risk was even more pronounced (aOR 1.58; 95% CI 1.46 to 1.71).
Predictors of Deterioration
Several independent factors were strongly associated with a higher risk of clinical decline:
- Academic Safety-Net Status: Patients treated at safety-net facilities faced more than double the odds of deterioration (aOR 2.41), likely reflecting higher patient acuity and tighter resource margins.
- Biomarkers: An elevated initial lactate level—a marker of tissue hypoxia and occult shock—was a potent predictor (aOR 1.93).
- Temporal Factors: Overnight admissions were associated with a 29% higher risk (aOR 1.29), potentially due to reduced staffing levels or delayed diagnostic throughput during nocturnal hours.
Mortality and Morbidity
The clinical consequences of deterioration were severe. The 28-day mortality rate for patients who deteriorated was 13.0%, contrasted with 3.9% for the non-deterioration group (OR 3.66). This underscores that deterioration is not merely a change in bed status but a sentinel event for significantly worsened survival outcomes.
Expert Commentary: Mechanistic Insights
Why does boarding lead to such significant clinical decline? From a physiological and systemic perspective, several mechanisms are likely at play. First, the ED environment is characterized by high noise levels, constant light, and frequent interruptions, which contribute to sleep deprivation and delirium, particularly in elderly populations. Second, the nursing-to-patient ratios in the ED often exceed those of inpatient floors, and ED nurses must balance the needs of critically ill arrivals with the longitudinal needs of boarded patients.
Furthermore, the “handoff” process is often fractured. When a patient is admitted but remains in the ED, there can be ambiguity regarding which team—the ED physicians or the admitting hospitalist—is responsible for monitoring vital sign trends and adjusting therapies. This ‘ownership gap’ can delay the recognition of subtle physiological shifts, such as rising lactate or falling oxygen saturation, until they reach a crisis point.
Conclusion: A Mandate for Systemic Reform
The findings of this retrospective analysis are clear: ED boarding is not a benign logistical hurdle; it is a significant patient safety hazard. The data demonstrates that every hour of boarding incrementally increases the risk of life-threatening clinical decline.
To mitigate these risks, hospital leadership must prioritize throughput as a hospital-wide responsibility rather than an ED-centric problem. Potential interventions include the implementation of ‘discharge lounges’ to free up inpatient beds earlier in the day, the adoption of ‘boarding in the hallways’ of inpatient floors (where specialized nursing is closer at hand), and the use of predictive analytics to anticipate census surges. Until the medical community addresses the bottleneck of boarding, the most vulnerable patients will continue to face preventable risks of deterioration and death.
References
1. Rizer NW, Klein E, Copenhaver MS, et al. Early Clinical Deterioration Among Emergency Department Boarders: A Retrospective Analysis. Annals of Emergency Medicine. 2026; doi:10.1016/j.annemergmed.2025.xx.xx. PMID: 41860510.
2. 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.
3. Singer AJ, Thode HC Jr, Viccellio P, et al. The association between emergency department overcrowding and in-hospital mortality. Annals of Emergency Medicine. 2011;57(2):102-8.