Cost of Emergency Department Boarding for Hospitalized Patients in a Statewide Medical System
Conditions: Stroke (CVA) or TIA, Diabetes, Asthma (Diagnosis), COPD (Chronic Obstructive Pulmonary Disease), Sepsis, Hypertension, Heart Failure, Pneumonia, Urinary Tract Infection (Diagnosis), Chest Pain, Psychiatric Disorder, Sickle Cell Disease (SCD)
Sponsor: University of Maryland, Baltimore

Cover Page 
Official Study Title: Cost of Emergency Department Boarding for Hospitalized Patients 
in a Statewide Medical System 
ClinicalTrials.gov Identifier (NCT): NCTXXXXXXXX (pending) 
Document Type: Study Protocol 
Version: 1.0 
Document Date: April 9, 2026 
 
1. Background and Rationale 
Emergency department (ED) boarding—defined as the practice of holding admitted 
patients in the ED while awaiting inpatient bed placement—has reached crisis levels in 
the United States. Prolonged boarding is associated with increased mortality, longer 
hospital length of stay, impaired quality of care, and reduced access for non-admitted 
patients through crowding effects. Despite this, boarding remains common, in part 
because its operational and economic consequences are incompletely understood. 
Most prior studies have relied on billing charges or small-scale time-driven activity-
based costing, both of which have important limitations for system-level decision-
making. This study leverages a large, integrated clinical-operational-financial data 
warehouse within the University of Maryland Medical System (UMMS) to quantify the 
scope, predictors, and cost consequences of ED boarding using direct variable cost 
data—metrics familiar to hospital administrators and reflective of real resource 
utilization. 
Understanding how patient factors affects risk of boarding, how boarding affects costs 
for admitted patients, and how boarding environments affect all ED patients, is critical 
to informing hospital throughput strategies and policy decisions, particularly within 
Maryland’s global budget environment. 
 
2. Study Objectives and Specific Aims 
Overall Objective 
To characterize the scope of ED boarding and quantify its financial and system-level 
impacts across a multi-hospital academic health system. 

Aim 1: Define the scope and burden of ED boarding 
Research Question: What patient, clinical, and system-level factors are associated 
with longer ED boarding times across UMMS hospitals? 
Aim 2: Quantify the effect of ED boarding on hospitalization costs for 
admitted patients 
Research Question: How does ED boarding time affect total and daily direct variable 
hospitalization costs among admitted patients? 
Aim 3: Determine the impact of ED boarding on patients exposed to 
crowded ED environments 
Research Question: How do boarding-heavy ED environments affect care processes, 
resource utilization, and outcomes for non-admitted ED patients? 
 
3. Study Design 
This is a retrospective, multi-site observational cohort study using administrative, 
clinical, operational, and cost data from UMMS emergency departments between 2022 
and 2025. 
 
4. Study Setting 
The study will include ED encounters across multiple UMMS hospitals, including 
academic, community, suburban, and rural sites. UMMS hospitals vary in size, 
capacity, and specialty services, allowing examination of boarding across 
heterogeneous practice environments. Single site studies at the flagship academic 
medical center may serve as pilots for system-wide analysis.  
 
5. Study Population 
Inclusion Criteria 
• Adults aged ≥18 years 
• ED encounters resulting in inpatient or observation admission 
• Admission to services that routinely assume clinical responsibility for boarding 
patients 
Exclusion Criteria 
• Pediatric patients 

• Transfers from outside facilities 
• Admissions directly to ICU or intermediate care units when boarding 
responsibility does not remain with the ED 
• Admissions to specialty services that do not manage boarded patients 
 
6. Definitions and Key Variables 
Boarding Time 
Time (hours) from placement of the admission order to physical departure from the ED. 
Boarding Categories 
• <4 hours (reference, consistent with Joint Commission recommendation) 
• 4–12 hours 
• 12–24 hours 
• > 24 hours 
Primary Cost Measures 
• Total direct variable cost per hospitalization 
• Daily direct variable cost (total cost divided by hospital length of stay) 
Boarding Environment Metrics (Aim 3) 
• Boarding Density Ratio: Proportion of ED beds occupied by boarders during a 
patient’s ED stay 
• Boarding-to-Census Proportion: Ratio of boarded patients to total ED census 
Additional outcomes for exploratory analysis 
• Boarding Percentage: Proportion of hospitalization time spent as ED boarder 
 
 
7. Data Sources 
• Epic Electronic Health Record: timestamps, diagnoses, procedures, 
demographics 
• Health Performance Manager (HPM): direct variable cost data and cost 
subcomponents 
• ED Universe Data Warehouse: integrated, curated, relational clinical and 
operational data 

• Epic Clarity Queries: supplementary social, behavioral, and comorbidity 
variables 
 
8. Outcomes by Aim 
Aim 1 
• Boarding duration (continuous and categorical) 
• Proportion of encounters exceeding boarding thresholds 
• Proportion of hospitalization spent boarding 
Aim 2 
• Total direct variable hospitalization costs 
• Daily direct variable hospitalization costs 
Aim 3 
• ED length of stay 
• ED direct variable costs 
• Care quality metrics (e.g., door-to-provider time) 
• Downstream utilization (e.g., 30-day ED revisits) 
 
9. Ethical Considerations 
This study has IRB approval (UMB IRB #HP-00112665) with a waiver of informed 
consent for secondary analysis of existing clinical data. The study qualifies as minimal 
risk. All analyses will be conducted on secure institutional servers with access 
restricted to authorized study personnel. 
 
10. Dissemination 
Results will be disseminated through peer-reviewed journals, academic conferences, 
and presentations to UMMS leadership and policy stakeholders. Only aggregate, de-
identified data will be reported.