Untapped Potential for Emergency Department Observation Unit Use: A National Hospital Ambulatory Medical Care Survey (NHAMCS) Study.



Millions of people present to the emergency department (ED) with chest pain annually. Accurate and timely risk stratification is important to identify potentially life-threatening conditions such as acute coronary syndrome (ACS). An ED-based observation unit can be used to rapidly evaluate patients and reduce ED crowding, but the practice is not universal. We estimated the number of current hospital admissions in the United States (US) eligible for ED-based observation services for patients with symptoms of ACS.


In this cross-sectional analysis we used data from the 2011-2015 National Hospital Ambulatory Medical Care Survey (NHAMCS). Visits were included if patients presented with symptoms of ACS (eg, chest pain, dyspnea), had an electrocardiogram (ECG) and cardiac markers, and were admitted to the hospital. We excluded patients with any of the following: discharge diagnosis of myocardial infarction; cardiac arrest; congestive heart failure, or unstable angina; admission to an intensive care unit; hospital length of stay > 2 days; alteplase administration, central venous catheter insertion, cardiopulmonary resuscitation or endotracheal intubation; or admission after an initial ED observation stay. We extracted data on sociodemographics, hospital characteristics, triage level, disposition from the ED, and year of ED extracted from the NHAMCS. Descriptive statistics were performed using sampling weights to produce national estimates of ED visits. We provide medians with interquartile ranges for continuous variables and percentages with 95% confidence intervals for categorical variables.


During 2011-2015 there were an estimated 675,883,000 ED visits in the US. Of these, 14,353,000 patients with symptoms of ACS and an ED order for an ECG or cardiac markers were admitted to the hospital. We identified 1,883,000 visits that were amenable to ED observation services, where 987,000 (52.4%) were male patients, and 1,318,000 (70%) were White. Further-more, 739,000 (39.2%) and 234,000 (12.4%) were paid for by Medicare and Medicaid, respectively. The majority (45.1%) of observation-amenable hospitalizations were in the Southern US.


Emergency department-based observation unit services for suspected ACS appear to be underused. Over half of potentially observation-amenable admissions were paid for by Medicare and Medicaid. Implementation of ED-based observation units would especially benefit hospitals and patients in the American South.





Published Version (Please cite this version)


Publication Info

Navas, Angelo, Billy Guzman, Almujtaba Hassan, Joseph B Borawski, Dean Harrison, Pratik Manandhar, Alaatin Erkanli, Alexander T Limkakeng, et al. (2022). Untapped Potential for Emergency Department Observation Unit Use: A National Hospital Ambulatory Medical Care Survey (NHAMCS) Study. The western journal of emergency medicine, 23(2). pp. 134–140. 10.5811/westjem.2021.8.52231 Retrieved from https://hdl.handle.net/10161/24786.

This is constructed from limited available data and may be imprecise. To cite this article, please review & use the official citation provided by the journal.



Joseph Brian Borawski

Assistant Professor of Emergency Medicine

Alaattin Erkanli

Associate Professor of Biostatistics & Bioinformatics

Areas of research interests include Bayesian hierarchical models for longitudinal data, Bayesian optimal designs, finite mixtures and Mixtures of Dirichlet Processes, Markov transition models, nonparametrics smoothing and density estimation, survival analysis for recurrent-event data, biomarker selection and detecting early ovarian cancer.


Alexander Tan Limkakeng

Professor of Emergency Medicine

Dr. Alexander T. Limkakeng, Jr., MD, MHSc, FACEP is a Professor of Emergency Medicine, Vice Chair of Clinical Research, Director of the Acute Care Research Team, and Director of the Resident Research Fellowship for the Department of Emergency Medicine in the Duke University School of Medicine in Durham, North Carolina.

Dr. Limkakeng has served as chair of the American College of Emergency Physicians (ACEP) Research Committee, and been the Course Director of the ACEP Research Forum from 2016-2018, the largest emergency medical research platform in the nation. He is also the Assistant Director of ACEP’s Emergency Medicine Basic Research Skills course. He was elected to the Nominating Committee of the Society of Academic Emergency Medicine.

As a researcher, Dr. Limkakeng has led multiple clinical trials and interdepartmental sponsored projects and is author on over 100 peer-reviewed manuscripts. These include studies in emergency conditions such as COVID-19, traumatic brain injury, hypertension, heart failure, thrombosis, stroke, envenomations, and septic shock. His research has been funded by grants and contracts totaling over $9 million dollars. He has lectured internationally on acute coronary syndrome, responsible conduct of research, design of clinical trials, and precision medicine in emergency care. He has led Duke’s involvement in NIH-funded research networks and in industry-funded work that led to FDA approval for multiple high-sensitivity cardiac troponin assays and point-of-care COVID-19 diagnostic tests. He has servesd as Co-PI for the Duke U24 Hub in the NIH Early Phase Pain Investigation Clinical Network (EPPIC-Net) (1U24NS114416) and now serves as a co-PI on the Duke U24 Hub award (1U24NS129498) in the NIH Strategies to Innovate Emergency Care Clinical Trials (SIREN) Network and in the NIH NINDS Strokenet network (1U24NS135250)

His personal research interest is finding new ways to diagnose acute coronary syndrome. In particular, he is interested in novel biomarkers and precision medicine approaches to this problem. The common element throughout this work is a focus on time-sensitive health conditions.

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