Administration & Operations, Admin Ops Literature Review

Emergency Department Boarding: Literature and Strategies Review

Emergency departments across the United States have been plagued with overcrowding. In 2006 the U.S. Institute of Medicine declared crowding a national epidemic.1 Despite well-documented detrimental effects of crowding on patient outcomes, solutions to this problem are scarce, and boarding times continue to increase.

Review of Literature

Emergency (ED) Overcrowding: Evidence-Based Answers To Frequently Asked Questions
This summary article reports that ED crowding is primarily driven by boarding, focusing on downstream consequences. Some of the major consequences discussed include: 

  1. In a retrospective cross-sectional study, it was found that sick people wait too long to receive care – only 67% of acutely ill patients were seen within the recommended times in the U.S.2
  2. In a retrospective review of presentations and admissions, boarding was found to increase the total length of stay in the hospital by approx. one extra day when patients are boarded in the ED vs. inpatient units.3-4
  3. A retrospective cohort study and prospective collection of results from the National Emergency Department Overcrowding Scale (NEDOCS) shed light on the fact that boarding increases walkout, sometimes of patients needing admission.5-7
  4. Prospective, observational; retrospective cohort, and cross-sectional analytical studies have been performed that demonstrated how overcrowding reduces the quality of care, increases medical errors, leads to ambulance diversion, and increases mortality.8-15
  5. Retrospective and prospective cohort studies have estimated that financially each walkout from the ED represents about $600-800 in lost revenue.16-17

Authors conclude with several potential solutions, including an increase in the number of hospital beds, adding a hospitalist focused on bed management, smoothing electives surgical cases, increasing weekend discharges, and functioning at full capacity protocol (moving ED hallway patients to inpatient hallways). 

Solutions To Emergency Department "Boarding" And Crowding Are Underused And May Need to Be Legislated
This paper presents evidence that ED crowding is a byproduct of boarding rather than uninsured patients seeking non-emergency care. Boarding is a systemic problem of hospital flow. The following are possible strategies to address some causes for boarding:

  1. Falvo et al., found moving patients to inpatient units within 120 hours increased the functional capacity of their ED by 10,397 hours.18 
  2. Bernstein et al., in a literature review found an increased risk of in-hospital mortality, longer times to treatment for with pneumonia or acute pain, and a higher probability of patients leaving unseen or against medical advice.19 
  3. Proudlove et al., suggest that, according to queuing theory, bottlenecks in a system form when capacity reaches 85-90%, decreasing efficiency. This holds true for EDs.20 
  4. Evidence suggests moving boarding ED patients to inpatient hallways alleviate crowding without affecting patient safety, and is preferred by patients.21,22

The paper concludes that if the above strategies do not work, promoting patient education may be necessary to lead to policy change. Alternative strategies include advocating for the Center for Medicare and Medicaid Services (CMS) to adopt a pay for performance arrangement that imposes penalties to hospitals if they fail to reduce wait times.

Effect of an ED managed acute care unit on ED overcrowding and emergency medical services diversion
This prospective observational single site study collected data for an ED-managed acute care unit (ACU, or observation unit). Of 1,589 studied patients (14.5% of ED volume), 33%  were admitted for post-ED management, 20% for admission processing and the rest of primary evaluation. Patients who left without being seen decreased from 10.1% of ED census before the ACU's opening to 5.0% (4.2%-6.2%) 10 weeks after. Ambulance diversion went from 6.7 hours per 100 patients to 2.8 hours per 100 patients (p <0.05), with a 40% decrease comparing the six months pre-ACU to 2 months post-ACU (p<0.05). Authors conclude that an ED-managed ACU can have a significant positive impact on ED overcrowding and ambulance diversion.23

Progressive prediction of hospitalization in the emergency department: uncovering hidden patterns to improve the flow
Authors utilized data from patient encounters to develop a predictive model identifying hospitalizations and discharges to improve patient flow and clinical operations by minimizing wait times. This retrospective cross-sectional study is based out of a large tertiary hospital. Through a logistic regression it predicted 94% of hospitalizations and 90% of discharges as early as 1 hr of patient's presentation to the ED. This paper concludes that similar models can be implemented into electronic medical record systems to optimize ED overcrowding and boarding issues.24 

Summary of Literature 
Emergency departments have struggled with overcrowded conditions for decades, much of the problem stems from hospitals' institutional structure and operational inefficiencies, leading to ED boarding – the primary driver of crowding. Despite the adverse impact ED crowding on patient outcomes and quality, solutions remain scarce and understudied. Certain strategies have been identified including increased availability of diagnostic tests and procedures over the weekends/ and night, smoothing surgical schedules and opening of ED-ACU (observation units). Additionally improving flow may be achieved through "pooling" of beds among different hospital units and/or moving ED hallway admitted patients to inpatient hallways can be considered. Recent work has focused on highlighting the financial repercussions of boarding; when EDs go over capacity it causes ambulances to be diverted and increases the number of patient walk-outs. Hospital leadership will need to take a proactive approach to address these critical issues.

Looking Forward/What's Next
Unique prediction models have also been designed to address ED overcrowding and boarding issues, though but it is unclear whether earlier identification of inpatient admission would truly improve ED boarding and overcrowding issues, as this is a complex process that requires institutional buy-in. Hospitals are required to report ED crowding measures to CMS and will have changing reimbursement compensations tied to it, incentivising solutions.

Other Recommended Literature

  1. Hoot NR, Aronsky D. Systematic review of emergency department crowding: causes, effects, and solutions. Ann Emerg Med. 2008;52(2):126-136.
  2. Li K, et al. Crowding and Boarding. In Schlicher N, Haddock A, eds. Emergency Medicine Advocacy Handbook, 4th ed. Emergency Medicine Residents' Association; Dallas, TX. 2019.
  3. Emergency Department Crowding: High Impact Solutions. Emergency Medicine Practice Committee. American College of Emergency Physicians.
  4. Joshi AU, Randolph FT, Chang AM, et al. Tele-intake (improved LWBS but no overall impact on flow). Acad Emerg Med. 2020;27(2):139-147.
  5. Kobayashi KJ, Knuesel SJ, White BA, et al. Impact on Length of Stay of a Hospital Medicine Emergency Department Boarder ServiceJ Hosp Med. 2019;14:E1-E7.

EMRA Administration & Operations Committee Links, Guides and Opportunities


  1. Institute of Medicine. Hospital Based emergency care: at the breaking point. Washington (DC): National Academies Press; 2006. 
  2. Horwitz LI, Green J, Bradley EH. US emergency department performance on wait time and length of visit. Ann Emerg Med. 2010; 55(2):133-141.
  3. Krochmal P, Riley TA. Increased health care costs associated with ED overcrowding. Am J Emerg Med. 1994; 12(3):265-266.
  4. Liew D, Liew D, Kennedy MP. Emergency department length of stay independently predicts excess inpatient length of stay. Med J Aust. 2003; 179(10): 524-526.
  5. Richardson DB. The access-block effect: relationship between delay to reaching an inpatient bed and inpatient length of stay. Med J Aust. 2002;177(9):492-5.
  6. Weiss SJ, Ernst AA, Derlet R, et al. Relationship between the National ED Overcrowding scale and the number of patients who leave without being seen in an academic ED. Am J Emerg Med. 2005;23:288-94.
  7. Richardson DB, Bryant, M. Confirmation of association between overcrowding and adverse events in patients who do not wait to be seen. Acad Emerg Med. 2004;11(5):462.
  8. Cowan RM, Trzeciak S. Clinical review: emergency department overcrowding and the potential impact on the critically ill. Crit Care. 2005;9(3):291-5.
  9. Kulstad EB, Sikka R, Sweis RT, et al. Overcrowding is associated with an increased frequency of medication errors. Am J Emerg Med. 2010; 28(3):304-9.
  10. Chalfin DB, Trzeciak S, Likourezos A, et al. Impact of delayed transfer of critically ill patients from the emergency department to the intensive care unit. Crit Care Med. 2007;35(6):1477–83.
  11. Singer AJ, Thode HC Jr, Viccellio P, et al. The association between length of emergency department boarding and mortality. Acad Emerg Med. 2011; 18(12):1324-1329.
  12. Richardson DB. Increase in patient mortality at 10 days associated with emergency department overcrowding. Med J Aust. 2006;184(5):213-216.
  13. Burt CW, McCaig LF. Staffing, capacity, and ambulance diversion in emergency departments: United States, 2003–04. Adv Data. 2006; 376: 1-23.
  14. Olshaker JS, Rathlev NK. Emergency Department overcrowding and ambulance diversion: the impact and potential solutions of extended boarding of admitted patients in the emergency department. J Emerg Med. 2006;30(3):351–356.
  15. Nicholl J, West J, Goodacre S, et al. The relationship between distance to hospital and patient mortality in emergencies: an observational study. Emerg Med J. 2007; 24(9):665–8.
  16. Falvo T, Grove L, Stachura R, et al. The opportunity loss of boarding admitted patients in the emergency department. Acad Emerg Med. 2007; 14(4):332-337.
  17. Bayley MD, Schwartz JS, Shofer FS, et al. The financial burden of emergency department congestion and hospital crowding for chest pain patients awaiting admission. Ann Emerg Med. 2005;45(2):110-117.
  18. Falvo T, et al. The opportunity loss of boarding admitted patients in the emergency departmentAcad Emerg Med. 2007;14(4):332-337.
  19. Bernstein SL, Aronsky D, Duseja R, et al. The effect of emergency department crowding on clinically oriented outcomes. Acad Emerg Med. 2009;16(1):1-10.
  20. Proudlove NC, Gordon K, Boaden R. Can good bed management solve the overcrowding in accident and emergency departments? Emerg Med J. 2003;20:149-155.
  21. Viccellio A, Santora C, Singer AJ  Thode HC, Henry MC. The association between transfer of emergency department boarders to inpatient hallways and mortality: a 4-year experience. Ann Emerg Med. 2009;54(4): 487-489.
  22. Garson C, Hollander JE, Rhodes KV, Shofer FS, Baxt WG, Pines JM . Emergency department patient preferences for boarding locations when hospitals are at full capacity. Ann Emerg Med. 2008;51:9-12.
  23. Kelen GD, Scheulen JJ, Hill PM. Effect of an emergency department (ED) managed acute care unit on ED overcrowding and emergency medical services diversion. Acad Emerg Med. 2001;8(11):1095-1100. 
  24. Barak-Corren Y, Israelit SH, Reis BY. Progressive prediction of hospitalisation in the emergency department: uncovering hidden patterns to improve patient flow. Emerg Med J. 2017;34(5):308-314.

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