Citation: Terning, G.; El-Thalji, I.; Brun, E.C. The Impact of Patient Infection Rate on Emergency Department Patient Flow: Hybrid Simulation Study in a Norwegian Case. Healthcare 2023, 11, 1904. https://doi.org/10.3390/ healthcare11131904 Academic Editors: Tommaso Staniscia, Giuseppe Di Martino and Fabrizio Cedrone Received: 27 April 2023 Revised: 23 June 2023 Accepted: 27 June 2023 Published: 30 June 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). healthcare Article The Impact of Patient Infection Rate on Emergency Department Patient Flow: Hybrid Simulation Study in a Norwegian Case Gaute Terning 1, * , Idriss El-Thalji 2 and Eric Christian Brun 1 1 Departmentof Safety, Economics, and Planning, University of Stavanger, 4036 Stavanger, Norway 2 Department of Mechanical and Structural Engineering and Materials Science, University of Stavanger, 4036 Stavanger, Norway * Correspondence: gaute.terning@uis.no Abstract: The COVID-19 pandemic put emergency departments all over the world under severe and unprecedented distress. Previous methods of evaluating patient flow impact, such as in-situ simulation, tabletop studies, etc., in a rapidly evolving pandemic are prohibitively impractical, time-consuming, costly, and inflexible. For instance, it is challenging to study the patient flow in the emergency department under different infection rates and get insights using in-situ simulation and tabletop studies. Despite circumventing many of these challenges, the simulation modeling approach and hybrid agent-based modeling stand underutilized. This study investigates the impact of increased patient infection rate on the emergency department patient flow by using a developed hybrid agent-based simulation model. This study reports findings on the patient infection rate in different emergency department patient flow configurations. This study’s results quantify and demonstrate that an increase in patient infection rate will lead to an incremental deterioration of the patient flow metrics average length of stay and crowding within the emergency department, especially if the waiting functions are introduced. Along with other findings, it is concluded that waiting functions, including the waiting zone, make the single average length of stay an ineffective measure as it creates a multinomial distribution of several tendencies. Keywords: healthcare; emergency department; patient flow; patient infection rate; COVID-19 pandemic; agent-based hybrid model; multi-agent hybrid model; pandemic decision support 1. Introduction The COVID-19 pandemic has placed a significant burden on the healthcare system since early 2020 and was pronounced by the world health organization (WHO) to constitute a global public health emergency of international concern [1]. Emergency departments had to amend their patient flow policies to concord with the risk of infection and ramifications associated with contracting the virus [2,3]. The emergency department managers had to modify their patient flow policies to deal with the threat of people who may have contracted the SARS-CoV-2, an illness known to be with a high infection rate. In this unprecedented and challenging time, emergency department managers had to change the patient flow operations to adhere to governmental regulations such as social distancing, minimizing personal contact, utilizing personal protective equipment, extra sanitary measures, as well as other organization-specific guidelines [4,5]. The COVID-19 virus, recognized for its rapid mutation rate [6], high infection rate [7], and potential severity in immunocompromised patients [8], has highlighted the importance of proactive threat assessment and analysis, ideally achieving this with maximum flexibility, minimal risk, and cost-effectiveness. The COVID-19 pandemic has renewed focus on patient flow within emergency departments, requiring reconsidering clinical patient management strategies [8–10]. Hospital emergency departments represent multifaceted systems characterized by numerous dynamic parameters, which make the task of assessing the comprehensive Healthcare 2023, 11, 1904. https://doi.org/10.3390/healthcare11131904 https://www.mdpi.com/journal/healthcare