Empirical Studies in Hospital Emergency Departments

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Doctor of Philosophy (PhD)
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Operations & Information Management
Emergency Department
Empirical Studies
Operations Management
Business Administration, Management, and Operations
Health and Medical Administration
Management Sciences and Quantitative Methods
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This dissertation focuses on the operational impacts of crowding in hospital emergency departments. The body of this work is comprised of three essays. In the first essay, "Waiting Patiently: An Empirical Study of Queue Abandonment in an Emergency Department," we study queue abandonment, or "left without being seen." We show that abandonment is not only influenced by wait time, but also by the queue length and the observable queue flows during the waiting exposure. We show that patients are sensitive to being "jumped" in the line and that patients respond differently to people more sick and less sick moving through the system. This study shows that managers have an opportunity to impact abandonment behavior by altering what information is available to waiting customers. In the second essay, "Doctors Under Load: An Empirical Study of State-Dependent Service Times in Emergency Care," we show that when crowded, multiple mechanisms in the emergency department act to retard patient treatment, but care providers adjust their clinical behavior to accelerate the service. We identify two mechanisms that providers use to accelerate the system: early task initiation and task reduction. In contrast to other recent works, we find the net effect of these countervailing forces to be an increase in service time when the system is crowded. Further, we use simulation to show that ignoring state-dependent service times leads to modeling errors that could cause hospitals to overinvest in human and physical resources. In the final essay, "The Financial Consequences of Lost Demand and Reducing Boarding in Hospital Emergency Departments," we use discrete event simulation to estimate the number of patients lost to Left Without Being Seen and ambulance diversion as a result of patients waiting in the emergency department for an inpatient bed (known as boarding). These lost patients represent both a failure of the emergency department to meet the needs of those seeking care and lost revenue for the hospital. We show that dynamic bed management policies that proactively cancel some non-emergency patients when the hospital is near capacity can lead to reduced boarding, increased number of patients served, and increased hospital revenue.

Christian Terwiesch
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