Estimating Queue Externalities in the Emergency Department

Emergency Departments (EDs) operate according to the principle that high-acuity patients should be treated as quickly as possible, ahead of low-acuity patients. Prioritizing treatment for high-acuity patients saves both lives and money, as even small delays in a high-acuity patient’s treatment can negatively affect mortality, recovery times and associated medical costs. In response, many Operations Management studies choose to model EDs and other hospital facilities as preemptive priority queues with multiple acuity classes (Fomundam and Herrmann, 2007; Green, 2006). Such models frequently assume that a high-acuity patient’s treatment will only be delayed if a facility is currently overloaded with other high-acuity patients. In practice, however, ED crowding by low-acuity patients correlates with significantly increased wait times for even high-acuity patients, indicating that preemptive priority models oversimplify the reality on the ground at many EDs (McCarthy et al., 2009).