Who is Next: Patient Prioritization Under Emergency Department Blocking

Upon arrival at emergency departments (EDs), patients are classified into different triage levels indicating their urgency. Using data from a large hospital in Canada, we find that within the same triage level, the average waiting time (time from triage to physician initial assessment) of discharge patients is shorter than that of admit patients for middle-to-low acuity patients, suggesting that the order of patients being served deviates from FCFS (first-come-first-served), and to certain extent, discharge patients are prioritized over admit patients. This observation is intriguing as among patients of the same triage level, admit patients—who need further care in the hospital—should be deemed no less urgent than discharge patients who only need treatment at the ED.

To understand how ED decision makers choose the next patient for treatment, we estimate a discrete choice model and find that ED decision makers apply urgency-specific delay-dependent prioritization. Moreover, when ED blocking level is sufficiently low, admit patients are prioritized over discharge patients for high acuity patients, and FCFS is followed for middle-to-low acuity patients. When the risk of ED being blocked becomes sufficiently high, decision makers start to prioritize patients who are less likely to be admitted after treatment at ED, in an effort to avoid further blocking the ED. We then analyze a stylized model to explain the rationale behind decision makers’ prioritization behavior when the ED faces increasing risk of being blocked. We also investigate the impact of such prioritization behavior on ED operational performances and show how to leverage our findings to improve ED waiting time prediction. By testing and highlighting the central role of decision makers’ patient prioritization behaviors, this paper advances our understanding of ED operations and patient flow.

Keywords: Patient Prioritization, ED Blocking, Discrete Choice Model, MDP