“…Patient choice is a large driver of variation in healthcare use, and nowhere is this Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/hjdsi more evident in patterns of emergency department use, 9 where specific patient characteristics have been linked to a higher probability of using the ED for care [10]. Prior patient-level studies have demonstrated several demographic and socioeconomic factors are associated with high ED utilization, such as race, poverty, and insurance status [10][11][12]. However, these studies have not considered that these characteristics may have varying effects in different geographic regions [13].…”