An Analysis of Ambulance Transport and Out-of-Network Emergency Department Utilization in an Accountable Care Organization

For hospital-affiliated accountable care organizations (ACOs), emergency care represents a unique challenge for coordination of care and a major source of ACO leakage. The authors analyzed emergency department (ED) visits among ACO members to assess the potential impact of ambulance transport on the use of in-network versus out-of-network EDs. To better understand factors influencing the use of in-network versus out-of-network EDs, 2018 claims data from members of a regional subset of a large ACO in the greater Boston area were analyzed. Within this population, multivariable logistic regression was used to assess the relationship between ambulance transport as well as demographic factors, insurance type, and hospital distance on the use of in-network versus out-of-network EDs. Arrival to an ED via ambulance was found to be significantly associated with reduced odds of presenting to an in-network ED compared to arriving by private transportation (odds ratio 0.70, 95% confidence interval: 0.58-0.85). Age older than 65 years, commercial insurance (relative to Medicare), proximity to an in-network ED, and distance from an out-of-network ED also were significantly associated with use of in-network EDs relative to out-of-network EDs. Given the central role of the ED as a primary source of hospital admissions in the United States, emergency care represents a key potential target for interventions aimed at reducing patient leakage. Future efforts should aim to identify and evaluate new ways that emergency medical services can be leveraged to promote effective care coordination.