Unplanned Regionalization and Interstate Dependence in Pediatric Hospital Care.

Importance: Pediatric hospital care is rapidly consolidating in the US, with some states now depending on neighboring states to supply pediatric inpatient services. The extent and nature of this interstate dependence have not been characterized. Objective: To describe cross-state pediatric hospital utilization patterns and quantify the degree of interstate dependence in the New England region. Design, Setting, and Participants: This was a retrospective cross-sectional study of inpatient admissions at all hospitals admitting children (age <15 years) in the New England region and the enclosing border state of New York in 2019. Admissions for mental health, routine newborn care, and pregnancy-related diagnoses were excluded. Data analysis was conducted from July to December 2024. Exposure: Hospitalization location in state or out of state. Main Outcomes and Measures: The source, number, and proportion of out-of-state admissions, bed-days, primary diagnoses, and insurance types in each state in the New England region. Results: Among 28 631 pediatric admissions, 71.1% occurred in Massachusetts, corresponding to 86.8% of bed-days in the region. Of the total admissions, 16 211 (56.7%) were of male children and slightly more than half (16 336 encounters [57.1%]) were of children older than 4 years. The fraction of residents receiving out-of-state care varied from 2.0% in Massachusetts to 65.8% in New Hampshire (median [IQR], 21.5% [11.3%-28.9%]). Massachusetts hospitals served 578 of the 599 primary diagnoses reported in the region and provided 43.5% (36 731) of all hospital days required by residents of other New England states. In all states, privately insured children were more likely than Medicaid enrollees to be admitted to out-of-state hospitals (median [IQR], 30.5% [17.0%-37.2%] vs 15.6% [6.4%-24.7%]; adjusted odds ratio, 2.21 [95% CI, 2.01-2.44]), often for common conditions. Conclusions and Relevance: In this cross-sectional study, pediatric care in New England constituted a de facto regionalized system, with substantial interstate movement of patients and heavy reliance on Massachusetts. These findings highlight an unplanned interdependence that may leave the system vulnerable to disruption. Regional planning and formal coordination among states may be necessary to ensure sustainable access to care. These findings may hold relevance for other regions.