Out-of-State Acute Care Use Among Pediatric Medicaid Enrollees.

Importance: For many US children, the nearest hospital may be out of state. Medicaid coverage differs by state, affecting access across state lines. Objective: To evaluate the frequency of out-of-state acute care use for pediatric patients. Design, Setting, and Participants: This cross-sectional study analyzed acute care hospital data for emergent and inpatient encounters among children younger than 16 years enrolled in Medicaid or the Children's Health Insurance Program (CHIP) in the 2021-2022 Transformed Medicaid Statistical Information System Analytic File database. Analyses were conducted January to July 2025. Exposure: Distance from a state border. Main Outcomes and Measures: The primary outcome was out-of-state care. The percentages of encounters occurring out of state were measured by state, city, and zip code. Logistic regression was used to evaluate the association of out-of-state care use with the log distance from a patient's zip code to the border between states. Results: This analysis included 28 952 692 acute care patient encounters (median [IQR] age, 5.3 [2.0-10.8] years, 52.3% male). Out-of-state care occurred among 820 972 encounters (2.8% [95% CI, 2.8%-2.8%]). Maryland (61 468 of 389 539 [15.8% (95% CI, 15.7%-15.9%)]), Vermont (3625 of 31 101 [11.7% (95% CI, 11.3%-12.0%)]), and West Virginia (18 455 of 168 151 [11.0% (95% CI, 10.8%-11.1%)]) had the highest percentages of out-of-state care. The city from which the highest number of children accessed care out of state was Kansas City, Missouri (13 327 of 84 181 encounters [15.8% (95% CI, 15.6%-16.1%)]). Out-of-state care use was more common in rural areas (4.4% [95% CI, 4.3%-4.4%]) compared with urban areas (2.7% [95% CI, 2.7,%-2.7%]). For every 2-fold increase in distance from a state border, crossing a border for care was 34.2% (95% CI, 34.2%-34.3%) less likely. Among children within 1 mile of a state border, 10.0% (95% CI, 9.9%-10.0%) received care out of state. Conclusions and Relevance: Findings from this cross-sectional study of Medicaid and CHIP enrollees indicated that out-of-state acute care use was uncommon overall but more common near state borders. Certain states and cities had high rates of out-of-state acute care use. Changes to Medicaid reimbursement could affect patients' ability to access cross-border care.