Development of an Atlas for US Pediatric Acute Care

Pediatric acute care in the US is highly regionalized. Existing geographic frameworks to measure acute care patterns were developed based on adults and do not reflect pediatric use patterns.

To develop a national US atlas of pediatric acute care regions.

This was a cross-sectional study of Medicaid data from January 2021 to December 2022, with analysis from April 2024 to June 2025, of US acute care hospitals. Emergency and inpatient encounters among youth younger than 16 years enrolled in Medicaid or the Children's Health Insurance Program, comprising more than half of US youths, were included.

The primary outcome was modularity, a measure of how well an atlas fits pediatric use patterns. Using network analysis, pediatric emergency service areas (PESAs) were derived capturing home-to-hospital care seeking and pediatric emergency referral regions (PERRs) capturing interhospital referrals. Modularity, proportion of encounters staying within region, size, and hospital counts between atlases were compared. Local-level comparisons included PESAs, Dartmouth Atlas hospital service areas (HSAs), and pediatric HSAs (PHSAs) derived using Dartmouth methods. Referral-level comparisons compared PERRs with Dartmouth hospital referral regions (HRRs), pediatric HRRs (PHRRs), and states.

Using data from 27 817 736 encounters (median [IQR] age, 5 [2-10] years; 14 547 400 [52.3%] male) from 4830 hospitals, 835 PESAs and 105 PERRs were identified. PESAs were larger and included more hospitals and youths than HSAs or PHSAs. PERRs were larger (median [IQR], 17 595 [7781-33 251] square miles) and contained more hospitals (median [IQR], 39 [23-59]) and youths (median [IQR], 597 000 [358 000-864 000]) than HRRs (medians [IQRs]: 4822 [2044-9425] square miles, 11 [6-18] hospitals, 146 000 [74 000-282 000] youths) or PHRRs (medians [IQRs]: 8845 [4209-16 608] square miles, 21 [13-35] hospitals, 348 000 [26 703-70 282] youths). States were larger (median [IQR], 50 097 [211 000-638 000] square miles) and had more hospitals (median [IQR], 74 [41-113]), and youths (median [IQR], 961 000 [366 000-1 615 000]) than PERRs. PESAs had the highest local-level modularity. PERRs had the highest referral-level modularity. Among acute care encounters, 89.9% stayed within PESA, 68.6% within HSA, and 80.1% within PHSA. Among referrals, 92.3% stayed within PERR, 73.0% within HRR, 81.9% within PHRR, and 93.4% within state.

The Atlas of Pediatric Acute Care is the first empirically derived, pediatric-specific map of acute care regions spanning the US. Based on actual use patterns, this atlas may serve as a foundation for pediatric research, policy, regional planning, and quality improvement.