Differences in EMS Calls, Delays, and Payer Types in U.S. Southern Border Counties and Non-Border Counties

This study aimed to address the gap in understanding of how the emergency medical services (EMS) experience differs in border counties compared to non-border counties by examining differences between EMS provision in a matched comparison to identify challenges and experiences that result primarily from EMS agency or department location along the United States (U.S.)-Mexico border.

The retrospective observational study analyzed secondary National Emergency Medical Services Information System data from 2018-2024, including 421,877 EMS encounters across eight rural counties, with 242,029 cases occurring in border counties, and 179,848 cases occurred in comparison counties. We compared the patterns of primary payer, number of patients at the scene, mass casualty incident, trauma triage criteria, and delays of EMS encounters. These variables were summarized using frequencies and percentages and compared between border and non-border counties using chi-square tests. Given the large number of EMS encounters, absolute percentage point differences and Cramer's V were also reported to assess the magnitude of differences between the two groups.

We found that differences exist regarding payer types, injury types, and delay types, with varying effect sizes. Effect sizes for payer, high risk of serious injury, response delay and scene delay between border and comparison counties were moderate to large, while those for moderate risk of serious injury and transport delay were small to moderate. Regarding injury types, border counties had more cases of falls from 20 feet or more compared to non-border counties, as well as higher injuries that represent severe trauma or environmental exposure compared to non-border counties (25.5% vs. 8.2%).

These findings suggest that important differences exist between counties along the U.S.-Mexico border and comparison non-border counties because of their location along the international boundary, with implications for EMS performance.