Factors Influencing Low-Acuity Emergency Medical Services Use: An Observational Study Guided by the Andersen Behavioral Model

ObjectivesEmergency Medical Services (EMS) demand is increasing, with a growing proportion of low-acuity encounters. Prior studies are limited by regional sampling, inconsistent definitions, narrow observation periods, and limited theoretical grounding. The objective of this study was to identify predisposing, enabling, and need-based factors associated with EMS transport among low-acuity emergency department (ED) patients, guided by Andersens Behavioral Model of Health Services Use. MethodsWe conducted a secondary, retrospective observational study using a 10% random sample of multicenter electronic health record (EHR) data from 21 emergency departments in the southeastern United States. To be eligible to be included in the analysis, the visit had to be for: (1) patient age >17 years of age, (2) occur between January 1, 2016, to April 29, 2025, (3) triaged as Emergency Severity Index (ESI) 4 or 5, and (4) ended in a final visit disposition of being discharged. The primary outcome was EMS utilization. Independent variables were categorized as predisposing, enabling, or need-based factors according to Andersens model. We used multivariable logistic regression to estimate adjusted odds ratios (aORs) with 95% confidence intervals. ResultsAmong 41,772 low-acuity ED encounters, 3,233 (7.7%) arrived by EMS. Increased odds of EMS use were associated with older age (per 10-year increase; aOR 1.30, 95% CI=1.27-1.33), male sex (aOR 1.20, 95% CI=1.12-1.30), being retired or disabled (aOR 3.60, 95% CI=3.15-4.10), being unemployed (aOR 2.26, 95% CI=2.04-2.52), having a nighttime presentation (aOR 1.63, 95% CI=1.51-1.76), and mental health diagnosis (aOR 1.76, 95% CI=1.62-1.90). Protective factors included White race (aOR=0.89, 95% CI=0.83-0.96), established primary care (aOR=0.57, 95% CI=0.57-0.62), weekend presentation (aOR 0.91; CI = 0.84-0.99), and visits during (aOR 0.63, 95% CI=0.55-0.71) or after (aOR 0.54, 95% CI=0.48-0.61) the COVID-19 period. Rurality, insurance, and primary language were not associated with EMS use. ConclusionsPredisposing and enabling factors were the predominant drivers of low-acuity EMS utilization in this sample. Expanding access to primary care and behavioral health services, especially for older patients, may reduce EMS use for low-acuity complaints while preserving EMS capacity for higher-acuity emergencies.