The evolving prehospital care: a 12-year retrospective analysis.

Abstract

Background: Emergency medical services (EMS) are one of the main interfaces between acutely ill patients in the prehospital environment and hospital-based care. Yet longitudinal, population-level studies of EMS patient populations remain limited. We aimed to characterize temporal trends in EMS demand, triage acuity, hospital admission, and short-term mortality among patients managed by EMS and transported to emergency departments (EDs) in a Swedish healthcare system from 2011 to 2022.

Methods: This was a retrospective, population-based study of all primary EMS assignments in Region Östergötland, Sweden (catchment population 456,000), from 2011 to 2022. Data were extracted from linked electronic health records encompassing EMS, ED, and inpatient care. Triage acuity was classified using the Rapid Emergency Triage and Treatment System (RETTS). The primary outcome was the temporal trend in triage acuity among EMS patients. Secondary outcomes included hospital admission rates, 1, 7, 30, and 90-day mortality, and non-transport disposition rates. Proportional-odds ordinal regression and multivariable logistic regression were used to assess temporal trends. Descriptive statistics were used to summarize demographic data.

Results: Of 474,647 included primary assignments, 394,580 (83.1%) resulted in ED transport. Triage acuity shifted progressively toward higher-severity categories. The combined proportion of acuity levels 1 and 2 (highest) increased from 32% to 57%, with an 8% annual increase in odds of higher classification (OR 1.08 per year, 95% CI 1.08-1.09). Non-transport dispositions rose from 5% to 25% of primary assignments. The hospital admission rate among EMS-transported patients was constant at approximately 50%, but their share of all ED-originating hospital admissions increased from 42% to 57%. Short-term mortality was stable; triage acuity was the strongest predictor of death at all time points (OR 1.14-5.15 per level).

Conclusions: Over 12 years, EMS-transported patients presented with progressively higher triage acuity while constituting an increasing share of hospital admissions. These trends, concurrent with a fivefold expansion in non-transport dispositions, reflect a shift in the role of EMS toward field-based clinical assessment and disposition. These findings have implications for EMS resource planning, triage system evaluation, and the integration of prehospital data into hospital capacity management.