The association between EMS system characteristics and post-hospital discharge patient outcomes

Objective: Research in the field of EMS (emergency medical services) has been primarily limited to individual aspects of EMS systems and patient care. However, there is a need for a broad outcome-based analysis of the impacts of the overall system design. The aim of this study was to explore the associations between various EMS system design characteristics and patient outcomes post-hospital discharge. Methods: Data indicators were obtained according to the characteristics of 30 US EMS systems in large metropolitan areas, which account for 41.5% of the US population. Examples of indicators were the density of unit deployment, the use of ALS (advanced life support) first response, and the accreditation status of the dispatch center. Data were compared with local outcome/mortality data from national healthcare databases. Partial least squares structural equation modeling was used to identify relationships between the variables. Results: Of the nine latent variables studied, representing 29 individual indicators, local Medicare hospital rating scores (-.366 coefficient, p < 0.001, CI: -.485,-.134) and underlying socioeconomic and public health status (-.334, p < 0.001, CI: -.474, -.138) were the primary latent variables that showed practical significance (overall model R 2 = .736). Outcome measures described the relationship between the variables but cannot isolate EMS as the sole causal factor in outcomes. Conclusions: None of the EMS system-specific characteristics of the variables studied were associated with decreased patient mortality. The only two variables that showed a practically significant outcome were the indicators related to socioeconomic and public health data and the Medicare ratings of local hospitals.