Association between EMS Workforce Density and Population Health Outcomes in the U.S.

Background: The prehospital care provided by emergency medical services (EMS) personnel is a critical component of the public health, public safety, and health care systems in the U.S.; however, the population-level value of EMS care is often overlooked. No studies have examined how the density of EMS personnel relates to population-level health outcomes. Our objectives were to examine the geographic distribution and density of EMS personnel in the U.S.; and quantify the association between EMS personnel density and population-level health outcomes.

Methods: We conducted a cross-sectional evaluation of county-level EMS personnel density using estimates from the National Registry of Emergency Medical Technicians in nine states that require continuous national certification (Alabama, Louisiana, Massachusetts, Minnesota, New Hampshire, North Dakota, South Carolina, Vermont, and Washington, D.C.). Outcomes of interest included life expectancy, all-cause mortality, and cardiac arrest mortality. We used quantile regression models to examine the association between a 10-person increase in EMS personnel density and each outcome at the 10, 50 (median), and 90 percentiles, controlling for population characteristics and area health resources.

Results: There were 356 counties included, with a mean EMS density of 223 EMS personnel per 100,000 population. Density was higher in rural compared to urban counties (247 versus 186 per 100,000 population; p = 0.001). In unadjusted models, there was a significant association between increase in EMS personnel density and an increase in life expectancy at each examined percentile (e.g., 50 percentile, increase of 52.9 days; 95% CI 40.2, 65.5; p < 0.001), decrease in all-cause mortality at each examined percentile, and decrease in cardiac arrest mortality at the 50 and 90 percentiles. These associations were not statistically significant in the adjusted models.

Conclusions: EMS personnel density differs between urban and rural areas, with higher density per population in rural areas. There were no statistically significant associations between EMS density and population-level health outcomes after controlling for population characteristics and other health resources. The best approach to quantifying the community-level value that EMS care may or may not provide remains unclear.