Ambulance deserts and inequities in access to emergency medical services care: Are injured patients at risk for delayed care in the prehospital system?

INTRODUCTION Delayed Emergency Medical Services (EMS) response and transport (time from injury occurrence to hospital arrival) are associated with increased injury mortality. Inequities in accessing EMS care for injured patients are not well characterized. We sought to evaluate the association between the area deprivation index (ADI), a measure of geographic socioeconomic disadvantage, and timely access to EMS care within the United States. METHODS The Homeland Infrastructure Foundation Level Data open-source database from the National Geospatial Intelligence Agency was used to evaluate the location of EMS stations across the United States using longitude and latitude coordinates. The ADI was obtained from Neighborhood Atlas at the census block group level. An ambulance desert (AD) was defined as populated census block groups with a geographic center outside of a 25-minute ambulance service area. The total population (urban and rural) located within an AD and outside an AD (non-ambulance desert [NAD]) and the ADI index distribution within those areas were calculated with their statistical significance derived from χ² testing. Spearman correlations between the number of EMS stations available within 25-minutes service areas and ADI were calculated, and statistical significance was derived after accounting for spatial autocorrelation. RESULTS A total of 42,472 ground EMS stations were identified. Of the 333,036,755 people (current US population), 2.6% are located within an AD. When stratified by type of population, 0.3% of people within urban populations and 8.9% of people within rural populations were located within an AD (p < 0.01). When compared with NADs, ADs were more likely to have a higher ADI (ADI_AD, 53.13; ADI_NAD, 50.41; p < 0.01). The number of EMS stations available per capita was negatively correlated with ADI (r_s = -0.25, p < 0.01), indicating that people living in more disadvantaged neighborhoods are likely to have fewer EMS stations available. CONCLUSION Ambulance deserts are more likely to affect rural versus urban populations and are associated with higher ADIs. The impact of inequities in access to EMS care on outcomes deserves further study.