Characterizing the performance of emergency medical transport time metrics in a residentially segregated community

This article was originally published here

Am J Emerg Med. 2021 Jul 9;50:111-119. doi: 10.1016/j.ajem.2021.07.013. Online ahead of print.


OBJECTIVE: To derive and characterize the performance of various metrics of emergency transport time in assessing for sociodemographic disparities in the setting of residential segregation. Secondarily to characterize racial disparities in emergency transport time of suspected stroke patients in Austin, Texas.

DATA SOURCES: We used a novel dataset of 2518 unique entries with detailed spatial and temporal information on all suspected stroke transports conducted by a public emergency medical service in Central Texas between 2010 and 2018.

STUDY DESIGN: We conducted one-way ANOVA tests with post-hoc pairwise t-tests to assess how mean hospital transport times varied by patient race. We also developed a spatially-independent metric of emergency transport urgency, the ratio of expected duration of self-transport to a hospital and the measured transport time by an ambulance.

DATA COLLECTION/EXTRACTION: We calculated ambulance arrival and destination times using sequential temporospatial coordinates. We excluded any entries in which patient race was not recorded. We also excluded entries in which ambulances’ routes did not pass within 100 m of either the patient’s location or the documented hospital destination.

PRINCIPAL FINDINGS: We found that mean transport time to a hospital was 2.5 min shorter for black patients compared to white patients. However, white patients’ transport times to a hospital were found to be, on average, 4.1 min shorter than expected compared to 3.4 min shorter than expected for black patients. One-way ANOVA testing for the spatially-independent index of emergency transport urgency was not statistically significant, indicating that average transport time did not vary significantly across racial groups when accounting for variations in transport distance.

CONCLUSIONS: Using a novel transport urgency index, we demonstrate that these findings represent race-based variation in spatial distributions rather than racial bias in emergency medical transport. These results highlight the importance of closely examining spatial distributions when utilizing temporospatial data to investigate geographically-dependent research questions.

PMID:34340164 | DOI:10.1016/j.ajem.2021.07.013