Prehospital Time Disparities for Rural Patients with Suspected STEMI

Abstract

Background

Rural patients with ST-elevation myocardial infarction (STEMI) may be less likely to receive prompt reperfusion therapy. This study’s primary objective was to compare rural versus urban time intervals among a national cohort of prehospital patients with STEMI.

Methods

The ESO Data Collaborative (Austin, TX), containing records from 1,366 emergency medical services agencies, was queried for adult 9-1-1 responses with suspected STEMI from 1/1/2018-12/31/2019. The scene address for each encounter was classified as either urban or rural using the 2010 US Census Urban Area Zip Code Tabulation Area relationship. The primary outcome was total EMS interval (9-1-1 call to hospital arrival); a key secondary outcome was the proportion of responses that had EMS intervals under 60 minutes. Generalized estimating equations were used to determine whether rural versus urban differences in interval outcomes occurred when adjusting for loaded mileage (distance from scene to hospital) and patient and clinical encounter characteristics.

Results

Of 15,915,027 adult 9-1-1 transports, 23,655 records with suspected STEMI were included in the analysis. Most responses (91.6%, n = 21,661) occurred in urban settings. Median EMS interval was 37.6 minutes (IQR 30.0-48.0) in urban settings compared to 57.0 minutes (IQR 46.5-70.7) in rural settings (p < 0.01). Urban responses more frequently had EMS intervals <60 minutes (89.5%, n = 19,130), compared to rural responses (55.5%, n = 1,100, p < 0.01). After adjusting for loaded mileage, age, sex, race/ethnicity, abnormal vital signs, pain assessment, aspirin administration, and IV/IO attempt, rural location was associated with a 5.8 (95%CI 4.2-7.4) minute longer EMS interval than urban, and rural location was associated with a reduced chance of achieving EMS interval < 60 minutes (OR 0.40; 95%CI 0.33-0.49) as compared to urban location.

Conclusion

In this large national sample, rural location was associated with significantly longer EMS interval for patients with suspected STEMI, even after accounting for loaded mileage.

Author contribution statement

Jason P. Stopyra: Conceptualization, Methodology, Validation, Investigation, Visualization, Supervision, Project administration; Remle P. Crowe: Conceptualization, Methodology, Validation, Investigation, Visualization, Formal analysis, Data Curation; Anna C. Snavely: Conceptualization, Methodology, Validation, Investigation, Visualization, Formal analysis, Data Curation; Michael W. Supples: Conceptualization, Investigation, Visualization; Nathan Page: Conceptualization, Investigation, Visualization; Zachary Smith: Conceptualization, Investigation, Visualization; Nicklaus P. Ashburn: Conceptualization, Investigation, Visualization; Kristie Foley: Conceptualization, Investigation, Visualization; Chadwick D. Miller: Conceptualization, Methodology, Validation, Investigation, Visualization; Simon A. Mahler: Conceptualization, Methodology, Validation, Investigation, Visualization, Supervision, Project administration

Disclosure statement

Dr. Ashburn receives funding from NHLBI (T32HL076132). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. Dr. Snavely receives funding from Abbott Laboratories and HRSA (1H2ARH399760100). Dr. Stopyra receives research funding from NCATS/NIH (KL2TR001421), HRSA (H2ARH39976-01-00), Roche Diagnostics, Abbott Laboratories, Pathfast, Genetesis, Cytovale, Forest Devices, Vifor Pharma, and Chiesi Farmaceutici. Dr. Mahler receives funding/support from Roche Diagnostics, Abbott Laboratories, Ortho Clinical Diagnostics, Siemens, Grifols, Pathfast, Quidel, Genetesis, Cytovale, and HRSA (1H2ARH399760100). He is a consultant for Roche, Quidel, Genetesis, Inflammatix, Radiometer, and Amgen and the Chief Medical Officer for Impathiq Inc.