Urban sprawl and delayed ambulance arrival in the U.S.
BACKGROUND
Minimizing emergency medical service (EMS) response time is a central objective of prehospital care, yet the potential influence of built environment features such as urban sprawl on EMS system performance is often not considered.


OBJECTIVE
This study measures the association between urban sprawl and EMS response time to test the hypothesis that features of sprawling development increase the probability of delayed ambulance arrival.


METHODS
In 2008, EMS response times for 43,424 motor-vehicle crashes were obtained from the Fatal Analysis Reporting System, a national census of crashes involving > or =1 fatality. Sprawl at each crash location was measured using a continuous county-level index previously developed by Ewing et al. The association between sprawl and the probability of a delayed ambulance arrival (> or =8 minutes) was then measured using generalized linear mixed modeling to account for correlation among crashes from the same county.


RESULTS
Urban sprawl is significantly associated with increased EMS response time and a higher probability of delayed ambulance arrival (p=0.03). This probability increases quadratically as the severity of sprawl increases while controlling for nighttime crash occurrence, road conditions, and presence of construction. For example, in sprawling counties (e.g., Fayette County GA), the probability of a delayed ambulance arrival for daytime crashes in dry conditions without construction was 69% (95% CI=66%, 72%) compared with 31% (95% CI=28%, 35%) in counties with prominent smart-growth characteristics (e.g., Delaware County PA).


CONCLUSIONS
Urban sprawl is significantly associated with increased EMS response time and a higher probability of delayed ambulance arrival following motor-vehicle crashes in the U.S. The results of this study suggest that promotion of community design and development that follows smart-growth principles and regulates urban sprawl may improve EMS performance and reliability.
Trowbridge
Matthew J
MJ
Department of Emergency Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908-0699, USA. mtrowbridge@virginia.edu
Gurka
Matthew J
MJ
O'Connor
Robert E
RE
D000063:Accidents, Traffic / Q000706:statistics & numerical data; D000552:Ambulances; D016208:Databases, Factual; D004632:Emergency Medical Services / Q000592:standards* / Q000706:statistics & numerical data; D006801:Humans; D016014:Linear Models; D013997:Time Factors; D014481:United States; D019037:Urban Health Services / Q000592:standards* / Q000706:statistics & numerical data; D014506:Urban Renewal