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Response Time Effectiveness:Comparison of Response Time and Survival in an Urban Emergency Medical Services System

  1. Thomas H. Blackwell MD1,2,4,*,
  2. Jay S. Kaufman PhD3

Article first published online: 28 JUN 2008

DOI: 10.1197/aemj.9.4.288

Issue

Academic Emergency Medicine

Academic Emergency Medicine

Volume 9, Issue 4, pages 288–295, April 2002

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How to Cite

Blackwell, T. H. and Kaufman, J. S. (2002), Response Time Effectiveness:Comparison of Response Time and Survival in an Urban Emergency Medical Services System. Academic Emergency Medicine, 9: 288–295. doi: 10.1197/aemj.9.4.288

Author Information

  1. 1

    Center for Prehospital Medicine (THB), Charlotte, NC. Dr. Kaufman is currently in the Department of Epidemiology, UNC School of Public Health, Chapel Hill, NC.

  2. 2

    Departments of Emergency Medicine (THB) Charlotte, NC. Dr. Kaufman is currently in the Department of Epidemiology, UNC School of Public Health, Chapel Hill, NC.

  3. 3

    Departments of Epidemiology (JSK)and Departments of Statistics Charlotte, NC. Dr. Kaufman is currently in the Department of Epidemiology, UNC School of Public Health, Chapel Hill, NC.

  4. 4

    Departments of Carolinas Medical Center, and Mecklenburg EMS Agency (THB) Charlotte, NC. Dr. Kaufman is currently in the Department of Epidemiology, UNC School of Public Health, Chapel Hill, NC.

*Department of Emergency Medicine, Carolinas Medical Center, P.O. Box 32861, Charlotte, NC 28232-2861. Fax: 704-355-7047; e-mail: tom.blackwell@carolinashealthcare.org

Publication History

  1. Issue published online: 28 JUN 2008
  2. Article first published online: 28 JUN 2008
  3. Received June 1, 2001; revision August 27, 2001; revision November 6, 2001; accepted November 15, 2001

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Keywords:

  • prehospital;
  • emergency medical services;
  • response time;
  • effectiveness;
  • standards

Abstract. Emergency medical services (EMS) administrators seek methods to enhance system performance. One component scrutinized is the response time (RT) interval between call receipt and arrival on scene. While reducing RTs may improve survival, this remains speculative and unreported.

Objective: To determine the effect of current RTs on survival in an urban EMS system.

Methods: The study was conducted in a metropolitan county (population 620,000). The EMS system is a single-tier, paramedic service and provides all service requests. The 90% fractile RT specifications required for county compliance include 10:59 minutes for emergency life-threatening calls (priority I) and 12:59 minutes for emergency non-life-threatening calls (priority II). All emergency responses resulting in a priority I or priority II transport to a Level 1 trauma center emergency department over a six-month period were evaluated to determine the relation between specified and arbitrarily assigned RTs and survival.

Results: Five thousand, four hundred twenty-four transports were reviewed. Of these, 71 patients did not survive (1.31%; 95% CI = 1.04% to 1.67%). No significant difference in median RTs between survivors (6.4 min) and nonsurvivors (6.8 min) was noted (p = 0.10). Further, there was no significant difference between observed and expected deaths (p = 0.14). However, mortality risk was 1.58% for patients whose RT exceeded 5 minutes, and 0.51% for those whose RT was under 5 minutes (p = 0.002). The mortality risk curve was generally flat over RT intervals exceeding 5 minutes.

Conclusions: In this observational study, emergency calls where RTs were less than 5 minutes were associated with improved survival when compared with calls where RTs exceeded 5 minutes. While variables other than time may be associated with this improved survival, there is little evidence in these data to suggest that changing this system's response time specifications to times less than current, but greater than 5 minutes, would have any beneficial effect on survival.

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