Volume versus outcome: More emergency medical services personnel on-scene and increased survival after out-of-hospital cardiac arrest.
OBJECTIVE
The large regional variation in survival after treatment of out-of-hospital cardiac arrest (OHCA) is incompletely explained. Communities respond to OHCA with differing number of emergency medical services (EMS) personnel who respond to the scene. The effect of different numbers of EMS personnel on-scene upon outcomes is unclear. We sought to evaluate the association between number of EMS personnel on-scene and survival after OHCA.


METHODS
We performed a retrospective review of prospectively collected data on 16,122 EMS-treated OHCA events from December 1, 2005 to May 31, 2007 from a combined population over 21 million people residing in an area of over 33,000 square miles in Canada and the United States. Number of EMS personnel on-scene was defined as the number of EMS personnel who responded to the scene of OHCA within 15 min after 9-1-1 call receipt and prior to patient death or transport away from the scene. Associations with survival to hospital discharge were assessed by using generalized estimating equations to construct multivariable logistic regression models.


RESULTS
Compared to a reference number of EMS personnel on-scene of 5 or 6, 7 or 8 EMS personnel on-scene was associated with a higher rate of survival to hospital discharge, adjusted odds ratio [OR], 1.35 (95% CI: 1.05, 1.73). There was no significant difference in survival between 5 or 6 personnel on-scene versus fewer.


CONCLUSIONS
More EMS personnel on-scene within 15 min of 9-1-1 call was associated with improved survival of out-of-hospital cardiac arrest. It is unlikely that this finding was mediated solely by earlier CPR or earlier defibrillation.
University of Washington, Harborview Center for Prehospital Emergency Care, Seattle, WA, United States; University of Washington, Department of Medicine, Seattle, WA, United States. Electronic address: sawarren@uw.edu.
Sam A
SA
Warren
University of Washington, Department of Biostatistics, Seattle, WA, United States; University of Washington, Clinical Trial Center, Department of Biostatistics, Seattle, WA, United States.
David K
DK
Prince
University of Washington, Harborview Center for Prehospital Emergency Care, Seattle, WA, United States; University of Washington, Department of Medicine, Seattle, WA, United States.
Ella
E
Huszti
University of Washington, Department of Medicine, Seattle, WA, United States.
Tom D
TD
Rea
University of Washington, Department of Epidemiology, Seattle, WA, United States; University of Washington, Collaborative Health Studies Coordinating Center, Seattle, WA, United States; University of Washington, Department of Global Health, Seattle, WA, United States.
Annette L
AL
Fitzpatrick
Emergency and Health Services Commission, British Columbia, Canada.
Douglas L
DL
Andrusiek
York Regional Emergency Medical Services, Sharon, Ontario, Canada.
Steve
S
Darling
Rescu, Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
Laurie J
LJ
Morrison
University of California San Diego Health System, United States.
Gary M
GM
Vilke
University of Washington, Harborview Center for Prehospital Emergency Care, Seattle, WA, United States; University of Washington, Department of Medicine, Seattle, WA, United States; University of Washington, Clinical Trial Center, Department of Biostatistics, Seattle, WA, United States.
Graham
G
Nichol
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002170:Canada / Q000453:epidemiology; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004632:Emergency Medical Services; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000628:therapy*; D010351:Patient Discharge / Q000639:trends; D058996:Quality Improvement; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D000078329:Workforce; D055815:Young Adult
Arrhythmia; Cardiopulmonary resuscitation; Heart arrest; Pharmacology