Prehospital and Disaster Medicine

Original Research

Disaster Metrics: A Proposed Quantitative Model for Benchmarking Prehospital Medical Response in Trauma-Related Multiple Casualty Events

Jamil D. Bayrama1 c1 and Shawki Zuabia2

a1 Department of Emergency Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, USA

a2 Department of Emergency Medicine, Orange Coast Memorial Medical Center, Orange County, California, USA


Introduction Quantitative benchmarking of trauma-related prehospital response for Multiple Casualty Events (MCE) is complicated by major difficulties due to the simultaneous occurrences of multiple prehospital activities.

Hypothesis/Problem Attempts to quantify the various components of prehospital medical response in MCE have fallen short of a comprehensive model. The objective of this study was to model the principal parameters necessary to quantitatively benchmark the prehospital medical response in trauma-related MCE.

Methods A two-step approach was adopted for the methodology of this study: an extensive literature search was performed, followed by prehospital system quantitative modeling. Studies on prehospital medical response to trauma injuries were used as the framework for the proposed model. The North Atlantic Treaty Organization (NATO) triage categories (T1-T4) were used for the study.

Results Two parameters, the Injury to Patient Contact Interval (IPCI) and Injury to Hospital Interval (IHI), were identified and proposed as the principal determinants of the medical prehospital response in trauma-related MCE. IHI is the time interval from the occurrence of injury to the completion of transfer of care of critical (T1) and moderate (T2) patients. The IHI for each casualty is compared to the Maximum Time Allowed described in the literature (golden hour for T1 and Friedrich's time for T2). In addition, the medical rescue factor (R) was identified as the overall indicator for the prehospital medical performance for T1 and T2, and a numerical value of one (R = 1) was proposed to be the quantitative benchmark.

Conclusion A new quantitative model for benchmarking prehospital response to MCE in trauma-related MCE is proposed. Prospective studies of this model are needed to validate its applicability.

Bayram J, Zuabi S. Disaster metrics: a proposed quantitative model for benchmarking prehospital medical response in trauma-related multiple casualty events. Prehosp Disaster Med. 2012;27(2):-7.

(Received February 11 2011)

(Accepted April 20 2011)

(Revised January 31 2012)

(Online publication May 17 2012)


c1 Correspondence: Jamil D. Bayram, MD, MPH EMDM, MEd Johns Hopkins School of Medicine 5801 Smith Avenue Davis Building, Suite 3220 Baltimore, Maryland 21209 USA E-mail


Conflict of interest: None