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Accuracy of emergency medical dispatchers’ subjective ability to identify when higher dispatch levels are warranted over a Medical Priority Dispatch System automated protocol’s recommended coding based on paramedic outcome data
  1. Jeff Clawson1,
  2. Christopher H O Olola1,
  3. Andy Heward2,
  4. Greg Scott1,
  5. Brett Patterson3
  1. 1International Academies of Emergency Dispatch, Salt Lake City, Utah, USA
  2. 2London Ambulance Service NHS Trust, London, UK
  3. 3International Academies of Emergency Dispatch (IAED), Florida, USA
  1. Correspondence to:
 Jeff Clawson
 MD, International Academies of Emergency Dispatch, 139 East South Temple, Suite 200, Salt Lake City, Utah 84111, USA; jeff.clawson{at}


Objectives: To establish the accuracy of the emergency medical dispatcher’s (EMD’s) decisions to override the automated Medical Priority Dispatch System (MPDS) logic-based response code recommendations based on at-scene paramedic-applied transport acuity determinations (blue-in) and cardiac arrest (CA) findings.

Methods: A retrospective study of a 1 year dataset from the London Ambulance Service (LAS) National Health Service (NHS) Trust was undertaken. We compared all LAS “bluing in” frequency (BIQ) and cardiac arrest quotient (CAQ) outcomes of the incidents automatically recommended and accepted as CHARLIE-level codes, to those receiving EMD DELTA-overrides from the auto-recommended CHARLIE-level. We also compared the recommended DELTA-level outcomes to those in the higher ECHO-override cases.

Results: There was no significant association between outcome (CA/Blue-in) and the determinant codes (DELTA-override and CHARLIE-level) for both CA (odds ratio (OR) 0, 95% confidence interval (CI) 0 to 41.14; p = 1.000) and Blue-in categories (OR 0.89, 95% CI 0.34 to 2.33; p = 1.000). Similar patterns were observed between outcome and all DELTA-level and ECHO-override codes for both CA (OR 0, 95% CI 0 to 70.05; p = 1.000) and Blue-in categories (OR 1.17, 95% CI 0 to 7.12; p = 0.597).

Conclusion: This study contradicts the belief that EMDs can accurately perceive when a patient or situation requires more resources than the MPDS’s structured interrogation process logically indicates. This further strengthens the concept that automated, protocol-based call taking is more accurate and consistent than the subjective, anecdotal or experience-based determinations made by individual EMDs.

  • BIQ, “bluing in” percentage quotient
  • CA, cardiac arrest
  • CAQ, cardiac arrest percentage quotient
  • EMD, emergency medical dispatcher
  • IAED, International Academies of Emergency Dispatch
  • LAS, London Ambulance Service
  • MPDS, Medical Priority Dispatch System
  • NHS, National Health Service

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  • Source of support: No specific funding was provided outside of the employment relationships noted in the competing interests section below.

  • Conflict of interest: JC is CEO and Medical Director of the Research and Standards Division of Priority Dispatch Corp. and member of the Council of Standards, Board of Certification, and Board of Trustees of the International Academies of Emergency Dispatch. He is the inventor of the Medical Priority Dispatch Protocol and Quality Assurance System studied herein. BP is Academics and Standards Editor for the IAED and Chair of the IAED Council of Research. CO is a medical informatics researcher and statistical expert employed part-time by the IAED for study development and validation only. AH is the Priority Dispatch Development Officer for the London Ambulance Service NHS Trust and the Emergency Call Management Advisor with lead on Call Categorisation at the Department of Health, UK. GS is a Medical Protocol and Quality Assurance Consultant, Priority Dispatch Corporation.

  • Ethical approval: Not required. All the data were gleaned from a specific 999 call aggregate database not containing any patient identifying information.

    Contributors: AH de-identified, aggregated and provided the initial one-year 999 call and outcome database. JC conceived the study idea, formulated the initial study plan and protocol. JC, AH, BP, GS, and CO drafted the manuscript, which was revised based on the comments of all authors. CO provided the statistical structure and validation of the data.