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Unnecessary wait hours: a novel ED system-level metric
  1. Heather A Heaton1,
  2. David M Nestler1,
  3. Kalyan S Pasupathy2,
  4. Phichet Wutthisirisart2,
  5. Mustafa Y Sir2,
  6. Thomas R Hellmich1
  1. 1 Department of Emergency Medicine, Mayo Clinic, Rochester, Minnesota, USA
  2. 2 Mayo Clinic Department of Health Sciences Research, Rochester, Minnesota, USA
  1. Correspondence to Dr Heather A Heaton, Department of Emergency Medicine, Mayo Clinic, Rochester, MN 55906, USA; heaton.heather{at}


Background Emergency department (ED) operations leaders are under increasing pressure to make care delivery more efficient. Publicly reported ED efficiency metrics are traditionally patient centred and do not show situational or facility-based improvement opportunities. We propose the consideration of a novel metric, the ‘Number of Unnecessary Waits (NUW)’ and the corresponding ‘Unnecessary Wait Hours (UWH)’, to measure space efficiency, and we describe how we used NUW to evaluate operational changes in our ED.

Methods UWH summarises the relationship between the number of available rooms and the number of patients waiting by returning a value equal to the number of unnecessary patient waits. We used this metric to evaluate reassigning a clinical technician assistant (CTA) to the new role of flow CTA.

Results We retrospectively analysed 3.5 months of data from before and after creation of the flow CTA. NUW metric analysis suggested that the flow CTA decreased the amount of unnecessary wait hours, while higher patient volumes had the opposite effect.

Conclusions Situational system-level metrics may provide a new dimension to evaluating ED operational efficiencies. Studies focussed on system-level metrics to evaluate an ED practice are needed to understand the role these metrics play in evaluation of a department’s operations.

  • emergency department

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  • Handling editor Edward Carlton

  • Contributors All were involved with study concept and design; HAH, DMN, KSP, PW, MYS participated in acquisition of the data; All participated in analysis and interpretation of the data; KSP, PW, MYS did the statistical analysis; HAH, DMN, TRH were involved in the initial draft of the manuscript; All participated in critical revision of the manuscript.

  • Funding This study was supported by funds from the Mayo Clinic Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery and contributions from the Mayo Clinic Emergency Department–Clinical Engineering Learning Laboratory.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.