title: Monitoring patient flow in emergency departments: the use of scatterplots versus time-based measures to assess patient flow in A&E.
abstract: OBJECTIVE
  Care providers need accurate information to help them effectively manage patient flow in emergency departments (EDs) and deliver high-quality care within time constraints. Data should alert care providers to clinical risk and poor patient experience. In England, NHS A&E guidance proposes, among others, three measures to understand the distribution of waiting times in EDs - the median wait, 95th percentile and maximum wait. This study explores how well these three measures monitor performance and the potential added value of scatterplots.
  
  
  METHODS
  Anonymized patient-level data on 463 000 patient visits collected over 2 full years recording length of stay to the nearest minute from four separate EDs were analysed. Scatterplots providing a detailed representation of the distribution of waiting times were produced for all sites. For each hospital, we explored how informative the scatterplots were compared with the single measures required under the NHS Outcomes Framework.
  
  
  RESULTS
  There are several instances where the use of scatterplots adds value by identifying concerns that are not detected by the use of single measures alone.
  
  
  CONCLUSIONS
  The use of scatterplots could help care providers better understand the distribution of waiting times in EDs, identify where EDs struggle to deliver care against time constraints and highlight poor patient experience and prompt action to address concerns.
authors.affiliation: aNIHR CLAHRC for Northwest London, Chelsea and Westminster Hospital, London bDepartment of Acute Medicine, Royal Infirmary of Edinburgh, Edinburgh, UK.
authors.forename: Cathal
authors.initials: C
authors.lastname: Doyle
authors.forename: Mike
authors.initials: M
authors.lastname: Jones
authors.forename: Derek
authors.initials: D
authors.lastname: Bell
mesh_terms: D003627:Data Interpretation, Statistical; D004636:Emergency Service, Hospital / Q000458:organization & administration / Q000592:standards / Q000706:statistics & numerical data*; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D013997:Time Factors; D014850:Waiting Lists