title: The comparability of emergency department waiting time performance data.
abstract: OBJECTIVE
  To examine whether the reported urgency mix of an emergency department's (ED's) patients is associated with its waiting time performance.
  
  
  METHODS
  Cross-sectional analysis of data on patient urgency mix and hospital ED performance reported on the MyHospitals website for July 2009 - June 2010.
  
  
  METHODS
  ED performance assessed as the proportion of patients whose care was initiated within the recommended time frame for each of four triage categories.
  
  
  RESULTS
  Data for 158 hospitals showed that EDs with a higher proportion of patients assigned to the emergency category have poorer waiting time performance, after adjusting for hospital characteristics. Conversely, EDs with a higher proportion of patients assigned to the non-urgent category perform better. If performance scores were adjusted for reported patient urgency mix and hospital peer group, mean adjustments would be modest in size (3.7-7.1 percentage points, depending on the category), but for individual EDs the differences could be large (as large as 31 percentage points) and hospital waiting time performance rankings would be substantively impacted.
  
  
  CONCLUSIONS
  Since ED performance is related to reported patient urgency mix, adjusting for casemix in the ED may be warranted to ensure valid comparisons between hospitals. Further investigation of the validity of performance measures and appropriate adjustment for differences in hospital and patient characteristics is required if public reporting is to meet its goals.
authors.affiliation: Planning, Public Policy and Management, University of Oregon, Eugene, OR, USA. jessicag@uoregon.edu
authors.forename: Jessica
authors.initials: J
authors.lastname: Greene
authors.forename: Jane
authors.initials: J
authors.lastname: Hall
mesh_terms: D001315:Australia; D003430:Cross-Sectional Studies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D006761:Hospitals; D006801:Humans; D011787:Quality of Health Care; D013997:Time Factors; D014218:Triage; D014850:Waiting Lists