title: Emergency department volume and racial and ethnic differences in waiting times in the United States.
abstract: BACKGROUND
  Racial and ethnic differences in emergency department (ED) waiting times have been observed previously.
  
  
  OBJECTIVE
  We explored how adjusting for ED attributes, particularly visit volume, affected racial/ethnic differences in waiting time.
  
  
  METHODS
  We constructed linear models using generalized estimating equations with 2007-2008 National Hospital Ambulatory Medical Care Survey data.
  
  
  METHODS
  We analyzed data from 54,819 visits to 431 US EDs.
  
  
  METHODS
  Our dependent variable was waiting time, measured from arrival to time seen by physician, and was log transformed because it was skewed. Primary independent variables were individual race/ethnicity (Hispanic and non-Hispanic white, black, other) and ED race/ethnicity composition (covariates for percentages of Hispanics, blacks, and others). Covariates included patient age, triage assessment, arrival by ambulance, payment source, volume, region, and teaching hospital.
  
  
  RESULTS
  Geometric mean waiting times were 27.3, 37.7, and 32.7 minutes for visits by white, black, and Hispanic patients. Patients waited significantly longer at EDs serving higher percentages of black patients; per 25 point increase in percent black patients served, waiting times increased by 23% (unadjusted) and 13% (adjusted). Within EDs, black patients waited 9% (unadjusted) and 4% (adjusted) longer than whites. The ED attribute most strongly associated with waiting times was visit volume. Waiting times were about half as long at low-volume compared with high-volume EDs (P<0.001). For Hispanic patients, differences were smaller and less robust to model choice.
  
  
  CONCLUSIONS
  Non-Hispanic black patients wait longer for ED care than whites primarily because of where they receive that care. ED volume may explain some across-ED differences.
authors.affiliation: Division of Health Care Statistics, National Center for Health Statistics, Hyattsville, MD, USA. nancy.sonnenfeld@cms.hhs.go
authors.forename: Nancy
authors.initials: N
authors.lastname: Sonnenfeld
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Pitts
authors.forename: Susan M
authors.initials: SM
authors.lastname: Schappert
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Decker
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D044383:Black People / Q000706:statistics & numerical data; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005006:Ethnicity / Q000706:statistics & numerical data*; D005260:Female; D019538:Health Care Surveys; D054625:Healthcare Disparities / Q000706:statistics & numerical data*; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D044469:Racial Groups / Q000706:statistics & numerical data*; D014481:United States; D014850:Waiting Lists; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult; D001741:Black or African American