title: The changing profile of patients who used emergency department services in the United States: 1996 to 2005.
abstract: OBJECTIVE
  Because of the vital role of emergency departments (EDs) in the US health care system, it is important to monitor the changes in the patient mix over time to identify existing problems and ways to improve the system. The current study aimed to identify raw and population-adjusted time trends for demographic characteristics, socioeconomic characteristics, access to care, utilization of care, and general health of ED users and heavy ED users.
  
  
  METHODS
  Ten years' worth of nationally representative data was derived from the Medical Expenditure Panel Survey, 1996 to 2005. Raw time trends of various patient characteristics for ED users, nonusers, and heavy users were estimated to demonstrate changes in ED patient mix. Population-attributable fraction was used to generate population-adjusted trends that elucidate the net changes in subpopulations' propensities to ED use in relation to those of the general population.
  
  
  RESULTS
  Between 1996 and 2005, the total number of noninstitutionalized individuals who used ED services increased from 34.2 to 40.8 million. That is, the proportion of ED users in the US population increased from 12.7% to 13.8%. Increasing proportions of elderly and those who perceived themselves to be in poor or fair physical health among ED users, particularly heavy users, were found in both raw and population-adjusted trends. Several subpopulations demonstrated increasing levels of ED use after population adjustment: blacks, patients within 100% to 199% of the federal poverty line, patients with only Medicare, patients with greater than or equal to 2 types of insurance, and patients with at least 1 inpatient stay. Decreasing population-adjusted trends were found in the proportions of female patients, Hispanics, patients at greater than or equal to 200% of the federal poverty line, the uninsured, and patients with only private insurance, respectively.
  
  
  CONCLUSIONS
  EDs play a larger role in the management of geriatric patients over time. The increasing burden of the aging population in the EDs poses challenges in the training of future emergency physicians, care for older patients, public health insurance, and health care system reform.
authors.affiliation: Department of Family and Community Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430-8143, USA. tom.xu@ttuhsc.edu
authors.forename: K Tom
authors.initials: KT
authors.lastname: Xu
authors.forename: Brian K
authors.initials: BK
authors.lastname: Nelson
authors.forename: Steven
authors.initials: S
authors.lastname: Berk
mesh_terms: D017677:Age Distribution; D000368:Aged; D003953:Diagnosis-Related Groups; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006297:Health Services Accessibility; D006301:Health Services Needs and Demand / Q000639:trends*; D006299:Health Services for the Aged; D006304:Health Status; D006801:Humans; D008297:Male; D012959:Socioeconomic Factors; D014481:United States