title: Changes in the source of unscheduled hospitalizations in the United States.
abstract: BACKGROUND
  Hospitalizations represent a significant portion of the annual expenditures for the US health care system. Understanding recent changes in the sources of unscheduled admissions may provide opportunities to improve the quality and cost of inpatient care.
  
  
  OBJECTIVE
  To examine sources of unscheduled hospitalization over a 10-year period and implications for inpatient mortality and length of stay (LOS).
  
  
  METHODS
  Observational study using the 2000-2009 Nationwide Inpatient Sample.
  
  
  METHODS
  We categorized unscheduled hospitalizations as those related to transfers, direct admissions from outpatient providers, and the emergency department (ED).
  
  
  METHODS
  Hospitalization rates by source and clinical condition with multivariable regression analyses adjusted for patient demographics, comorbid conditions, and hospital factors to evaluate associated mortality and LOS outcomes.
  
  
  RESULTS
  Unscheduled hospitalizations arising from direct admissions and the ED changed substantially while those due to transfers remained relatively stable. The ED admitted 64.9% [95% confidence interval (CI), 62.8%-66.9%] of unscheduled hospitalizations in 2000, rising to 81.8% (95% CI, 80.5%-83.1%) by 2009, whereas direct admissions from outpatient providers correspondingly declined. In 2009, despite higher illness severity and chronic disease burden, hospitalization through the ED as compared with direct admissions was associated with an overall lower mortality adjusted odds ratio of 0.85 (95% CI, 0.77-0.93) and shorter adjusted hospital LOS of -0.84 (95% CI, -0.99 to -0.70) days.
  
  
  CONCLUSIONS
  Sources of unscheduled hospitalization in the United States have evolved, mostly resulting from care for a variety of clinical conditions now originating in the ED. This trend does not seem to be harming patients or worsening LOS.
authors.affiliation: Department of Emergency Medicine, University of Michigan, Ann Arbor, MI, USA. kkocher@umich.edu
authors.forename: Keith E
authors.initials: KE
authors.lastname: Kocher
authors.forename: Justin B
authors.initials: JB
authors.lastname: Dimick
authors.forename: Brahmajee K
authors.initials: BK
authors.lastname: Nallamothu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004636:Emergency Service, Hospital / Q000639:trends; D005260:Female; D017052:Hospital Mortality / Q000639:trends; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007902:Length of Stay / Q000639:trends; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data*; D012111:Residence Characteristics; D012621:Seasons; D012959:Socioeconomic Factors; D014481:United States; D055815:Young Adult