title: Predictors of hospital admission after ED observation unit care.
abstract: BACKGROUND
  Emergency department observation units (EDOUs) represent an opportunity to efficiently manage patients with common conditions requiring short-term hospital care. Understanding which patients are ultimately admitted to the hospital after care in an EDOU may enhance patient selection for EDOU care.
  
  
  METHODS
  We conducted a retrospective analysis of US emergency department visits resulting in admission to observation status using the National Hospital Ambulatory Care Survey (NHAMCS) from 2009 to 2010, a nationally representative sample. We used survey-weighted logistic regression to identify predictors at the patient level, visit level, and hospital level for inpatient hospital admission after EDOU care.
  
  
  RESULTS
  Between 2009 and 2010, there were 4.65 million patient visits (95% confidence interval [CI], 3.68-5.63) to EDOUs in the United States. Of those evaluated in an EDOU, 40.4% (95% CI, 34.5%-46.6%) were admitted to the hospital after EDOU care. Progressively older patient age was a strong predictor of hospital admission: patients age older than 65 years were more than 5 times more likely to be admitted than patients age younger than 18 years (odds ratio, 5.36; 95% CI, 2.26-12.73). The only other visit-level factor associated with admission was a reason for visit of chest pain; this was associated with a lower rate of hospital admission (odds ratio, 0.61; 95% CI, 0.41-0.91).
  
  
  CONCLUSIONS
  Across the United States in 2009 to 2010, older patient age was a strong predictor of admission after EDOU care, suggesting that older patients are more likely to require inpatient hospital services after EDOU care than younger patients.
authors.affiliation: Department of Emergency Medicine, Warren Alpert Medical School of Brown University, Providence, RI 02903. Electronic address: anapoli@lifespan.org.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Napoli
authors.affiliation: School of Continuing and Professional Studies, University of Virginia, 104 Midmont Lane, Charlottesville, VA 22904.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Mullins
authors.affiliation: Office for Clinical Practice Innovation, Washington, DC; Departments of Emergency Medicine and Health Policy, George Washington School of Medicine and Health Sciences, 2030 M St NW Room 4044, Washington, DC 20037.
authors.forename: Jesse M
authors.initials: JM
authors.lastname: Pines
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D019538:Health Care Surveys; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data*; D014481:United States