title: Identifying patients with cellulitis who are likely to require inpatient admission after a stay in an ED observation unit.
abstract: BACKGROUND
  Emergency department observation units (EDOU) are often used for patients with cellulitis to provide intravenous antibiotics followed by a transition to an oral regimen for discharge. Because institutional regulations typically limit EDOU stays to 24 hours, patients lacking a clinical response within this period will often be subsequently admitted to the hospital for further treatment.
  
  
  OBJECTIVE
  The aim of this study was to determine the rate of hospital admission and characteristics predictive of admission in patients with cellulitis who are initially placed in an ED observation unit.
  
  
  METHODS
  A retrospective cohort study of patients placed into EDOU with a diagnosis of skin infection was conducted. Age, sex, history of diabetes mellitus, immunosuppression, intravenous drug use, location of cellulitis, presence of abscess, laboratory infectious markers, vital signs, and outpatient antibiotic treatment were recorded. The primary outcome was a hospital admission due to failure to respond to treatment within the 24-hour observation time window. Significant variables on univariate analysis were used to create a multivariate analysis, which identified predictive characteristics.
  
  
  RESULTS
  Four hundred six patient charts were reviewed, with 377 meeting inclusion criteria; the inpatient admission rate from EDOU was 29.2%. Using logistic regression techniques, we created a model of independent predictors for need of admission after 24 hours: cellulitis of the hand (odds ratio [OR], 2.9; 95% confidence interval [CI], 1.8-4.9), measured temperature higher than 100.4°F (OR, 2.5; 95% CI, 1.1-5.5), and lactate greater than 2 (OR, 3.1; 95% CI, 1.3-7.3) were predictive of failure of ED observation.
  
  
  CONCLUSIONS
  Patients with cellulitis placed into ED observation status were more likely to fail an observation trial if they had an objective fever in the ED, an elevated lactate, or a cellulitis that involved the hand.
authors.affiliation: Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA. kvolz@bidmc.harvard.edu
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Volz
authors.forename: Louisa
authors.initials: L
authors.lastname: Canham
authors.forename: Emily
authors.initials: E
authors.lastname: Kaplan
authors.forename: Leon D
authors.initials: LD
authors.lastname: Sanchez
authors.forename: Nathan I
authors.initials: NI
authors.lastname: Shapiro
authors.forename: Shamai A
authors.initials: SA
authors.lastname: Grossman
mesh_terms: D061605:Administration, Intravenous; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002481:Cellulitis / Q000175:diagnosis / Q000188:drug therapy*; D015331:Cohort Studies; D004636:Emergency Service, Hospital / Q000458:organization & administration*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010343:Patient Admission / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D017211:Treatment Failure
chemical_list: D000900:Anti-Bacterial Agents