title: No specific time window distinguishes between community-, healthcare-, and hospital-acquired bacteremia, but they are prognostically robust.
abstract: OBJECTIVE
  We examined whether specific time windows after hospital admission reflected a sharp transition between community and hospital acquisition of bacteremia. We further examined whether different time windows to distinguish between community acquisition, healthcare association (HCA), and hospital acquisition influenced the results of prognostic models.
  
  
  METHODS
  Population-based cohort study.
  
  
  METHODS
  Hospitals in 3 areas of Denmark (2.3 million inhabitants) during 2000-2011.
  
  
  METHODS
  We computed graphs depicting proportions of males, absence of comorbidity, microorganisms, and 30-day mortality pertaining to bacteremia 0, 1, 2, …, 30, and 31 days and later after admission. Next, we assessed whether different admission (0-1, 0-2, 0-3, 0-7 days) and HCA (30, 90 days) time windows were associated with changes in odds ratio (OR) and area under the receiver operating characteristic (ROC) curve for 30-day mortality, adjusting for sex, age, comorbidity, and microorganisms.
  
  
  RESULTS
  For 56,606 bacteremic episodes, no sharp transitions were detected on a specific day after admission. Among the 8 combined time windows, ORs for 30-day mortality varied from 1.30 (95% confidence interval [CI], 1.23-1.37) to 1.99 (95% CI, 1.48-2.67) for HCA and from 1.36 (95% CI, 1.24-1.50) to 2.53 (95% CI, 2.01-3.20) for hospital acquisition compared with community acquisition. Area under the ROC curve changed marginally from 0.684 (95% CI, 0.679-0.689) to 0.700 (95% CI, 0.695-0.705).
  
  
  CONCLUSIONS
  No time transitions unanimously distinguished between community and hospital acquisition with regard to sex, comorbidity, or microorganisms, and no difference in 30-day mortality was seen for HCA patients in relation to a 30- or 90-day time window. ORs decreased consistently in the order of hospital acquisition, HCA, and community acquisition, regardless of time window combination, and differences in area under the ROC curve were immaterial.
authors.affiliation: Center for Clinical Epidemiology, South, Odense University Hospital, and Research Unit of Clinical Epidemiology, Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
authors.forename: Kim Oren
authors.initials: KO
authors.lastname: Gradel
authors.forename: Stig Lønberg
authors.initials: SL
authors.lastname: Nielsen
authors.forename: Court
authors.initials: C
authors.lastname: Pedersen
authors.forename: Jenny Dahl
authors.initials: JD
authors.lastname: Knudsen
authors.forename: Christian
authors.initials: C
authors.lastname: Østergaard
authors.forename: Magnus
authors.initials: M
authors.lastname: Arpi
authors.forename: Thøger Gorm
authors.initials: TG
authors.lastname: Jensen
authors.forename: Hans Jørn
authors.initials: HJ
authors.lastname: Kolmos
authors.forename: Henrik Carl
authors.initials: HC
authors.lastname: Schønheyder
authors.forename: Mette
authors.initials: M
authors.lastname: Søgaard
authors.forename: Annmarie Touborg
authors.initials: AT
authors.lastname: Lassen
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D016470:Bacteremia / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D001419:Bacteria / Q000302:isolation & purification; D015331:Cohort Studies; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D003428:Cross Infection / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology; D003718:Denmark / Q000453:epidemiology; D018562:Disease Transmission, Infectious / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010351:Patient Discharge / Q000706:statistics & numerical data; D011379:Prognosis; D013997:Time Factors