title: The daily risk of bacteremia during hospitalization and associated 30-day mortality evaluated in relation to the traditional classification of bacteremia.
abstract: BACKGROUND
  We investigated the overall and daily incidence of bacteremia among hospitalized patients and evaluated the traditional classification of bacteremia (community-onset vs nosocomial based on a 48-hour time window) by means of the daily incidence and associated 30-day mortality.
  
  
  METHODS
  In a multicenter hospital-based cohort study, we included all patients aged 15 years or older admitted to hospitals in Funen County, Denmark, during 2000-2008, and identified all first bacteremias per admission. We calculated the overall incidence of bacteremia per 1,000 admissions and 10,000 bed-days, as well as the daily incidence of bacteremia per 10,000 bed-days and associated 30-day mortality.
  
  
  RESULTS
  We included 724,339 admissions and 10,281 bacteremias for an overall incidence of 14.2 per 1,000 admissions and 23.6 per 10,000 bed-days. The daily incidence was highest on the first 2 days of admission followed by lower incidences that were constant beyond day 12, but varied according to patient and epidemiologic characteristics. Thirty-day mortality for patients with bacteremia was 18% on day 1, 21% on day 2, and between 25% and 35% thereafter.
  
  
  CONCLUSIONS
  Hospitalized patients were at the highest risk of bacteremia during the first 2 days followed by lower incidences that were constant beyond day 12. Thirty-day mortality was 18%-21% for patients with bacteremia on the first 2 days and 25%-35% thereafter. Our findings support the traditional classification of bacteremia.
authors.affiliation: Department of Infectious Diseases, Odense University Hospital, Odense, Denmark. Electronic address: stig.nielsen@rsyd.dk.
authors.forename: Stig Lønberg
authors.initials: SL
authors.lastname: Nielsen
authors.affiliation: Department of Emergency Medicine, Odense University Hospital, Odense, Denmark.
authors.forename: Annmarie Touborg
authors.initials: AT
authors.lastname: Lassen
authors.affiliation: Department of Clinical Microbiology, Odense University Hospital, Odense, Denmark.
authors.forename: Hans Jørn
authors.initials: HJ
authors.lastname: Kolmos
authors.affiliation: Department of Clinical Microbiology, Odense University Hospital, Odense, Denmark.
authors.forename: Thøger Gorm
authors.initials: TG
authors.lastname: Jensen
authors.affiliation: Center for Clinical Epidemiology, Odense University Hospital, Odense, Denmark; 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.affiliation: Department of Infectious Diseases, Odense University Hospital, Odense, Denmark.
authors.forename: Court
authors.initials: C
authors.lastname: Pedersen
mesh_terms: D000328:Adult; D000368:Aged; D016470:Bacteremia / Q000145:classification / Q000453:epidemiology* / Q000401:mortality; D015331:Cohort Studies; D003428:Cross Infection / Q000145:classification / Q000453:epidemiology* / Q000401:mortality; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006760:Hospitalization; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012306:Risk
keywords: Bloodstream infection; Epidemiology; Incidence; Nosocomial infection