title: ARDS of early or late onset: does it make a difference?
abstract: BACKGROUND
  Differences in outcomes have been demonstrated for critically ill patients with late-onset compared with early-onset renal failure and late-onset compared with early-onset shock, which could cause a lead-time bias in clinical trials assessing potential therapies for these conditions. We used data from a large, multicenter observational study to assess whether late-onset ARDS was similarly associated with worse outcomes compared with early-onset ARDS.
  
  
  METHODS
  Data were extracted from the Sepsis Occurrence in Acutely Ill Patients (SOAP) study, which involved 198 ICUs from 24 European countries. All adult patients admitted to a participating ICU between May 1, 2002 and May 15, 2002, were eligible, except those admitted for uncomplicated postoperative surveillance. Early/late onset acute lung injury (ALI)/ARDS was defined as ALI/ARDS occurring within/after 48 h of ICU admission.
  
  
  RESULTS
  Of the 3,147 patients included in the SOAP study, 393 (12.5%) had a diagnosis of ALI/ARDS; 254 had early-onset ALI/ARDS (64.6%), and 139 (35.5%) late-onset. Patients with early-onset ALI/ARDS had higher Simplified Acute Physiology II scores on admission and higher initial Sequential Organ Failure Assessment scores. Patients with late-onset ALI/ARDS had longer ICU and hospital lengths of stay than patients with early-onset ALI/ARDS. ICU and hospital mortality rates were, if anything, lower in late-onset ALI/ARDS than in early-onset ALI/ARDS, but these differences were not statistically significant.
  
  
  CONCLUSIONS
  There were no significant differences in mortality rates between early- and late-onset ARDS, but patients with late-onset ALI/ARDS had longer ICU and hospital lengths of stay.
authors.affiliation: Department of Intensive Care, Erasme University Hospital, Route de Lennik 808, B-1070 Brussels, Belgium;jlvincen@ulb.ac.be
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Vincent
authors.forename: Yasser
authors.initials: Y
authors.lastname: Sakr
authors.forename: Johan
authors.initials: J
authors.lastname: Groeneveld
authors.forename: Durk F
authors.initials: DF
authors.lastname: Zandstra
authors.forename: Eric
authors.initials: E
authors.lastname: Hoste
authors.forename: Yannick
authors.initials: Y
authors.lastname: Malledant
authors.forename: Katie
authors.initials: K
authors.lastname: Lei
authors.forename: Charles L
authors.initials: CL
authors.lastname: Sprung
mesh_terms: D017668:Age of Onset; D000368:Aged; D005060:Europe / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D017052:Hospital Mortality / Q000639:trends; D006801:Humans; D015994:Incidence; D007362:Intensive Care Units / Q000706:statistics & numerical data; D007902:Length of Stay / Q000639:trends; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012128:Respiratory Distress Syndrome / Q000453:epidemiology*; D015996:Survival Rate / Q000639:trends