title: Subsyndromal delirium in the ICU: evidence for a disease spectrum.
abstract: OBJECTIVE
  ICU delirium is common and adverse. The Intensive Care Delirium Screening Checklist (ICDSC) score ranges from 0 to 8, with a score of 4 or higher indicating clinical delirium. We investigated whether lower (subsyndromal) values affect outcome.
  
  
  METHODS
  600 patients were evaluated with the ICDSC every 8[Symbol: see text]h.
  
  
  RESULTS
  Of 558 assessed patients 537 noncomatose patients were divided into three groups: no delirium (score = 0; n = 169, 31.5%), subsyndromal delirium (score = 1-3; n = 179, 33.3%), and clinical delirium (score >or=4; n = 189, 35.2%). ICU mortality rates were 2.4%, 10.6%, and 15.9% in these three groups, respectively. Post-ICU mortality was significantly greater in the clinical delirium vs. no delirium groups (hazard ratio = 1.67) after adjusting for age, APACHE II score, and medication-induced coma. Relative ICU length of stay was: no delirium < subsyndromal delirium < clinical delirium and hospital LOS: no delirium < subsyndromal delirium approximately clinical delirium. Patients with no delirium were more likely to be discharged home and less likely to need convalescence or long-term care than those with subsyndromal delirium or clinical delirium. ICDSC score increments higher than 4/8 were not associated with a change in mortality or LOS.
  
  
  CONCLUSIONS
  Clinical delirium is common, important and adverse in the critically ill. A graded diagnostic scale permits detection of a category of subsyndromal delirium which occurs in many ICU patients, and which is associated with adverse outcome.
authors.affiliation: Maisonneuve-Rosemont Hospital and Université de Montréal, Intensive Care Unit, 5415 Boulevard del'Assomption, H1T 2M4, Montreal, QC, Canada.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Ouimet
authors.forename: Richard
authors.initials: R
authors.lastname: Riker
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bergeron
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bergeon
authors.forename: Mariève
authors.initials: M
authors.lastname: Cossette
authors.forename: Brian
authors.initials: B
authors.lastname: Kavanagh
authors.forename: Yoanna
authors.initials: Y
authors.lastname: Skrobik
mesh_terms: D000368:Aged; D003693:Delirium / Q000503:physiopathology*; D019317:Evidence-Based Medicine; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units; D007902:Length of Stay; D008297:Male; D008485:Medical Audit; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011792:Quebec / Q000453:epidemiology; D012720:Severity of Illness Index