title: Incidence and short-term consequences of delirium in critically ill patients: A prospective observational cohort study.
abstract: BACKGROUND
  Delirium is a serious and frequent psycho-organic disorder in critically ill patients. Reported incidence rates vary to a large extent and there is a paucity of data concerning delirium incidence rates for the different subgroups of intensive care unit (ICU) patients and their short-term health consequences.
  
  
  OBJECTIVE
  To determine the overall incidence and duration of delirium, per delirium subtype and per ICU admission diagnosis. Furthermore, we determined the short-term consequences of delirium.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  All adult consecutive patients admitted in one year to the ICU of a university medical centre.
  
  
  METHODS
  Delirium was assessed using the Confusion Assessment Method-ICU three times a day. Delirium was divided in three subtypes: hyperactive, hypoactive and mixed subtype. As measures for short-term consequences we registered duration of mechanical ventilation, re-intubations, incidence of unplanned removal of tubes, length of (ICU) stay and in-hospital mortality.
  
  
  RESULTS
  1613 patients were included of which 411 (26%) developed delirium. The incidence rate in the neurosurgical (10%) and cardiac surgery group (12%) was the lowest, incidence was intermediate in medical patients (40%), while patients with a neurological diagnosis had the highest incidence (64%). The mixed subtype occurred the most (53%), while the hyperactive subtype the least (10%). The median delirium duration was two days [IQR 1-7], but significantly longer (P<0.0001) for the mixed subtype. More delirious patients were mechanically ventilated and for a longer period of time, were more likely to remove their tube and catheters, stayed in the ICU and hospital for a longer time, and had a six times higher chance of dying compared to non-delirium ICU patients, even after adjusting for their severity of illness score. Delirium was associated with an extended duration of mechanical ventilation, length of stay in the ICU and in-hospital, as well as with in-hospital mortality.
  
  
  CONCLUSIONS
  The delirium incidence in a mixed ICU population is high and differs importantly between ICU admission diagnoses and the subtypes of delirium. Patients with delirium had a significantly higher incidence of short-term health problems, independent from their severity of illness and this was most pronounced in the mixed subtype of delirium. Delirium is significantly associated with worse short-term outcome.
authors.affiliation: Department of Intensive Care Medicine, Radboud University Nijmegen Medical Centre, The Netherlands. m.vandenboogaard@ic.umcn.nl
authors.forename: Mark
authors.initials: M
authors.lastname: van den Boogaard
authors.forename: Lisette
authors.initials: L
authors.lastname: Schoonhoven
authors.forename: Johannes G
authors.initials: JG
authors.lastname: van der Hoeven
authors.forename: Theo
authors.initials: T
authors.lastname: van Achterberg
authors.forename: Peter
authors.initials: P
authors.lastname: Pickkers
mesh_terms: D016638:Critical Illness; D003693:Delirium / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D011446:Prospective Studies