title: Hospital use, institutionalisation and mortality associated with delirium.
abstract: BACKGROUND
  Delirium is a disorder affecting consciousness, which gives rise to core clinical features and associated symptoms. Older patients are particularly prone, owing to higher rates of pre-existing cognitive impairment, frailty, co-morbidity and polypharmacy.
  
  
  OBJECTIVE
  The aim of this study was to investigate the hypotheses that delirium affects the most vulnerable older adults and is associated with long-term adverse health outcome.
  
  
  METHODS
  This prospective cohort study evaluated 278 medical patients aged > or = 75 years admitted acutely to a district general hospital in South Wales. Patients were screened for delirium at presentation and on alternate days throughout their hospital stay. Assessments also included illness severity, preadmission cognition, co-morbidity and functional status. Patients were followed for 5 years to determine rates of institutionalisation and mortality. Number of days in hospital in the 4 years prior to and 5 years after index admission were recorded.
  
  
  RESULTS
  Delirium was detected in 103 patients and excluded in 175. Median time to death was 162 days (interquartile range 21-556) for those with delirium compared with 1,444 days (25% mortality 435 days, 75% mortality>5 years) for those without (P < 0.001). After adjusting for multiple confounders, delirium was associated with an increased risk of death (hazard ratio range 2.0-3.5; P < or = 0.002). Institutionalisation was higher in the first year following delirium (P = 0.03). While those with delirium tended to be older with more preadmission cognitive impairment, greater functional dependency and more co-morbidity, they did not spend more days in hospital in the 4 years prior to index admission.
  
  
  CONCLUSIONS
  Delirium is associated with high rates of institutionalisation and an increased risk of death up to 5 years after index event. Prior to delirium, individuals seem to compensate for their vulnerability. The impact of delirium itself, directly or indirectly, may convert vulnerability into adverse outcome.
authors.affiliation: Department of Geriatric Medicine, Cardiff University, Academic Centre, University Hospital Llandough, Penarth, South Wales, UK. eamonn.eeles2@wales.nhs.uk <eamonn.eeles2@wales.nhs.uk>
authors.forename: Eamonn M P
authors.initials: EM
authors.lastname: Eeles
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Hubbard
authors.forename: Susan V
authors.initials: SV
authors.lastname: White
authors.forename: M Sinead
authors.initials: MS
authors.lastname: O'Mahony
authors.forename: George M
authors.initials: GM
authors.lastname: Savva
authors.forename: Antony J
authors.initials: AJ
authors.lastname: Bayer
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000453:epidemiology; D015331:Cohort Studies; D003693:Delirium / Q000401:mortality*; D005260:Female; D016330:Frail Elderly / Q000706:statistics & numerical data; D015577:Geriatric Assessment / Q000706:statistics & numerical data; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data*; D008297:Male; D019338:Polypharmacy; D011446:Prospective Studies; D012720:Severity of Illness Index; D014852:Wales / Q000453:epidemiology