title: The prognostic significance of subsyndromal delirium in elderly medical inpatients.
abstract: OBJECTIVE
  To determine the prognostic significance of subsyndromal delirium (SSD) presentations.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  University-affiliated primary acute care hospital.
  
  
  METHODS
  One hundred sixty-four elderly medical inpatients who did not meet Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised (DSM-III-R) criteria for delirium during the first week after admission were classified into three mutually exclusive groups. The first group, prevalent SSD, included those who had two or more of four core symptoms of delirium (clouding of consciousness, inattention, disorientation, perceptual disturbances) at admission. The second group, incident SSD, included those who did not meet criteria for prevalent SSD but displayed one or more new core symptoms during the week after admission. The third group had no prevalent or incident SSD. The three groups were followed up at 2, 6, and 12 months.
  
  
  METHODS
  Outcomes (length of stay, symptoms of delirium (Delirium index), cognitive (Mini-Mental State Examination) and functional status (instrumental activities of daily living), and mortality) were compared using univariate techniques and multivariate regression models that adjusted for age, sex, marital status, living arrangements before admission, comorbidity, clinical and physiological severity of illness, and dementia status and severity.
  
  
  RESULTS
  Patients with prevalent SSD had longer acute care hospital stay, increased postdischarge mortality, more symptoms of delirium, and a lower cognitive and functional level at follow-up than patients with no SSD. Most of the findings for incident SSD were similar but not statistically significant. Patients with prevalent or incident SSD had risk factors for DSM-defined delirium.
  
  
  CONCLUSIONS
  SSD in elderly medical inpatients appears to be a clinically important syndrome that falls on a continuum between no symptoms and DSM-defined delirium.
authors.affiliation: Department of Psychiatry, St. Mary's Hospital and McGillUniversity, Montreal, Quebec. dcecs@smhc.qc.ca
authors.forename: Martin
authors.initials: M
authors.lastname: Cole
authors.forename: Jane
authors.initials: J
authors.lastname: McCusker
authors.forename: Nandini
authors.initials: N
authors.lastname: Dendukuri
authors.forename: Ling
authors.initials: L
authors.lastname: Han
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D017281:Cost of Illness; D003693:Delirium / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006304:Health Status; D006801:Humans; D007902:Length of Stay; D008297:Male; D011379:Prognosis