title: Subsyndromal delirium in older long-term care residents: incidence, risk factors, and outcomes.
abstract: OBJECTIVE
  To determine the incidence of, risk factors for, and outcomes of subsyndromal delirium (SSD) in older long-term care (LTC) residents and, secondarily, to explore the use of a more-restrictive definition of SSD.
  
  
  METHODS
  Cohort study with repeated weekly assessments for up to 6 months.
  
  
  METHODS
  Seven LTC facilities in Montreal and Quebec City, Canada.
  
  
  METHODS
  One hundred four LTC residents aged 65 and older and free of delirium core symptoms at baseline.
  
  
  METHODS
  The Mini-Mental State Examination (MMSE), Confusion Assessment Method (CAM), Delirium Index (DI), Hierarchic Dementia Scale (HDS), and Barthel Index (BI) were completed at baseline. The MMSE, CAM, and DI were repeated weekly for 6 months. SSD1 required one or more CAM core symptoms; SSD2, a more-restrictive definition, required two or more CAM core symptoms. Outcomes at 6 months were decline on the MMSE, HDS, and BI; mortality; and a composite outcome.
  
  
  RESULTS
  Sixty-eight of 104 residents had SSD1. In survival analysis, the incidence was 5.2 (95% confidence interval (CI) = 4.1-6.7) per 100 person-weeks of follow-up. In multivariate analysis, risk factors were male sex and more-severe cognitive impairment at baseline. The differences in outcomes between residents with and without SSD1 were small and not statistically significant. SSD2 had a lower incidence (1.3, 95% CI = 0.9-1.9), similar risk factors, and statistically significantly worse cognitive outcomes.
  
  
  CONCLUSIONS
  SSD2 appears to be a clinically important disorder in older LTC residents. Despite limited statistical power, these findings have potentially important implications for clinical practice and research in LTC settings.
authors.affiliation: Department of Psychiatry, St. Mary's Research Centre, St. Mary's Hospital, Montreal, Canada. martin.cole@ssss.gouv.qc.ca
authors.forename: Martin G
authors.initials: MG
authors.lastname: Cole
authors.forename: Jane
authors.initials: J
authors.lastname: McCusker
authors.forename: Philippe
authors.initials: P
authors.lastname: Voyer
authors.forename: Johanne
authors.initials: J
authors.lastname: Monette
authors.forename: Nathalie
authors.initials: N
authors.lastname: Champoux
authors.forename: Antonio
authors.initials: A
authors.lastname: Ciampi
authors.forename: Minh
authors.initials: M
authors.lastname: Vu
authors.forename: Eric
authors.initials: E
authors.lastname: Belzile
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D015331:Cohort Studies; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003693:Delirium / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D015140:Dementia, Vascular / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D015577:Geriatric Assessment; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008134:Long-Term Care / Q000706:statistics & numerical data*; D008297:Male; D008609:Mental Status Schedule; D015999:Multivariate Analysis; D011792:Quebec; D012307:Risk Factors