title: Prognostic Significance of Postoperative Subsyndromal Delirium.
abstract: BACKGROUND
  Whether postoperative subsyndromal delirium (SSD) is a separate syndrome from delirium and has clinical relevance is not well understood.
  
  
  OBJECTIVE
  We sought to investigate SSD in older surgical patients and to determine its prognostic significance.
  
  
  METHODS
  We performed a prospective cohort study of patients who were 65 years or older and were scheduled for noncardiac surgery. Postoperative delirium was determined using the Confusion Assessment Method. SSD was defined as the presence of at least one of the possible 10 symptoms of delirium, as defined by the Confusion Assessment Method, but not meeting the criteria for delirium.
  
  
  RESULTS
  The number of features of SSD on the first postoperative day was associated with the subsequent development of delirium on the next day, after controlling for other risk factors. When compared with a patient with no SSD features, a patient with 1 SSD feature was 1.07 times more likely to have delirium on the next day (95% CI: 0.42-2.53), with 2 features was 3.32 times more likely to have it (95% CI: 1.42-7.57), and with ≥ 2 features was 8.37 times more likely to have it (95% CI: 4.98-14.53). Furthermore, there was a significant relationship between the number of features of SSD and increased length of hospital stay and worsened functional status at 1 month after surgery.
  
  
  CONCLUSIONS
  SSD is prevalent in at-risk surgical patients and has prognostic significance. Only a single symptom of SSD was sufficient to cause a significant increase in hospital length of stay and further decline in functional status. These results suggest that monitoring for SSD is indicated in at-risk patients.
authors.affiliation: Psychiatry, University of California, San Francisco, CA.
authors.forename: Jewel
authors.initials: J
authors.lastname: Shim
authors.affiliation: Statistics, Purdue University, San Francisco, CA.
authors.forename: Glen
authors.initials: G
authors.lastname: DePalma
authors.affiliation: Center for Gerontology, Virginia Tech University, San Francisco, CA.
authors.forename: Laura P
authors.initials: LP
authors.lastname: Sands
authors.affiliation: Anesthesia and Perioperative Care, University of California, San Francisco, CA. Electronic address: jacqueline.leung@ucsf.edu.
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Leung
mesh_terms: D000368:Aged; D000768:Anesthesia, General / Q000009:adverse effects*; D015331:Cohort Studies; D003693:Delirium / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D011183:Postoperative Complications / Q000453:epidemiology*; D015995:Prevalence; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D013514:Surgical Procedures, Operative / Q000009:adverse effects*