title: Obstructive sleep apnea and incidence of postoperative delirium after elective knee replacement in the nondemented elderly.
abstract: BACKGROUND
  Postoperative delirium, a common complication in the elderly, can occur following any type of surgery and is associated with increased morbidity and mortality; it may also be associated with subsequent cognitive problems. Effective therapy for postoperative delirium remains elusive because the causative factors of delirium are likely multiple and varied.
  
  
  METHODS
  Patients 65 yr or older undergoing elective knee arthroplasty were prospectively evaluated for postoperative Diagnostic and Statistical Manual of Mental Disorders-IV delirium. Exclusion criteria included dementia, mini-mental state exam score less than 24, delirium, clinically significant central nervous system/neurologic disorder, current alcoholism, or any serious psychiatric disorder. Delirium was assessed on postoperative days 2 and 3 using standardized scales. Patients' preexisting medical conditions were obtained from medical charts. The occurrence of obstructive sleep apnea was confirmed by contacting patients to check their polysomnography records. Data were analyzed using Pearson chi-square or Wilcoxon rank sum tests and multiple logistic regressions adjusted for effects of covariates.
  
  
  RESULTS
  Of 106 enrolled patients, 27 (25%) developed postoperative delirium. Of the 15 patients with obstructive sleep apnea, eight (53%) experienced postoperative delirium, compared with 19 (20%) of the patients without obstructive sleep apnea (P = 0.0123, odds ratio: 4.3). Obstructive sleep apnea was the only statistically significant predictor of postoperative delirium in multivariate analyses.
  
  
  CONCLUSIONS
  This is the first prospective study employing validated measures of delirium to identify an association between preexisting obstructive sleep apnea and postoperative delirium.
authors.affiliation: School of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Flink
authors.forename: Sarah K
authors.initials: SK
authors.lastname: Rivelli
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Cox
authors.forename: William D
authors.initials: WD
authors.lastname: White
authors.forename: Grace
authors.initials: G
authors.lastname: Falcone
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Vail
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Young
authors.forename: Michael P
authors.initials: MP
authors.lastname: Bolognesi
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Krystal
authors.forename: Paula T
authors.initials: PT
authors.lastname: Trzepacz
authors.forename: Richard E
authors.initials: RE
authors.lastname: Moon
authors.forename: Madan M
authors.initials: MM
authors.lastname: Kwatra
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D003693:Delirium / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D017558:Elective Surgical Procedures / Q000009:adverse effects*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D011446:Prospective Studies; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology*; D011795:Surveys and Questionnaires