title: Sensitivity and specificity of the animal fluency test for predicting postoperative delirium.
abstract: BACKGROUND
  Preoperative cognitive impairment is a major risk factor for postoperative delirium. We therefore investigated the prognostic significance and feasibility of administering a brief cognitive screen before surgery.
  
  
  METHODS
  Patients > 65 yr of age undergoing hip, knee, or spine surgery were enrolled. A 60-sec cognitive screen, the animal fluency test (AFT), was administered preoperatively. Postoperative delirium was measured using a chart-based tool previously validated using criteria from the Confusion Assessment Method.
  
  
  RESULTS
  Of the 362 patients satisfying the inclusion/exclusion criteria, 199 (55%) underwent the AFT. Among them, 57 patients (29%) had an AFT score < 15, and 38 patients (19%, 95% confidence interval [CI]: 14 to 25%) developed postoperative delirium as measured by chart review. Patients with scores of < 15 were more likely to develop postoperative delirium than those who scored ≥ 15 (54% vs 5%, P < 0.01). A multiple logistic regression, with postoperative delirium as the dependent variable, identified an AFT score of < 15 (odds ratio 20.1, 95% CI: 7.9 to 51.4) and high American Society of Anesthesiologists classification (odds ratio 3.5, 95% CI: 1.3 to 9.2) as independent predictors.
  
  
  CONCLUSIONS
  The AFT is a potentially useful brief cognitive screen for identifying patients at risk of developing postoperative delirium. Limited participation by eligible participants in this study, however, raises questions about how useful and feasible systematic administration of the test is. Large studies using prospective measurement of postoperative delirium are indicated to validate our results.
authors.affiliation: Department of Anesthesia and Perioperative Care, University of California San Francisco, 521 Parnassus Ave, C-455, San Francisco, CA, 94143-0648, USA, longs1@anesthesia.ucsf.edu.
authors.forename: Lawrence S
authors.initials: LS
authors.lastname: Long
authors.forename: Jed T
authors.initials: JT
authors.lastname: Wolpaw
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Leung
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000150:complications / Q000175:diagnosis*; D003693:Delirium / Q000209:etiology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D011183:Postoperative Complications / Q000209:etiology*; D011300:Preoperative Care / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity