title: Cognitive and functional status predictors of delirium and delirium severity after coronary artery bypass graft surgery: an interim analysis of the Neuropsychiatric Outcomes After Heart Surgery study.
abstract: BACKGROUND
  Cognitive and functional impairment increase risk for post-coronary artery bypass graft (CABG) surgery delirium (PCD), but how much impairment is necessary to increase PCD risk remains unclear.
  
  
  METHODS
  The Neuropsychiatric Outcomes After Heart Surgery (NOAHS) study is a prospective, observational cohort study of participants undergoing elective CABG surgery. Pre-operative cognitive and functional status based on Clinical Dementia Rating (CDR) scale and neuropsychological battery are assessed. We defined mild cognitive impairment (MCI) based on either (1) CDR global score 0.5 (CDR-MCI) or (2) performance 1.5 SD below population means on any cognitive domain on neurocognitive battery (MCI-NC). Delirium was assessed daily post-operative day 2 through discharge using the confusion assessment method (CAM) and delirium index (DI). We investigate whether MCI - either definition - predicts delirium or delirium severity.
  
  
  RESULTS
  So far we have assessed 102 participants (mean age 65.1 ± 9; male: 75%) for PCD. Twenty six participants (25%) have MCI-CDR; 38 (62% of those completing neurocognitive testing) met MCI-NC criteria. Fourteen participants (14%) developed PCD. After adjusting for age, sex, comorbidity, and education, MCI-CDR, MMSE, and Lawton IADL score predicted PCD on logistic regression (OR: 5.6, 0.6, and 1.5, respectively); MCI-NC did not (OR [95% CI]: 11.8 [0.9, 151.4]). Using similarly adjusted linear regression, MCI-CDR, MCI-NC, CDR sum of boxes, MMSE, and Lawton IADL score predicted delirium severity (adjusted R(2): 0.26, 0.13, 0.21, 0.18, and 0.32, respectively).
  
  
  CONCLUSIONS
  MCI predicts post-operative delirium and delirium severity, but MCI definition alters these relationships. Cognitive and functional impairment independently predict post-operative delirium and delirium severity.
authors.affiliation: Psychological Medicine Section,Yale School of Medicine,New Haven,CT,USA.
authors.forename: Mark A
authors.identifier: http://orcid.org/0000-0002-0981-7522
authors.initials: MA
authors.lastname: Oldham
authors.affiliation: Psychological Medicine Section,Yale School of Medicine,New Haven,CT,USA.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Hawkins
authors.affiliation: Section of Cardiac Surgery,Yale School of Medicine,New Haven,CT,USA.
authors.forename: David D
authors.initials: DD
authors.lastname: Yuh
authors.affiliation: Section of Cardiac Surgery,Yale School of Medicine,New Haven,CT,USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Dewar
authors.affiliation: Section of Cardiac Surgery,Yale School of Medicine,New Haven,CT,USA.
authors.forename: Umer M
authors.initials: UM
authors.lastname: Darr
authors.affiliation: Section of Cardiac Surgery,Yale School of Medicine,New Haven,CT,USA.
authors.forename: Taras
authors.initials: T
authors.lastname: Lysyy
authors.affiliation: Psychological Medicine Section,Yale School of Medicine,New Haven,CT,USA.
authors.forename: Hochang B
authors.initials: HB
authors.lastname: Lee
mesh_terms: D000368:Aged; D060825:Cognitive Dysfunction / Q000175:diagnosis*; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D003693:Delirium / Q000175:diagnosis*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011183:Postoperative Complications; D011379:Prognosis; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D012720:Severity of Illness Index; D016896:Treatment Outcome
keywords: CABG; delirium; functional status; neurocognitive impairment; neuropsychological testing