title: Does Apolipoprotein E Genotype Increase Risk of Postoperative Delirium?
abstract: OBJECTIVE
  To determine whether apolipoprotein E (ApoE) is associated with postoperative delirium incidence, severity, and duration in older patients free of dementia at baseline.
  
  
  METHODS
  The authors examined 557 nondemented patients aged 70 years or older undergoing major noncardiac surgery enrolled in the Successful Aging after Elective Surgery Study. Three ApoE measures were considered: ε2, ε4 carriers versus noncarriers, and a three-category ApoE measure. Delirium was determined using the Confusion Assessment Method (CAM) and chart review. We used generalized linear models to estimate the association between ApoE and delirium incidence, severity (peak CAM Severity [CAM-S] score), and days.
  
  
  RESULTS
  ApoE ε2 and ε4 was present in 15% and 19%, respectively, and postoperative delirium occurred in 24%. Among patients with delirium, the mean peak CAM-S score was 8.0 (standard deviation: 4), with most patients experiencing 1 or 2 delirium days (51% or 28%, respectively). After adjusting for age, sex, surgical procedure, and preoperative cognitive function, ApoE ε4 and ε2 carrier status were not associated with postoperative delirium: RR for ε4=1.0, 95% CI: 0.7-1.5 and RR for ε2=0.9, 95% CI: 0.6-1.4. No association between ApoE and delirium severity or number of delirium days was observed.
  
  
  CONCLUSIONS
  In older surgery patients free of dementia, our findings do not support the hypothesis that the ApoE genotype does not confer either risk or protection in postoperative delirium incidence, severity, or duration. Thus, an important genetic risk factor for Alzheimer disease does not affect risk of delirium.
authors.affiliation: Division of General Medicine and Primary Care, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
authors.forename: Sarinnapha
authors.initials: S
authors.lastname: Vasunilashorn
authors.affiliation: Division of General Medicine and Primary Care, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
authors.forename: Long
authors.initials: L
authors.lastname: Ngo
authors.affiliation: Aging Brain Center, Institute for Aging Research, Hebrew SeniorLife, Boston, Massachusetts.
authors.forename: Cyrus M
authors.initials: CM
authors.lastname: Kosar
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
authors.forename: Tamara G
authors.initials: TG
authors.lastname: Fong
authors.affiliation: Aging Brain Center, Institute for Aging Research, Hebrew SeniorLife, Boston, Massachusetts.
authors.forename: Richard N
authors.initials: RN
authors.lastname: Jones
authors.affiliation: Division of Gerontology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
authors.forename: Sharon K
authors.initials: SK
authors.lastname: Inouye
authors.affiliation: Division of General Medicine and Primary Care, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
authors.forename: Edward R
authors.initials: ER
authors.lastname: Marcantonio
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D053329:Apolipoprotein E2 / Q000235:genetics*; D053327:Apolipoprotein E4 / Q000235:genetics*; D003693:Delirium / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D015994:Incidence; D016014:Linear Models; D008297:Male; D011183:Postoperative Complications / Q000453:epidemiology*; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D012307:Risk Factors; D012720:Severity of Illness Index
chemical_list: D053329:Apolipoprotein E2; D053327:Apolipoprotein E4
keywords: Apolipoprotein E; delirium; dementia