title: Observational cohort study examining apolipoprotein E status and preoperative neuropsychological performance as predictors of post-operative delirium in an older elective arthroplasty population.
abstract: delirium following surgery is common and is associated with negative outcomes. Preoperative cognitive impairment has been shown to be a risk factor for post-operative delirium. Often the cognitive tests used are cumbersome. This study tests the hypothesis that the quantification of brain vulnerability, using Apolipoprotein E (ApoE) status and neuropsychological tests, both traditional and more easily administered, can quantify the risk of post-operative delirium following elective primary arthroplasty surgery.
  
  
  
  this observational cohort study recruited participants aged 65 years or older admitted prior to elective primary hip or knee arthroplasty. Baseline data was collected and participants underwent neuropsychological testing and had blood taken for ApoE genotyping preoperatively. Post-operatively participants were assessed daily for delirium using the Confusion Assessment Method (CAM) and charts were reviewed where possible for reports of delirium. Univariate and multivariate analyses of preoperative factors were undertaken to identify independent predictors of delirium.
  
  
  
  between March 2012 and October 2014, 315 participants completed the study with an overall incidence of post-operative delirium of 40/315 (12.7%). Of these 18 fulfilled the CAM criteria for delirium and 22 were deemed delirious by consensus decision based on chart review. ApoE genotype was not associated with post-operative delirium in this cohort. Time taken to complete Colour Trails 2, errors in mini mental state examination and level of pain preoperatively were independent predictors of post-operative delirium.
  
  
  
  this study challenges the assertion that ApoE4 genotype predicts post-operative delirium. It replicates previous work suggesting cognitive impairment predicts post-operative delirium and shows for the 1st time that simple cognitive tests can be as effective as more detailed tests.
authors.affiliation: Centre for Public Health, Institute of Clinical Sciences, Block B, Queens University Belfast, Royal Victoria Hospital, Belfast BT12 6BA, UK.
authors.forename: Emma Louise
authors.initials: EL
authors.lastname: Cunningham
authors.affiliation: Belfast Health and Social Care Trust, Belfast, UK.
authors.forename: Tim
authors.initials: T
authors.lastname: Mawhinney
authors.affiliation: Belfast Health and Social Care Trust, Belfast, UK.
authors.forename: David
authors.initials: D
authors.lastname: Beverland
authors.affiliation: Belfast Health and Social Care Trust, Belfast, UK.
authors.forename: Seamus
authors.initials: S
authors.lastname: O'Brien
authors.affiliation: Centre for Experimental Medicine, Queen's University Belfast, Belfast, UK.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: McAuley
authors.affiliation: Northern Health and Social Care Trust, Ballymena, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Cairns
authors.affiliation: Centre for Public Health, Institute of Clinical Sciences, Block B, Queens University Belfast, Royal Victoria Hospital, Belfast BT12 6BA, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Passmore
authors.affiliation: Centre for Public Health, Institute of Clinical Sciences, Block B, Queens University Belfast, Royal Victoria Hospital, Belfast BT12 6BA, UK.
authors.forename: Bernadette
authors.initials: B
authors.lastname: McGuinness
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001057:Apolipoproteins E / Q000235:genetics*; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D016009:Chi-Square Distribution; D003071:Cognition; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D003693:Delirium / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics / Q000523:psychology; D017558:Elective Surgical Procedures; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D000073216:Mental Status and Dementia Tests; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D009660:Northern Ireland / Q000453:epidemiology; D016017:Odds Ratio; D010147:Pain Measurement; D010149:Postoperative Pain / Q000453:epidemiology / Q000523:psychology; D011237:Predictive Value of Tests; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: C000612345:ApoE protein, human; D001057:Apolipoproteins E
keywords: Alzheimer's disease; cognition; delirium; executive dysfunction; older people; orthopaedic; post-operative cognitive dysfunction; post-operative delirium; subsyndromal; surgery