title: Association between APOE epsilon 4 allele and postoperative cognitive dysfunction: a meta-analysis.
abstract: BACKGROUND
  Carriers of the apolipoprotein E epsilon 4 allele (APOEε4) may be at increased risk of postoperative cognitive dysfunction (POCD), but this association has not been reported consistently. We conducted a meta-analysis to derive a more precise conclusion.
  
  
  METHODS
  The PubMed, EBSCO and EMBASE databases were searched for eligible studies published in English before March 2013. The association between APOEε4 and POCD was expressed by the odds ratio (OR) with 95% confidence interval (CI). Funnel plots were constructed and publication bias assessed by Egger's test.
  
  
  RESULTS
  Nine studies encompassing 1063 APOEε4 carriers and 2983 noncarriers were included. At about 1-week postsurgery, a significant association between APOEε4 and POCD was found (OR 1.83, 95% CI: 1.18-2.85), but the association was no longer significant after removing one large study (OR 1.35, 95% CI: 0.92-1.97). Stratified analysis of cardiac/vascular surgery patients also yielded no significant correlation (OR 1.62, 95% CI: 0.80-3.28). One to three months postsurgery, neither the overall analysis (OR 1.56, 95% CI: 0.87-2.81) nor the stratified analysis of cardiac/vascular surgery patients (OR 3.33, 95% CI: 0.55-20.22) indicated a significant correlation. APOEε4 was also not correlated with POCD at 1-year postsurgery (OR 1.15, 95% CI: 0.71-1.86). No evidence of publication bias was revealed by Egger's test.
  
  
  CONCLUSIONS
  The APOEε4 allele was associated with a significantly increased POCD risk about 1-week postsurgery, but the association depended on one large study. No association was found 1-3 months and 1-year postsurgery.
authors.affiliation: 1Department of Intensive Care Unit, The Second Affiliated Hospital of Nantong University, Nantong, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Cao
authors.forename: Kai
authors.initials: K
authors.lastname: Wang
authors.forename: Tianyu
authors.initials: T
authors.lastname: Gu
authors.forename: Boxiang
authors.initials: B
authors.lastname: Du
authors.forename: Jie
authors.initials: J
authors.lastname: Song
mesh_terms: D000483:Alleles; D001057:Apolipoproteins E / Q000235:genetics*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D003072:Cognition Disorders / Q000209:etiology / Q000235:genetics*; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006801:Humans
chemical_list: D001057:Apolipoproteins E
keywords: allele; apolipoprotein E; gene polymorphism; meta-analysis; postoperative cognitive dysfunction