Association between APOE epsilon 4 allele and postoperative cognitive dysfunction: A meta-analysis

Background: Carriers of the apolipoprotein E epsilon 4 allele (APOEe4) 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 APOEe4 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 APOEe4 carriers and 2983 noncarriers were included. At about 1-week postsurgery, a significant association between APOEe4 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...