title: A systematic review and meta-analysis of the association between the apolipoprotein E genotype and delirium.
abstract: The role of apolipoprotein E (APOE) in Alzheimer's disease and other dementias has been investigated intensively. However, the relationship between APOE and delirium has only recently been explored in studies that have included relatively small samples. A meta-analysis of the published pooled data is timely to explore the relationship between APOE and delirium and to inform further research in this topic. PubMed, EBSCOhost, Google Scholar, Scopus, all EBM Reviews (OVID) and the Cochrane Database of Systematic Reviews were searched with relevant keywords and from the references of relevant papers. Ten papers were found that examined the relationship between APOE and delirium. Data were extracted from eight of them and pooled for meta-analysis using random effects with R software. Data from 1762 participants, of whom 479 (27.2%) were diagnosed with delirium, showed low heterogeneity (Q=13.11, d.f.=7, P=0.07; I=44.86%). The possession of the APOE ε4 allele has a small (log odds ratio: 0.18, 95% confidence interval: 0.23-0.59), nonsignificant (P=0.38) effect on the presence of delirium. No publication bias was identified. The metapower of the pooled data was low (α=0.05, power=0.65). On analysing the studies to date, it seems that there is no association between APOE and the occurrence of delirium. We suggest that further studies are needed with greater number of patients to clarify any association as well as to examine for other patterns of association including relevance for subgroups of patients who develop delirium and for effects on the phenotype of delirium and the outcomes.
authors.affiliation: aSligo Mental Health Services bPathology Department, Sligo Regional Hospital, Sligo cCognitive Impairment Research Group (CIRG), Graduate-Entry Medical School University of Limerick, Limerick dSligo Medical Academy, NUI Galway, Galway, Ireland eResearch and Academic Institute of Athens, Athens, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Adamis
authors.forename: David
authors.initials: D
authors.lastname: Meagher
authors.forename: John
authors.initials: J
authors.lastname: Williams
authors.forename: Owen
authors.initials: O
authors.lastname: Mulligan
authors.forename: Geraldine
authors.initials: G
authors.lastname: McCarthy
mesh_terms: D000483:Alleles; D000544:Alzheimer Disease / Q000235:genetics; D053327:Apolipoprotein E4 / Q000235:genetics*; D003693:Delirium / Q000235:genetics*; D005838:Genotype; D006801:Humans; D016017:Odds Ratio
chemical_list: D053327:Apolipoprotein E4