The authors conducted a nested-cohort study of 190 patients, mean age 72.5, who underwent major non-cardiac procedures requiring anesthesia to see whether there is a genetic predisposition to the postop delirium.
To determine the presence of delirium, the investigators interviewed patients by telephone before surgery using the Telephone Interview of Cognitive Status, a validated instrument adapted from the Mini Mental Status Examination. Prior to surgery and on each of the first two postop days, patients were interviewed and their level of delirium (or its lack) was assessed with the Confusion Assessment Method.
Apolipoprotein genotypes were determined from genomic DNA obtained from blood samples. The authors conducted bivariate tests of association between delirium and apolipoprotein genotypes and other potentially important risk factors, and created multivariate logistic regression models to further explore possible associations.
They found that 15.3% of patients had symptoms of delirium on both the first and second postop days, and of this group, 24.2% were found to have at least one copy of the E4 allele.