Aging & Gerontology

Abstract

BACKGROUND: Delirium is categorized by acute changes in attention, cognition, and awareness that are not explained by pre-existing medical conditions. Its etiology remains poorly understood. Delirium occurs in around 21-25% of older patients after elective surgery. Delirium is associated with increased risk for post-discharge mortality, dementia, long-term cognitive decline, and other poor outcomes. This study focuses on a previously identified neurodegenerative marker that is associated with delirium. APOe4 has been found to increase the risk for delirium, but not all patients with the APOe4 allele experienced delirium. This suggests that mechanisms underlying delirium are multifactorial. Recent literature has suggested that chronic conditions are associated with the onset and progression of neurodegenerative diseases. It is not known whether the combination of chronic conditions and APOe4 infers a greater risk for delirium than either variable alone.
OBJECTIVE: 
Question: What is the association between APOe4 and postoperative delirium after considering presence of chronic conditions?
Hypothesis: Both chronic conditions and APOe4 will be associated with postoperative delirium.
METHODS: This is a secondary analysis of data from 2001-2014 at the University of California, San Francisco. The inclusion criteria are:
- >= 65 year old
- Major elective noncardiac surgery requiring anesthesia
- Expected to remain in the hospital postoperatively for more than 48 hrs.
- None were delirious at admission
The study included 351 elective surgery patients. Each patient is interviewed by the same research assistant preoperatively and postoperatively. Data collected from each patient include:
- APOe4 allele status
- Medical history
- The measured outcome, delirium status (Confusion Assessment Method)
148 of the patients analyzed in this study were also included in a prior study (Leung et al., 2007) investigating the risk of postoperative delirium in older patients undergoing noncardiac elective surgery.
RESULTS: 30.2% of patients in this sample were over the age of 75. 15.4% of patients had at least one APOe4 allele, while 84.6% did not. 28.5% of patients had a Charlson Comorbidity Index (CCI) > 1, while 71.5% had a CCI of 0 or 1. 32.8% of patients had postoperative delirium. There is an association between higher number of comorbidities and postoperative delirium (OR = 1.70, CI = 1.03 - 2.82). After controlling for confounding variables (comorbidities and age), the association between APOe4 and postoperative delirium (OR = 0.50, CI = 0.21 - 1.23) was not statistically significant. This indicates that increased comorbidities and increased age have a greater impact on postoperative delirium than APOe4 in this cohort.
DISCUSSION: Increased comorbidities are associated with postoperative delirium in non-cardiac elective surgery patients over age 65. This relationship can be used to inform clinical recommendations and aid in determining preventable risk.

SUMMARY:
This study investigated the association between the APOe4 allele, chronic conditions, and postoperative delirium in 351 elective, noncardiac surgery patients aged 65 and above who did not have dementia. There is an association between higher number of comorbidities and postoperative delirium (OR = 1.70, CI = 1.03 - 2.82). After controlling for confounding variables (comorbidities and age), the association between APOe4 and postoperative delirium (OR = 0.50, CI = 0.21 - 1.23) was not statistically significant. This indicates that increased comorbidities and increased age have a greater impact on postoperative delirium than APOe4 in this cohort

Biography

TBA