Kidney Function Modifies the Effect of Intraoperative Opioid Dosage on Postoperative Delirium

Area of Science:

• Geriatric Medicine
• Nephrology
• Anesthesiology

Background:

• Delirium is a significant concern in older surgical patients, particularly those receiving opioid analgesia.
• The impact of baseline kidney function on opioid-induced delirium risk remains understudied in this population.
• Hip fracture surgery in older adults presents a unique context for investigating this relationship.

Purpose of the Study:

• To determine if baseline kidney function influences the association between opioid dosage and the development of delirium on postoperative day 2 (POD2) in hip fracture patients.
• To investigate the role of chronic kidney disease (CKD) in modulating delirium risk following surgery.

Main Methods:

• Retrospective analysis of 652 patients aged 65+ undergoing hip fracture repair without preoperative delirium.
• Assessment of emergency department estimated glomerular filtration rate (eGFR) to categorize patients by presence or absence of CKD.
• Multivariable logistic regression to compare associations between opioid dose (intraoperative, PACU, POD1) and POD2 delirium (assessed using Confusion Assessment Method).

Main Results:

• Postoperative day 2 delirium occurred in 29.8% of patients.
• Intraoperative and PACU opioid doses and ED eGFR did not differ between patients with and without delirium.
• Increased intraoperative opioid dosage significantly raised the odds of POD2 delirium in patients with CKD (OR=1.6), but not in those without CKD (P-interaction=0.04).
• Age, ASA status, and dementia were associated with POD2 delirium.

Conclusions:

• Incremental increases in intraoperative opioids, when combined with chronic kidney disease, elevate the odds of developing postoperative delirium after hip fracture repair.
• This finding highlights the importance of considering kidney function when managing opioid analgesia in elderly surgical patients.
• Further research may explore tailored opioid management strategies based on renal function.