The Impact of Postoperative Pain on the Development of Postoperative Delirium

TLDR

The prospective observational study examined how postoperative pain and its treatment affect delirium development in noncardiac surgery patients, measuring pain with a visual analog scale and diagnosing delirium using the confusion assessment method and medical records. Daily interviews captured pain at rest, with movement, and maximal pain, while recording postoperative analgesia type, opioid type, and cumulative dose. After controlling for preoperative risk factors, higher rest pain scores were associated with increased delirium risk (adjusted RR 1.20, P = 0.04), whereas pain with movement, maximal pain, analgesia method, opioid type, and cumulative dose were not linked to delirium, suggesting that better pain control may reduce its incidence. Anesth Analg 1998;86:781‑5.

Abstract

We performed a prospective observational study to examine the role of postoperative pain and its treatment on the development of postoperative delirium.Pain was measured in direct patient interviews using a visual analog scale (VAS) and was assessed for pain at rest, pain with movement, and maximal pain over the previous 24 h. Postoperative delirium was diagnosed during these interviews by using the confusion assessment method (CAM) and/or by using data from the medical record and the hospital's nursing intensity index. Postoperative analgesia, type of opioid, and cumulative opioid dose were also recorded. After controlling for known preoperative risk factors for delirium (age, alcohol abuse, cognitive function, physical function, serum chemistries, and type of surgery), higher pain scores at rest was associated with an increased risk of delirium over the first 3 postoperative days (adjusted risk ratio 1.20, P = 0.04). Pain with movement and maximal pain were not associated with delirium. Method of postoperative analgesia, type of opioid, and cumulative opioid dose were not associated with an increased risk of delirium. We conclude that more effective control of postoperative pain reduces the incidence of postoperative delirium. Implications: We performed daily interviews in a large population of patients undergoing noncardiac surgery to measure their level of pain and development of delirium. We found an association between higher pain levels at rest and the development of delirium. Our results suggest that better control of postoperative pain may reduce this serious complication. (Anesth Analg 1998;86:781-5)