Does preoperative risk for delirium moderate the effects of postoperative pain and opiate use on postoperative delirium?

OBJECTIVES: To investigate whether preoperative risk for delirium moderates the effect of postoperative pain and opioids on the development of postoperative delirium. DESIGN: Prospective cohort study. SETTING: University medical center. PARTICIPANTS: Patients 65 years of age or older scheduled for major noncardiac surgery. MEASUREMENTS: A structured interview was conducted preoperatively and postoperatively to determine the presence of delirium, defined using the Confusion Assessment Method. We first developed a prediction model to determine which patients were at high versus low risk for the development of delirium based on preoperative patient data. We then computed a logistic regression model to determine whether preoperative risk for delirium moderates the effect of postoperative pain and opioids on incident delirium. RESULTS: Of 581 patients, 40% developed delirium on days 1 or 2 after surgery. Independent preoperative predictors of postoperative delirium included lower cognitive status, a history of central nervous system disease, high surgical risk, and major spine and joint arthroplasty surgery. Compared with the patients at low preoperative risk for developing delirium, the relative risk for postoperative delirium for those in the high preoperative risk group was 2.38 (95% confidence interval: 1.67-3.40). A significant three-way interaction indicates that preoperative risk for delirium significantly moderated the effect of postoperative pain and opioid use on the development of delirium. Among patients at high preoperative risk for development of delirium who also had high postoperative pain and received high opioid doses, the incidence of delirium was 72%, compared with 20% among patients with low preoperative risk, low postoperative pain, and those who received low opioid doses. CONCLUSIONS: High levels of postoperative pain and using high opioid doses increased risk for postoperative delirium for all patients. The highest incidence of delirium was among patients who had high preoperative risk for delirium and also had high postoperative pain and used high opioid doses.

Brief report: preoperative frailty in older surgical patients is associated with early postoperative delirium.

We investigated whether preoperative frailty among older noncardiac surgical patients provides information about the development of postoperative delirium that is in addition to traditional geriatric risk factors. One-third of patients had a frailty score ≥3, which is considered "frail" in others' research. Twenty-five percent of patients developed postoperative delirium, which was measured using the confusion assessment method. Multivariable logistic regression showed that age, activities of daily living dependence, instrumental activities of daily living dependence, and cognitive functioning did not contribute significantly to the prediction of postoperative delirium. Only preoperative symptoms of depression (odds ratio=1.42; 95% confidence interval=1.06-1.91; P=0.018) and the frailty score (odds ratio=1.84; 95% confidence interval=1.07-3.1; P=0.028) were independently associated with the development of postoperative delirium.

Factors associated with recovery from early postoperative delirium.

Delirium occurs in 14% to 56% of postoperative, hospitalized elderly persons, making it one of the most common postoperative complications for the older patient. The aim of this study was to determine factors associated with recovery of delirium from postoperative day one (POD 1) to postoperative day two (POD 2). The hypothesis was that those with less pain are more likely to recover from delirium by POD 2. Patients aged 65 or older who were scheduled for noncardiac surgery, spoke English, and developed delirium on POD 1 as detected by the Confusion Assessment Method (CAM) were included (n = 176). Postoperative delirium on POD 2 was also measured with the CAM. Postoperative pain was assessed on PODs 1 and 2 using the Numeric Rating Scale (NRS). One hundred seventy-six patients developed delirium on POD 1, with 66 (38%) recovering from delirium by POD 2. The mean age of those patients who recovered from delirium was 72.5 ± 5.7 (n = 66), whereas the mean age of those patients who did not recover from delirium was 75.9 ± 6.5 (n = 110). Multivariate logistic regression revealed that patients less than age 75 were more likely to recover from delirium (OR = 2.31; 95% CI = 1.18-4.53; P = .015), as were patients who had pain scores of less than 5 on POD 2 (OR = 2.59; 95% CI = 1.26-5.35; P = .0098). Patients with lower pain levels (NRS ≤4) were also more likely to recover from delirium on POD 2. The type of postoperative pain therapy (the use or nonuse of patient-controlled analgesia) was not related to delirium recovery. The results suggest that aggressive pain management in the first 48 hours postoperatively may be important in promoting recovery from postoperative delirium.