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.