Objective  To investigate the incidence of delirium after noncardiac surgery among elderly patients and explore the possible perioperative risk factors.

  Methods  In this cross-sectional study using cluster sampling, totally 718 patients aged 65 or older who had undergone elective noncardiac surgeries in our hospital from August to December 2006 were enrolled. Patients were interviewed at the day before surgery and an informed consent was obtained. The same interviewer evaluated the patients prospectively for delirium with the Confusion Assessment Method (CAM) on the preoperative day 1, postoperative day 1, day 2, and day 3. Other information including previous medical history, comorbidities, anesthetics, and perioperative medications were also recorded.

  Results  Delirium occurred in 80 patients (11.1%) at during the first three postoperative days, among whom transient symptoms were more frequent than continuous delirium status (68, 85% vs. 12, 15%). The Logistic stepwise regression analysis indicated that the perioperative risk factors of delirium included advanced age (OR:1.480, 95% CI:1.070-2.046), history of stroke (OR:2.862, 95% CI:1.432-5.720), use of meperidine (OR:3.196, 95% CI:1.574-6.488) or scopolamine (OR:2.537, 95% CI:1.523-4.227), hypotention during the operation (OR:1.780, 95% CI:1.070-2.960), long-duration operations (≥ 3 h) (OR:2.610, 95% CI:1.538-4.431), and ICU admission after surgeries (OR:2.187, 95% CI:1.077-4.442).

  Conclusions  Advanced age or previous history of stroke are the most important risk factors of postoperative delirium. The incidence of postoperative delirium may be decreased by avoiding other risk factors such as perioperative hypotension, usage of meperidine and scopolamine, and long-duration operation.