Risk Factors and Incidence of Postoperative Delirium in Elderly Chinese Patients

Objectives: To investigate the incidence of postoperative delirium among elderly patients and to examine the interrelationship between basic vulnerability and precipitating factors for delirium. Design and Methods: This was a prospective cohort study. Data were collected in a tertiary medical center in Taipei, Taiwan. From the 1st to the 5th postoperative day, nurses assessed patients using a confusion-screening tool. Patients with signs of delirium were closely examined for changes in behavior and cognitive status and vital signs, and laboratory data were collected to further validate the organic etiology of delirium. Patients were finally diagnosed according to the DSM-IV criteria in consensus meetings. Subjects: Seven hundred and one elderly patients, that were admitted consecutively for elective orthopedic or urologic surgery, were enrolled in this study. All subjects met the following criteria: (1) 65 years of age or older; (2) able to communicate orally in Chinese, and (3) not unconscious, delirious, deaf, or aphasic upon admission. Results: The overall incidence of delirium among these subjects was 5.1%. Logistic regression analysis identified that older age and preexisting cognitive impairment were vulnerability factors, and that the use of psychoactive drugs was a precipitating factor for delirium. Patients with both basic vulnerability and the precipitating factor had a 56-fold increased probability of delirium (0.28 vs. 0.005 in comparison with those who did not exhibit these factors). Conclusion: Few risk factors of postoperative delirium in the older Chinese sample were identified. The only modifiable risk factor appears to be the use of psychoactive drugs.