Objective: To identify the prevalence of dementia among elderly surgical patients and to compare the postoperative
complications, length of hospital stays and mortalities.

Materials and Methods: Elderly surgical patients aged over 60 both in the surgical intensive care units (SICUs) and the general surgical wards were enrolled in the study, between March 2015 and July 2016. Dementia was assessed by using the Thai version of the Modified Informant Questionnaire on Cognitive Decline in the Elderly (Modified IQ CODE).

Results: Out of 427 participants, 169 (39.6%) were admitted to SICUs, while 258 (60.4%) were admitted to wards after their operations. The overall prevalence of dementia found in this study was 13.1%; the prevalence was 9.5% in the critically ill patients and 15.5% in the general surgical
patients. The participants with dementia were significantly older than the non- dementia patients (77.3+7.4 vs. 74.0+7.8 years, p = 0.003). The incidence of postoperative delirium was statistically significantly higher among those patients who had pre-operative dementia than those who had no dementia (46.4% vs. 16.7%, p<0.001). The adverse events, including hospital events, nosocomial infection rates, hospital mortalities, and hospital length of stay did not significantly differ between the dementia and non-dementia patients.

Conclusion: The prevalence of dementia among the elderly surgical patients was 13.1%, similar to the findings of other studies in the same population. The prevalence was higher among older patients, and the incidence of postoperative delirium was significantly higher for patients with pre-existing dementia.

Keywords: Dementia, Elderly surgical patients, Modified IQ CODE