Background : In elderly patients admitted to an intensive care unit (ICU), delirium is a common disease and has a poor prognosis. However, early detection of delirium is difficult in elderly patients because most of them have different degrees of senile brain change and most delirium manifests as hypoactivity. To improve the prognosis of the ICU, it is important to identify risk factors for delirium and actively select high-risk patients for delirium.

Aims and objectives : To Identify risk factors for delirium and develop modeling using risk factors.

Method : This study was a multicenter prospective observation study performed on critically ill patients at four academic tertiary care hospitals in South Korea between June 2021 and December 2022.

Results : Of the 220 patients, 70 patients (31.8%) were diagnosed with delirium. The median age of these patients was 76 years and 51(72.9%) were male. Smoking history, ventilator use, psychologic history, and hemodialysis were statistically significant independent predictors of delirium in elderly patients. When developing modeling using risk factors, Model IV including smoking history, ventilator use, psychological history, and hemodialysis was superior to other models. The performance of Model IV was fair (AUC, 0.754; 95% CI, 0.686?0.822; P<0.001).

Conclusions : Risk factors for delirium in elderly patients admitted to the ICU were smoking history, ventilator use, psychological history, and hemodialysis. If ventilator and CRRT are applied to elderly smokers with a history of psychosis, active delirium screening is required to detect delirium. Additional studies involving multinational cohort are warranted.