Objective To investigate the current status of the occurrence of subdelirium syndrome (SSD） in mechanically ventilated patients and its risk factors.

Methods A total of 279 patients with mechanical ventilation admitted to the ICU of a tertiary hospital in Anhui Province in 2023 were selected as the research objects by the convenience sampling method, and the confusion assessment method for the ICU was used. The patients were divided into the SSD group and non-SSD group. Univariate and binary logistic regression were used to analyze the risk factors for the occurrence of SSD in ICU patients with mechanical ventilation, and the ROC curve was used to analyze the predictive efficacy of each risk factor for the occurrence of SSD.

Results Among 279 patients with mechanical ventilation, 228 cases (81.72%） developed SSD, 180 cases (78.94%） developed SSD before 3 days of mechanical ventilation, and 34 patients with SSD experienced recurrence. Binary logistic regression analysis showed that the age, APACHE-II score, CPOT score, mechanical ventilation time, C-reactive protein and systolic blood pressure were the independent risk factors for SSD in ICU patients with mechanical ventilation. The results of ROC curve analysis showed that the age, APACHE-II score, mechanical ventilation time, area under the curve of C-reactive protein and 95%CI were 0.733 (95%CI: 0.658–0.807）, 0.795 (95%CI: 0.737–0.853）, 0.797 (95%CI: 0.734–0.860）, 0.589 (95%CI: 0.516–0.662）, respectively (P ＜ 0.01）.

Conclusions The incidence of SSD in ICU patients with mechanical ventilation is relatively high. The incidence is high within 4 days of mechanical ventilation, and recurrence may occur. The age, APACHE-II score, CPOT score, mechanical ventilation time, systolic blood pressure and C-reactive protein are the independent risk factors for the occurrence of SSD, and the age, APACHE-II score and CPOT score have good predictive efficacy.