Frequency and Risk Factors of Subsyndromal Delirium in the Intensive Care Units: A Prospective Cohort Study

Subsyndromal delirium (SSD) is a common neuropsychiatric disorder among the intensive care units (ICU) patients. SSD is characterized by the presence of delirium symptoms but it does not meet the diagnostic criteria of delirium, resulting in poor patient prognosis.

The aim of this study was to explore the prevalence and risk factors for SSD among adult patients admitted to the ICU of XXX hospital in Southwest China.

The study participants comprised 309 patients referred to the ICU in XXX hospital between 10th August 2021 and 5th June 2022. Demographic information, medical history, and other patient information were recorded. ICDSC assessment, physical examination and laboratory tests were performed on enrolled patients. Cognitive evaluation was conducted using the MMSE method.

The results showed that out the 309 patients, 99 had possible SSD (prevalence of 32.0%), with 55 SSD1 cases (ICDSC score of 1, 17.8% prevalence), 29 SSD2 cases (ICDSC score of 2, 9.4% prevalence) and 15 SSD3 cases (ICDSC score of 3, 4.9% prevalence). Previous history of mental illness (OR, 3.741; 95% CI, 1.136-12.324; P <0.05), auxiliary ventilation (OR, 3.364; 95% CI, 1.448-7.813; P <0.01), hemodialysis (OR, 11.369; 95% CI, 1.245-103.840; P <0.05), MMSE score (OR, 0.845; 95% CI, 0.789-0.904; P <0.001) and a temperature ≥ 37.5 °C (OR, 3.686; 95% CI, 1.404-9.732; P <0.01) were independent risk factors for occurrence of SSD among ICU patients.

Approximately one-third of the patients in the intensive care unit had high risk of SSD. Nursing staff should pay attention to management of the high-risk patients to prevent SSD from progressing delirium to improve patient prognosis.