[Prevalence, risk factors and characteristics of delirium in intensive care unit patients: a prospective...

To investigate the prevalence, risk factors, duration and outcome of delirium in intensive care unit (ICU) patients.

A prospective observational study was conducted for critically ill patients admitted to the department of critical care medicine, the Affiliated Hospital of Guizhou Medical University from September to November 2021. Delirium assessments were performed twice daily using the Richmond agitation-sedation scale (RASS) and confusion assessment method of ICU (CAM-ICU) for patients who met the inclusions and exclusion criteria. Patient's age, gender, body mass index (BMI), underlying disease, acute physiologic assessment and chronic health evaluation (APACHE) at ICU admission, sequential organ failure assessment (SOFA) at ICU admission, oxygenation index (PaO₂/FiO₂), diagnosis, type of delirium, duration of delirium, outcome, etc. were recorded. Patients were divided into delirium and non-delirium groups according to whether delirium occurred during the study period. The clinical characteristics of the patients in the two groups were compared, and risk factors for the development of delirium were screened using univariate analysis and multivariate Logistic regression analysis.

A total of 347 ICU patients were included, and delirium occurred in 57.6% (200/347) patients. The most common type was hypoactive delirium (73.0% of the total). Univariate analysis showed statistically significant differences in age, APACHE score and SOFA score at ICU admission, history of smoking, hypertension, history of cerebral infarction, immunosuppression, neurological disease, sepsis, shock, glucose (Glu), PaO₂/FiO₂ at ICU admission, length of ICU stay, and duration of mechanical ventilation between the two groups. Multivariate Logistic regression analysis showed that age [odds ratio (OR) = 1.045, 95% confidence interval (95%CI) was 1.027-1.063, P < 0.001], APACHE score at ICU admission (OR = 1.049, 95%CI was 1.008-1.091, P = 0.018), neurological disease (OR = 5.275, 95%CI was 1.825-15.248, P = 0.002), sepsis (OR = 1.941, 95%CI was 1.117-3.374, P = 0.019), and duration of mechanical ventilation (OR = 1.005, 95%CI was 1.001-1.009, P = 0.012) were all independent risk factors for the development of delirium in ICU patients. The median duration of delirium in ICU patients was 2 (1, 3) days. Delirium was still present in 52% patients when they discharged from the ICU.

The prevalence of delirium in ICU patients is over 50%, with hypoactive delirium being the most common. Age, APACHE score at ICU admission, neurological disease, sepsis and duration of mechanical ventilation were all independent risk factors for the development of delirium in ICU patients. More than half of patients with delirium were still delirious when they discharged from the ICU.