Korean J Psychosom Med.  2019 Dec;27(2):101-110. 10.22722/KJPM.2019.27.2.101.

A Study on Clinical Variables Contributing to Differentiation of Delirium and Non-Delirium Patients in the ICU

  • 1Department of Psychiatry and Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, Korea. empathy@yuhs.ac, ojuojuoju@yuhs.ac
  • 2Department of Psychiatry, Severance Hospital, Yonsei University Health System, Seoul, Korea.
  • 3Department of Psychiatry, Gangnam Severance Hospital, Yonsei University Health System, Seoul, Korea.
  • 4Deepmedi Research Institute of Technology, Deepmedi Inc., Seoul, Korea.


It is not clear which clinical variables are most closely associated with delirium in the Intensive Care Unit (ICU). By comparing clinical data of ICU delirium and non-delirium patients, we sought to identify variables that most effectively differentiate delirium from non-delirium.
Medical records of 6,386 ICU patients were reviewed. Random Subset Feature Selection and Principal Component Analysis were utilized to select a set of clinical variables with the highest discriminatory capacity. Statistical analyses were employed to determine the separation capacity of two models-one using just the selected few clinical variables and the other using all clinical variables associated with delirium.
There was a significant difference between delirium and non-delirium individuals across 32 clinical variables. Richmond Agitation Sedation Scale (RASS), urinary catheterization, vascular catheterization, Hamilton Anxiety Rating Scale (HAM-A), Blood urea nitrogen, and Acute Physiology and Chronic Health Examination II most effectively differentiated delirium from non-delirium. Multivariable logistic regression analysis showed that, with the exception of vascular catheterization, these clinical variables were independent risk factors associated with delirium. Separation capacity of the logistic regression model using just 6 clinical variables was measured with Receiver Operating Characteristic curve, with Area Under the Curve (AUC) of 0.818. Same analyses were performed using all 32 clinical variables;the AUC was 0.881, denoting a very high separation capacity.
The six aforementioned variables most effectively separate delirium from non-delirium. This highlights the importance of close monitoring of patients who received invasive medical procedures and were rated with very low RASS and HAM-A scores.


Delirium; Intensive care unit; Electronic medical record; Discriminatory analysis

MeSH Terms

Area Under Curve
Blood Urea Nitrogen
Electronic Health Records
Intensive Care Units
Logistic Models
Medical Records
Principal Component Analysis
Risk Factors
ROC Curve
Urinary Catheterization
Urinary Catheters
Vascular Access Devices
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