Abstract Details

Title Delirium Shows Lower Mortality Than Other Encephalopathy Types in Critically Ill Patients: A Survival Analysis of 15,630 ICU Stays

Topic Neuro Trauma and Critical Care

Presentation(s) P6 - Poster Session 6 (5:00 PM-6:00 PM)

Poster/Presentation
Number 19-010

Objective To compare mortality across encephalopathy subtypes—delirium, toxic, metabolic, and unspecified—in ICU patients and assess independent predictors of survival using adjusted and subgroup analyses.
Additionally, to explore whether the lower mortality in delirium reflects its greater reversibility compared with other encephalopathy etiologies.

Background

Different encephalopathy types in the ICU may have distinct prognoses, but comparative outcomes data are limited. We hypothesized that encephalopathy etiology influences mortality risk in critically ill patients.

Design/Methods

Retrospective cohort study of 11,468 patients with encephalopathy across 15,630 ICU stays in MIMIC-IV. Patients were categorized into four encephalopathy types: delirium (32.4%), toxic (34.0%), metabolic (15.8%), and unspecified (17.9%). Primary outcome was all-cause mortality up to 1 year. We used Cox proportional hazards models adjusted for age, gender, severity, ICU type, and length of stay. Kaplan-Meier curves compared survival distributions. Subgroup analyses stratified outcomes by age, severity, and ICU type.

Results Overall mortality was 18.8% in-hospital, rising to 44.8% at 1 year. After adjustment, delirium showed a protective effect compared to unspecified encephalopathy (reference): hazard ratio 0.84 (95% CI 0.79-0.89, p<0.001), representing 16% lower mortality risk. Metabolic encephalopathy showed no significant difference: HR 1.05 (0.98-1.13, p=0.140). Toxic encephalopathy showed no significant difference: HR 0.98 (0.92-1.03, p=0.396). Unadjusted mortality rates were: delirium 49.2%, metabolic 59.1%, toxic 57.3%, unspecified 57.0%. The protective effect of delirium persisted across age groups, severity levels, and ICU types. Age (HR 1.01 per year, p<0.001) and high severity (HR 5.63, p<0.001) were the strongest mortality predictors.

Conclusions

Delirium is associated with 16% lower mortality risk compared to other encephalopathy types in ICU patients, even after adjusting for severity and other confounders. This suggests delirium may be more reversible than metabolic or toxic encephalopathy, with important implications for prognostication and treatment strategies.

KEYWORDS: delirium, encephalopathy, mortality, prognosis, critical care, survival analysis

Authors/Disclosures
Shankar Biswas, MD PRESENTER	Dr. Biswas has nothing to disclose.
Sindhu Vasireddy, MD	Dr. Vasireddy has nothing to disclose.
Elangovan Krishnan, MBBS, PhD, PGDHM, M Tech	Dr. Krishnan has nothing to disclose.
Riya Srivastava	Ms. Srivastava has nothing to disclose.
Jeimy M. Castellanos, MBBS	Dr. Castellanos has nothing to disclose.

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