Relationship Between Intensive Care Unit Delirium Severity and 2-Year Mortality and Health Care Utilization

Am J Crit Care. 2020 Jul 1;29(4):311-317. doi: 10.4037/ajcc2020498.


Background: Critical care patients with delirium are at an increased risk of functional decline and mortality long term.

Objective: To determine the relationship between delirium severity in the intensive care unit and mortality and acute health care utilization within 2 years after hospital discharge.

Methods: A secondary data analysis of the Pharmacological Management of Delirium and Deprescribe randomized controlled trials. Patients were assessed twice daily for delirium or coma using the Richmond Agitation-Sedation Scale and the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Delirium severity was measured using the CAM-ICU-7. Mean delirium severity (from time of randomization to discharge) was categorized as rapidly resolving, mild to moderate, or severe. Cox proportional hazards regression was used to model time to death, first emergency department visit, and rehospitalization. Analyses were adjusted for age, sex, race, Charlson Comorbidity Index, Acute Physiology and Chronic Health Evaluation II score, discharge location, diagnosis, and intensive care unit type.

Results: Of 434 patients, those with severe delirium had higher mortality risk than those with rapidly resolving delirium (hazard ratio 2.21; 95% CI, 1.35-3.61). Those with 5 or more days of delirium or coma had higher mortality risk than those with less than 5 days (hazard ratio 1.52; 95% CI, 1.07-2.17). Delirium severity and number of days of delirium or coma were not associated with time to emergency department visits and rehospitalizations.

Conclusion: Increased delirium severity and days of delirium or coma are associated with higher mortality risk 2 years after discharge.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Comorbidity
  • Critical Illness
  • Delirium / mortality*
  • Delirium / pathology*
  • Emergency Service, Hospital / statistics & numerical data
  • Female
  • Humans
  • Intensive Care Units / statistics & numerical data*
  • Male
  • Middle Aged
  • Patient Acceptance of Health Care / statistics & numerical data*
  • Patient Readmission / statistics & numerical data
  • Proportional Hazards Models
  • Risk Factors
  • Severity of Illness Index