Delirium Is a Robust Predictor of Morbidity and Mortality Among Critically Ill Patients Treated in the Cardiac Intensive Care Unit

Eric Pauley,MD; Anton Lishmanov,MD, PhD; Sara Schumann, RN; Gary J. Gala,MD; Sean van Diepen,MD, MSc; Jason N. Katz, MD, MHS


Am Heart J. 2015;170(1):79-86. 

In This Article

Abstract and Introduction


Background Delirium is common in the medical and surgical intensive care unit (ICU), and its association with morbidity and mortality is well described. Despite emerging data, which have highlighted a growing critical care burden in the contemporary cardiac ICU (CICU), much less is known about delirium in this specialized setting.

Methods and results Records for consecutive CICU patients aged ≥18 years who were admitted to our academic, tertiary care institution from December 2012 to March 2014 for a primary cardiovascular diagnosis were reviewed. Only those with a documented Confusion Assessment Method for ICU score were included in the final analysis. Baseline characteristics, resource use, and outcomes were collected. Disease severity was assessed using the modified Acute Physiology and Chronic Health Evaluation II score and the Simplified Acute Physiology Score II. Multivariable logistic and linear regression models were constructed to evaluate the association between CICU delirium, length of stay, and death.

Among 590 patients included, the prevalence of CICU delirium was 20.3%. Delirious patients were older, had greater disease severity, required longer ICU stays (5 vs 2 days; P < .001), and had higher mortality (27% vs 3%; P < .001). In the adjusted setting, delirium remained strongly associated with both increased mortality (P < .001) and length of stay (P = .001).

Conclusions In those with cardiac critical illness, delirium is common and associated with worse survival and greater resource consumption. Future study is needed to validate these findings and to develop effective strategies for the early identification and treatment of the delirious CICU patient.


Delirium is a disturbance of consciousness and cognition characterized by attention difficulties and perceptual disturbances, which can develop over hours to days.[1] Although it was previously considered an expected sequelae of critical illness, it is now a well-recognized adverse prognostic marker among intensive care unit (ICU) cohorts. The strong associations between delirium and morbidity, mortality, and health care costs have recently led to its more formal classification as a type of target organ injury in the critical care setting.[2–6]

With a prevalence as high as 80% among mechanically ventilated patients, delirium is quite common.[4,7] In noncardiovascular critical care, where the epidemiology has been well delineated, investigative attention has already shifted toward the development of methods for early detection, risk factor assessment, and the creation of targeted intervention strategies aimed at attenuating the untoward consequences of this disease process. It has even been suggested that delirium should be considered a preventable condition in the ICU and, hence might perform well as a reportable quality metric.[8]

Although extensively studied in medical and even surgical critical care populations, much less is known about delirium and its impact on the cardiac ICU (CICU). Coinciding with emerging evidence supporting the increased burden of critical illness in these specialized units,[9] delirium has recently been recognized as a prevalent comorbid condition among groups of cardiac critical care patients.[10–12] The current literature, however, has been limited by small sample sizes, single cardiac diagnoses, or mixed medical-surgical populations. We therefore sought to assess not only the prevalence of delirium among critically ill cardiovascular individuals but also to evaluate the prognostic significance of delirium in the CICU.