ICU Delirium Linked to Post-Discharge Change in Cancer Treatment and Higher Mortality Among Cancer Patients

This is a summarized version of the full in-depth article on Relias Media.

By Betty Tran, MD, MSc

Associate Professor of Medicine, Division of Pulmonary and Critical Care Medicine, Northwestern University Feinberg School of Medicine, Chicago

SYNOPSIS: In this single-center, retrospective cohort study, intensive care unit (ICU) delirium was associated with a higher rate of cancer treatment modification, only partly due to worsening performance status, after discharge and higher one-year mortality.

SOURCE: Vizzacchi BA, Dettino ALA, Besen BAMP, et al. Delirium during critical illness and subsequent change of treatment in patients with cancer: A mediation analysis. Crit Care Med 2024;52:102-111.

Study Overview

The study focused on patients admitted between January 2015 and December 2018 who had an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0-2, excluding those with ECOG PS of 3 or 4 (those with limited self-care or complete disability). The primary exposure was ICU delirium, assessed twice daily using the Confusion Assessment Method for the ICU (CAM-ICU). Primary and secondary outcomes included changes in planned cancer treatment post-hospitalization, functional dependence, resumption of cancer treatment at six months, and one-year mortality.

Patient Demographics and Clinical Characteristics

A total of 1,134 patients met the study criteria, with 189 (16.7%) experiencing delirium during their ICU stay. The majority of patients had metastatic solid tumors, commonly originating from breast, colorectal, or lung cancers, and most were admitted for sepsis (32.1%). Patients with delirium were generally older, more likely male, and had worse baseline performance status (PS 1 or 2). They also had higher Simplified Acute Physiology Score 3 (SAPS 3) scores and were more likely to require invasive mechanical ventilation, renal replacement therapy, and had extended ICU and hospital stays.

Primary and Secondary Outcomes

Change in Cancer Treatment

The primary outcome was a change in previously planned cancer treatment, assessed at the first outpatient visit after hospital discharge (median nine days post-discharge). Delirium in the ICU was significantly associated with treatment changes, with an adjusted odds ratio (OR) of 3.80 (95% CI, 2.72-5.35), suggesting that patients who experienced delirium were markedly more likely to discontinue or alter their cancer treatment post-ICU.

Functional Dependence and Mediation Analysis

Delirium was also associated with a higher likelihood of functional dependence after hospital discharge (OR, 7.29; 95% CI, 4.11-13.14). A mediation analysis explored whether functional dependence accounted for the association between ICU delirium and changes in cancer treatment. The analysis revealed that functional dependence explained only 33% of the effect, suggesting that other factors, potentially including cognitive decline and new or exacerbated comorbidities, also contributed to decisions to halt or modify cancer treatment.

Cancer Treatment Resumption and Mortality

At the six-month follow-up, 108 of the 147 patients who interrupted cancer treatment had resumed their regimen. The likelihood of resuming treatment did not significantly differ between those who had experienced delirium (75.7%) and those who had not (72.6%; P = 0.71). However, treatment discontinuation was associated with significantly higher one-year mortality, with an adjusted OR for death of 2.68 (95% CI, 2.01-3.60).

Commentary and Implications

This study underscores the critical role of ICU delirium as a determinant of adverse outcomes in cancer patients. The incidence of delirium was notably lower (16.7%) than in other ICU cohorts, potentially due to the study’s selective population and the center’s lack of a step-down unit, limiting patient variability. Another contributing factor may be the lower frequency of CAM-ICU assessments compared to other studies. Nonetheless, the study demonstrates a strong correlation between ICU delirium and detrimental effects on cancer treatment continuation, functional independence, and survival.

The mediation analysis suggests that the impact of delirium extends beyond physical dependence, likely involving cognitive decline, new comorbidities, and possibly altered patient or surrogate decision-making regarding treatment goals. Delirium may introduce lasting vulnerabilities, making patients less suitable for intensive cancer therapies. The findings point toward a need for interventions to address delirium risk and support post-discharge management strategies to mitigate its long-term effects.

Clinical Implications and Future Considerations

The study's outcomes stress the importance of delirium prevention and management in the ICU, especially for patients with active cancer treatments. Multidisciplinary discussions among oncologists, intensivists, and patients or their surrogates may be critical in assessing the impact of ICU delirium on treatment goals and quality of life post-discharge. Given the association between delirium and long-term functional and survival outcomes, there is a pressing need to prioritize interventions that reduce delirium incidence in ICU settings and integrate structured follow-up to reassess treatment feasibility in cancer survivors.

In conclusion, ICU delirium significantly affects the continuity and feasibility of cancer care in patients with active malignancies. Enhanced delirium prevention and management strategies could be pivotal in improving patient outcomes, supporting post-discharge functional recovery, and enabling more patients to resume their cancer treatment regimens.

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We discuss ICU delirium and post-discharge change in cancer treatment in more detail and include detailed charts and tables in our full write-up on Relias Media.

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