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Delirium risk factors identified in ICU cancer patients



Hematology-oncology patients who receive treatment in the intensive care unit often develop delirium, and according to new findings, mechanical ventilation, high-dose corticosteroid use, and brain metastases were identified as independent risk factors.

Roughly half of all hematology-oncology patients who were admitted to the ICU experienced delirium, explained lead author Rachel Klosko, PharmD, PGY-2 cardiology pharmacy resident at the Ohio State University, Columbus.

“Delirium was associated with increased mortality, an increase in hospital length of stay, and increased length of stay in the ICU,” she said.

Dr. Klosko presented the study results at the at the Critical Care Congress sponsored by the Society of Critical Care Medicine (SCCM), which was held virtually this year.

Delirium is an acute and fluctuating disturbance of consciousness and cognition and fluctuates in severity. Critically ill patients are subject to numerous risk factors for delirium. “It can occur in independently of any known neurological disorder,” said Dr. Klosko, adding that its occurrence has been associated with poorer outcomes in ICU patients.

In this study, Dr. Klosko and colleagues sought to determine the incidence of delirium in cancer patients who were admitted to the ICU, as well as identify the associated risk factors and recognize potential consequences of the development of delirium in this patient population.

They conducted a single center, retrospective, cohort study that evaluated patients between the ages of 18 and 89 years who were admitted to the hematology-oncology medical or surgical ICU between July 1, 2018, and June 30, 2019.

The study’s primary endpoint was the incidence of delirium within 7 days of ICU admission, defined as two positive Confusion Assessment Method for the ICU (CAM-ICU) assessments within 24 hours. Patients identified with delirium were compared to those without it, for the evaluation of secondary endpoints that included hospital mortality and ICU and hospital length of stay. The researchers also sought to identify independent risk factors for delirium in this population.

A total of 244 patients were included in the final analysis. Of this group, 125 (51.2%) experienced delirium during their stay in the ICU, and 119 (48.8%) did not.

Mortality in the delirium group was significantly higher at 32.8% vs. 15.1% (P = .001). In addition, the delirium group was associated with significantly higher ICU length of stay (6 days vs. 3 days, P < .001) and hospital length of stay (21 days vs. 12 days, P < .001).

“When comparing the baseline characteristics between the two groups, the delirium group had a longer hospital length prior to ICU admission, a higher SOFA score, a higher rate of brain metastases, a higher rate of shock, and higher receipt of high-dose steroids, benzodiazepines, and immunotherapy,” said Dr. Klosko.

After multivariable regression, four variables were included in the final model. Among patients with delirium, the SOFA score increased by 25% (odds ratio[OR] 1.25, P < .001), while the odds of delirium were almost four times higher among those treated with high-dose corticosteroids (OR 3.79, P = .004). Delirium was also eight times higher (OR 8.48, P < .001) among those who received mechanical ventilation and five times higher in (OR 5.38, P = .015) in patients with brain metastases.

Dr. Klosko noted that the main limitations for this study were that it was a single center retrospective analysis, and that patients were reviewed within the first 7 days of ICU admission. “This potentially missed patients who developed delirium outside of this time frame,” she said. In addition, “too few patients received high-dose benzodiazepines,” and “none of the patients received continuous neuromuscular blockade.”

However, in “contrast to these limitations, this is the largest study to date that has analyzed delirium in this population,” Dr. Klosko said.

Commenting on the study, Brenda Pun, DNP, RN, director of data quality at the Vanderbilt Critical Illness, Brain Dysfunction, and Survivorship Center, Nashville, Tenn., pointed out that the goal of this study was to describe delirium in this specific population. “But I will take a step backward and say that they are just confirming that these patients look like other ICU patients in many regards,” she said.

Brenda Pun, DNP, RN, Director of Data Quality at the Vanderbilt Critical Illness, Brain Dysfunction, and Survivorship (CIBS) Center, Nashville, Tenn.

Dr. Brenda Pun

She explained that the sicker patients are, the higher the rates of delirium. “We have implemented strategies to lower these rates, and they have improved,” Dr. Pun said. “Ten years ago, I would say that 80% of patients who were on a ventilator would have delirium but now the rates are around 50% and that’s what we are typically seeing now.”

Dr. Pun emphasized that this study shows that delirium is like the “canary in the coal mine” or a red flag. “It’s a sign that something is wrong and that we need to pay attention, because the patient’s outcome may be worse,” she said. “So this is saying that we need to see if there is something that can be changed or modified to decrease the incidence of delirium—these are important questions.”

There was no outside sponsor. The authors had no disclosures. Dr. Pun has no disclosures.

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