Impact of Delirium Onset and Duration on Mortality in Patients With Cancer Admitted to the ICU

Background Little is known on the effects of delirium onset and duration on outcome in critically ill patients with cancer. Objectives To determine the impact of delirium onset and duration on intensive care unit (ICU) and hospital mortality and length of stay (LOS) in patients with cancer. Methods Of the 915 ICU patients admitted in 2018, 371 were included for analysis after excluding for terminal disease, <24-h ICU stay, lack of active cancer and delirium. Delirium was defined as early if onset was within 2 days of ICU admission, late if onset was on day 3 or later, short if duration was 2 days or less, and long if duration was 3 days or longer. Patients were placed into 4 combination groups: early-short, early-long, late-short, and late-long delirium. Multivariate analysis controlling for sex, age, metastatic disease, and predelirium hospital LOS was performed to determine ICU and hospital mortality and LOS. Exploratory analysis of long-term survival was also performed. Restricted cubic splines were performed to confirm the use of 2 days to distinguish between early versus late onset and short versus long duration. Results A total of 32.9% (n = 122) patients had early-short, 39.1% (n = 145) early-long, 16.2% (n = 60) late-short, and 11.9% (n = 44) late-long delirium. Late-long delirium was independently associated with increased ICU (OR 4.45, CI 1.92-10.30; P < .001) and hospital (OR 2.91, CI 1.37-6.19; P = .005) mortality and longer ICU (OR 1.97, CI 1.58-2.47; P < .001) LOS compared to early-short delirium. Early delirium had better overall survival at 18 months than late delirium. Long-term survival further improved when delirium duration was 2 days or less. Prediction heatmaps confirm the use of a 2-day cutoff. Conclusion Late delirium, especially with long duration, significantly worsens outcome in ICU patients with cancer and should be considered a harbinger of poor overall condition.