Long-term mortality of critically ill patients with cancer and delirium who survived to discharge: a retrospective cohort study

Purpose Delirium is common in critically ill patients and has been associated with lower short-term survival; however, its association with long-term survival has been scarcely evaluated and few studies have shown divergent results.Methods We conducted a retrospective cohort study of adult patients with cancer admitted to the intensive care unit (ICU) and discharged from hospital from January 2015 to December 2018. We considered delirium present if the Confusion Assessment Method for Intensive Care Unit (CAM-ICU) result was positive. We assessed the association between delirium during ICU stay and long-term mortality (up to three years after discharge). We also assessed the association between delirium type (hypoactive, hyperactive, and mixed) with long-term mortality.Results We included 3,079 patients. Of these, 430 (14%) were considered delirious at some point during their ICU stay. Delirium was associated with one-year mortality after hospital discharge (hazard ratio [HR], 1.58; 95% confidence interval [CI], 1.36 to 1.83) after adjustment for potential confounders, but not with one to three year-mortality (HR, 0.92; 95% CI, 0.61 to 1.39). Hypoactive and mixed delirium were associated with one-year mortality (HR, 1.77; 95% CI, 1.46 to 2.14 and HR, 1.56; 95% CI, 1.21 to 2.00, respectively), but none of the delirium motor types was associated with one to three-year mortality.Conclusions We observed that delirium during ICU stay was associated with increased one-year mortality, but was not with mortality after one year. This association was observed in hypoactive and mixed delirium types but not with hyperactive delirium.