Poor outcomes of delirium in the intensive care units are amplified by increasing age: A retrospective cohort study.

Background: Delirium in patients in intensive care units (ICUs) is an acute disturbance and fluctuation of cognition and consciousness. Though increasing age has been found to be related to ICU delirium, there is limited evidence of the effect of age on delirium outcomes. The aim of this study is to investigate the relationship between age categories and outcomes among ICU delirium patients.

Methods: Data were extracted from the electronic ICU (eICU) Collaborative Research Database with records from 3,931 patients with delirium. Patients were classified into non-aged (<65 years), young-old (65-74 years), middle-old (75-84 years), and very-old (≥85 years) groups. A Cox regression model was built to examine the role of age in death in ICU and in hospital after controlling covariates.

Results: The sample included 1,667 (42.4%) non-aged, 891 (22.7%) young-old, 848 (21.6%) middle-old, and 525 (13.3%) very-old patients. The ICU mortality rate was 8.3% and the hospital mortality rate was 15.4%. Compared with the non-aged group, the elderly patients (≥65 yeras) had higher mortality at ICU discharge ( =13.726, =0.001) and hospital discharge ( =56.347, <0.001). The Cox regression analysis showed that age was an independent risk factor for death at ICU discharge (hazard ratio []=1.502, 1.675, 1.840, 95% confidence interval [] 1.138-1.983, 1.250-2.244, 1.260-2.687; =0.004, 0.001, 0.002 for the young-, middle- and very-old group, respectively) as well as death at hospital discharge (=1.801, 2.036, 2.642, 95% 1.454-2.230, 1.638-2.530, 2.047-3.409; all <0.001).

Conclusions: The risks of death in the ICU and hospital increase with age among delirious patients.