Introduction: Delirium is an acute disturbance of consciousness and cognition that has been shown to be associated with poor outcomes, including increased mortality. We aimed to evaluate outcome after postoperative delirium in a cohort of surgical intensive care unit (SICU) patients.
Methods: This prospective study was conducted over a 10-month period in a SICU. Postoperative delirium was diagnosed in accordance with the Intensive Care Delirium Screening Checklist (ICDSC). The primary outcome was mortality at 6-month follow-up. Hospital mortality and becoming dependent were considered as secondary outcomes, on the basis of the evaluation of the patient's ability to undertake both personal and instrumental activities of daily living (ADL) before surgery and 6 months after discharge from the SICU. For each dichotomous outcome - hospital mortality, mortality at 6-month follow-up, and becoming dependent - a separate multiple logistic regression analysis was performed, which included delirium as an independent variable. Another outcome analyzed was changes in health-related quality of life, as determined using short-form 36 (SF-36), which was administered before and 6 months after discharge from the SICU. Additionally, for each SF-36 domain, a separate multiple linear regression model was used for each SF-36 domain, with changes in the SF-36 domain as a dependent variable and delirium as an independent variable.
Results: Of 775 SICU-admitted adults, 562 were enrolled in the study, of which 89 (16%) experienced postoperative delirium. Delirium was an independent risk factor for mortality at the 6-month follow-up (OR = 2.562, P <0.001) and also for hospital mortality (OR = 2.673, P <0.001). Delirium was also an independent risk factor for becoming dependent for personal ADL (P-ADL) after SICU discharge (OR = 2.188, P <0.046). Moreover, patients who experienced postoperative delirium showed a greater decline in SF-36 domains after discharge, particularly in physical function, vitality, and social function, as compared to patients without postoperative delirium.
Conclusions: Postoperative delirium was an independent risk factor for 6-month follow-up mortality, hospital mortality, and becoming independent in P-ADL after SICU discharge. It was also significantly associated with a worsening in the quality of life after surgery.