Incidences, Characteristics, Management and Outcomes of Different Subtypes of Postoperative Delirium in Elderly Patients Admitted to the Surgical Intensive Care Unit: A Secondary Analysis of a Prospective Cohort Study

Objective: Postoperative delirium (POD) has three subtypes: hyperactive, hypoactive, and mixed, with each having distinct features and implications. This study aimed to determine the incidence, management, and clinical outcomes of each POD subtype in elderly patients admitted to the surgical intensive care unit (SICU) after surgery. Materials and Methods: This was a secondary analysis of a prospective cohort study of POD in the SICU. Patients aged ≥65 years admitted to the SICU and expected to stay in the SICU for >24 h were recruited. POD was screened using the Confusion Assessment Method for the ICU (CAM-ICU). Patients with positive CAM-ICU were defined as having POD and included in the analysis. The POD subtypes were categorized, pharmacological and nonpharmacological treatments were identified, and clinical outcomes were reported. Results: Of the 300 included patients, 117 developed POD, with 20 (17.1%) having hypoactive, 45 (38.5%) hyperactive, and 52 (44.4%) mixed. Medications were prescribed in 1 (5.0%), 34 (75.6%), and 35 (67.3 %) in patients with hypoactive, hyperactive, and mixed POD, respectively (P <0.001). Patients with hypoactive POD had the longest duration of delirium, longest length of stay in both the SICU and hospital, and highest hospital mortality. Multivariate regression analysis revealed that hypoactive POD was significantly associated with increased hospital mortality (odds ratio, 3.88; 95% confidence interval, 1.15–13.11). Conclusion: Different POD subtypes resulted in different outcomes. Although hypoactive POD had the lowest incidence, it carried the highest mortality risk.