Impact of delirium subtypes on survival in older adults hospitalised for acute heart failure: a prospective study in an acute geriatric unit

Purpose: Delirium is a common complication in older adults hospitalised for acute heart failure (AHF), but its incidence, subtypes, and short-term outcomes remain poorly characterised in the very old population. This study aimed to determine the prevalence and incidence of delirium in patients admitted to an acute geriatric unit (AGU) with AHF, describe its subtypes, and assess their impact on 90-day post-discharge survival. Methods: This prospective observational study included older adults hospitalised for AHF in an AGU between April 2022 and November 2024. Delirium was assessed using the 4AT and DSM-5 criteria and categorised as prevalent (on admission) or incident (during hospitalisation). Delirium psychomotor subtypes were classified as hyperactive, hypoactive, or mixed. Sociodemographic, clinical, and follow-up data were collected. Ninety-day survival was evaluated using Kaplan-Meier curves and Cox regression models. Results: Among 399 patients (median age 87.4 years, 52% female), 132 (33%) experienced delirium, with 13.8% classified as prevalent and 19.2% as incident cases. Among those with delirium, 48% presented with the hyperactive, 31% with hypoactive, and 21% with the mixed subtype. In multivariable regression analysis, adjusted for relevant covariates, the hypoactive (adjusted HR 2.03, 95% CI 1.13-3.64) and mixed (adjusted HR 2.28, 95% CI 1.18-4.43) subtypes-but not the hyperactive subtype-were independently associated with an increased risk of death. Conclusions: Delirium is common in very old patients hospitalised for AHF. Our findings indicate that the hypoactive and mixed subtypes are independently associated with poor 90-day post-discharge survival, highlighting the importance of their active identification and management.