Delirium and post-discharge dementia: results from a cohort of older adults without baseline cognitive impairment

Objectives to investigate the association between delirium occurrence in acutely ill older adults and incident dementia after hospital discharge. Methods retrospective cohort study examining acutely ill older adults aged +60 years and consecutively admitted to the geriatric ward of a tertiary university hospital from 2010 to 2016. Inclusion criteria were absence of baseline cognitive decline on admission and documented clinical follow-up of +12 months after discharge. Admission data were collected from our local database, including results from a standardized comprehensive geriatric assessment completed for every patient. Pre-existing cognitive decline was identified based on clinical history, CDR and IQCODE-16. Delirium was diagnosed using short-CAM criteria, while post-discharge dementia after 12 months was identified based on medical records’ review. We used competing-risk proportional-hazard models to explore the association between delirium and post-discharge dementia. Results we included 309 patients. Mean age was 78 years, and 186 (60%) were women. Delirium was detected in 66 (21%) cases. After a median follow-up of 24 months, 21 (32%) patients who had experienced delirium progressed with dementia, while only 38 (16%) of those without delirium had the same outcome (P = 0.003). After adjusting for possible confounders, delirium was independently associated with post-discharge dementia with a sub-hazard ratio of 1.94 (95%CI = 1.10–3.44; P = 0.022). Conclusion one in three acutely ill older adults who experienced delirium in the hospital developed post-discharge dementia during follow-up. Further understanding of delirium as an independent and potentially preventable risk factor for cognitive decline emphasizes the importance of systematic initiatives to fight it.