Association of the overlap of cognitive impairment and depression with 6-month mortality in hospitalized older adults: results from the Re.Po.SI register

Background: When admitted to hospital for unplanned medical needs, the complexity of multiple conditions, including cognitive and mental health, might put older people at greater risk, affecting their survival. This study aimed to investigate the prevalence of cognitive impairment versus cognitive impairment with depression and their association with six-month mortality in older people after an unplanned hospital admission in Italy. Methods: In Re.Po.SI. a multi-centre study performed in Italy, standardized web-based case report forms were used to collect data on socio-demographic factors, clinical parameters, diagnoses, treatment history and at discharge, clinical events during hospitalization, and outcome data was collected. A comprehensive geriatric assessment was conducted using Cumulative Illness Rating Scale (CIRS), Geriatric Depression Scale (GDS-4), Barthel Index, and Short Blessed Test (SBT). To explore the interrelationship between depression and cognitive impairment, a variable categorized the study population into four mutually exclusive groups. This variable assessed the association between its categories and six-month mortality in a Cox multivariate analysis. Results: One thousand nine hundred fifty six participants were included, with a median age of 80 years (IQR: 73–85). Those who died within six months were likely to be older (82 vs. 79 years), male (56.2% vs. 47.2%), had moderately reduced ability to perform daily activities (82.0 vs. 93.0), exhibited greater illness severity (CIRS-IS: 1.8 vs. 1.6), had more chronically prescribed medications (6.0 vs. 5.0), and had a worse SBT score (10.0 vs. 7.0). When stratified based on cognitive impairment and depression, one-third had neither condition (33.2%), 21.9% had depression, 20.7% had a cognitive impairment, and 24.3% had both conditions. Six-month mortality was higher among people with cognitive impairment only (33.2%) followed by those with both conditions (28.8%), and depression only (22.7%). The unadjusted semi-parametric survival analysis revealed that the hazard ratio (HR) for people with cognitive impairment only was 2.08, for those with both conditions HR was 1.75, and for people with depression only HR was 1.30. Conclusion: While depression alone may contribute to mortality risk, cognitive impairment appears to play a more substantial role in increasing the risk of dying within 6 month from an acute hospitalization. Further research is needed to confirm these finding.