Abstract
Older adults often experience rapid cognitive decline following hospitalization, especially those with severe illness and extended stays. Despite known links between increasing patient age and cognitive decline, 30% of older adults without major pre-existing conditions prior to medical admission show potential undiagnosed cognitive decline. This scoping review aims to map the prevalence, assessment methods, and associated factors of cognitive decline among hospitalized older adults. We conducted an exploratory review in accordance with the Joanna Briggs Institute (JBI) methodological framework and the PRISMA-ScR guidelines. The review targeted studies published between January 2018 and March 2025 in English or Spanish that reported in-hospital cognitive assessments in individuals aged 65 years and older. 'Cognitive decline' was operationally defined as performance below established cut-off scores on validated tools, such as the Mini-Mental State Examination (MMSE ≤ 23) or the Montreal Cognitive Assessment (MoCA < 26), administered during hospitalization. Databases consulted included PubMed, Web of Science, and ScienceDirect. A narrative synthesis was undertaken to organise findings by study design, cognitive instruments, prevalence rates, and associated factors. A total of thirty studies met the inclusion criteria. Most employed cross-sectional or prospective cohort designs, with wide variability in hospital settings, timing of assessments, and cognitive tools used. The reported prevalence of cognitive impairment ranged from 10% to 85%, depending on the assessment tools and population characteristics. MMSE and MoCA were the most frequently used tools. Associated factors included advanced age, comorbidities, pre-existing cognitive decline, and frailty. Methodological heterogeneity hindered meta-analysis, but it also revealed important limitations in the comparability of the studies. This review identifies substantial heterogeneity in the assessment and reporting of cognitive decline among hospitalized older adults. The findings highlight the need for standardized screening protocols and improved methodological consistency to optimise the detection, cross-study comparability, and clinical relevance of cognitive assessments in hospital settings.