Background : During hospitalization older adults have a high risk of developing functional impairments unrelated to the reasons for their admission. This is termed hospital-associated disability (HAD). This systematic review aimed to assess the incidence of HAD in older adults admitted to acute care with two outcomes: firstly in at least one activity of daily living from a set of functional tasks (e.g., Katz Index) and secondly the incidence of functional decline in an individual functional task (e.g., bathing), and to identify any tools or functional tasks used to assess activities of daily living (ADL) in hospitalized older patients. Methods : A rapid systematic review was performed according to the recommendations of the Cochrane Rapid Reviews Methods Group and reported the data according the PRISMA statement. A literature search was performed in Medline (via Ovid), EMBASE, and Cochrane Central Register of Controlled Trials databases on 26 August 2021. Inclusion criteria: older adults (65+ years), assessment of individual items of activities of daily living at baseline and discharge. Exclusion criterion: studies investigating a specific condition that could affect functional decline and studies that primarily examined a population with cognitive impairment. The protocol was registered on OSF registries (https://osf.io/9jez4/) identifier: DOI 10.17605/OSF.IO/9JEZ4. Results: Ten studies were included in the final review. Incidence of HAD (overall score) was 37%(95% CI 0.300.43). Insufficient data prevented meta-analysis of the individual items. One study provided sufficient data to calculate incidence, with the following values for patients' self-reported dependencies: 32% for bathing, 27% for dressing, 27% for toileting, 30% for eating and 27% for transferring. The proxy reported the following values for patients' dependencies: 70% for bathing, 66% for dressing, 70% for toileting, 61% for eating and 59% for transferring. The review identified four assessment tools, two sets of tasks, and individual items assessing activities of daily living in such patients. Conclusions : Incidence of hospital-associated disability in older patients might be overestimated, due to the combination of disease-related disability and hospitalassociated disability. The tools used to assess these patients presented some limitations. These results should be interpreted with caution as only one study reported adequate information to assess the HAD incidence. At the item level, the latter was higher when disability was reported by the proxies than when it was reported by patients. This review highlights the lack of systematic reporting of data used to calculate HAD incidence. The methodological quality and the risk of bias in the included studies raised some concerns.