Frailty and hospital readmissions are two major problems for older people because of their impact on health, quality of life and healthcare systems. The aims of this study were to investigate the relationship between frailty and unplanned readmissions at 30, 90, 180 days and 1 year in hospitalised older people, and to identify the most relevant tools for assessing readmission risk in different clinical settings to facilitate systematic identification of this high-risk population by healthcare professionals.

This review was based on a systematic search of the MEDLINE, EMBASE and SCIENCEDIRECT databases for articles published between January 2011 and December 2021 that examined the association between frailty and unplanned readmission in hospitalised adults aged 65 years and over using identified validated tools.

44 eligible studies out of 1362 were included in a descriptive analysis. Sixteen countries were represented with older adults hospitalised in medical, surgical, post-acute care and rehabilitation, and emergency departments. Up to 84.5% of frail older adults had an unplanned readmission. Of the 21 tools identified, the Hospital Frailty Risk Score (HFRS), the Frailty Index (FI), its derivatives, the Clinical Frailty Scale (CFS) and the Fried criteria were the most widely used and relevant tools for identifying the association between frailty and unplanned readmission.

Frailty is widely associated with readmission risk in older adults. The HFRS, FI, CFS and Fried model appear to be the most commonly used tools to assess frailty and prevent unplanned readmissions.