Frailty prevalence and clinical outcomes according to assessment tools: A systematic review

Frailty is a clinically recognizable state of increased vulnerability in older adults, marked by diminished physiological reserves before the onset of disability. Although multiple assessment tools exist, their inconsistent use across clinical specialties often leads to confusion and inappropriate decision-making. The objective is to describe the prevalence of frailty and its association with clinical outcomes according to different frailty assessment tools, in adults aged 65 years and older, across key clinical scenarios: acute myocardial infarction (AMI), chronic coronary artery disease (CCAD), heart failure (HF), diabetes mellitus (DM), transcatheter aortic valve implantation (TAVI), emergency departments (ED), intensive care units (ICU), and hip fracture. A systematic review with narrative synthesis was conducted in accordance with PRISMA 2020 guidelines. Searches were performed in PubMed covering the last 10 years. Included studies involved adults ≥65 years, used validated frailty tools, and reported outcomes such as mortality, rehospitalization, complications, or functional decline. A total of 626 articles were reviewed, of which 158 met the inclusion criteria. Prevalence varied according to the assessment tool used (4.4-90%) across all clinical settings. In AMI, the CFS (13 studies), Fried phenotype (9) and FI (8) were the most frequently used; the CFS was associated with 6-12 month mortality (HR 3.32; HR 1.90), readmissions and bleeding. In CCAD, the Fried phenotype and the CFS were associated with post-PCI mortality (HR 2.78 vs. 5.99). In HF, the Fried scale was predominant; frailty was associated with increased mortality (adjusted RR 2.04), readmissions and functional decline. In DM, Fried was the most commonly used tool. In TAVI, the CFS and Fried were associated with mortality, acute kidney injury and bleeding. In ED settings, the CFS and PRISMA-7 were associated with mortality, prolonged length of stay and readmissions. In ICU settings, the CFS was the most frequently used and was associated with mortality and complications. In hip fracture, the CFS and FI were associated with mortality, delirium and functional impairment. As conclusion frailty is highly prevalent in older adults across diverse clinical contexts, but its outcomes and prognostic value depend on the tool and definition used. Different frailty assessment tools appear to be associated with distinct clinical outcomes depending on the context in which they are applied. Meta-analyses should avoid merging studies that apply conceptually different frailty instruments.