Simplifying Frailty Assessment in Kidney Transplant Patients: Introducing the Abridged Frailty Phenotype

Image of Human Kidneys by Unknown Author is licensed under Creative Commons BY
Image of Human Kidneys by Unknown Author is licensed under Creative Commons BY

It’s widely known that frailty is associated with poor outcomes in surgical patients including kidney transplant patients. National projections estimate that 16.4% of transplant candidates and 14.3% of recipients are frail (Haugen et al, 2020). Remarkably, transplant centers that measure frailty achieve better pre- and post-operative outcomes (Chen et al, 2022). However, frailty assessments aren’t consistently used at transplant centers for many reasons, with time constraints being a significant barrier (McAdams-DeMarco et al, 2020). Therefore, we sought to create a more condensed frailty assessment that does not compromise on discrimination of clinical outcomes.

In our recent study published in The Journals of Gerontology, we propose a new frailty assessment, the abridged frailty phenotype (Chen et al, 2023). The abridged physical frailty phenotype was developed by simplifying the five physical frailty phenotype components (Fried et al, 2001) in a two-center prospective cohort of 3,220 kidney transplant candidates (Table 1). We found that the physical frailty phenotype and abridged assessment identified 23.8% and 27.4% candidates as frail, respectively. The abridged frailty physical phenotype had substantial agreement (kappa = 0.69, 95% CI: 0.66–0.71) with the physical frailty phenotype and excellent discrimination of it (AUC = 0.861). Among a subset of 20 patients at evaluation, the abridged assessment took 5–7 minutes to complete. The physical frailty phenotype and abridged assessment had similar associations with waitlist mortality (subdistribution hazard ratio [SHR] = 1.62, 95% CI: 1.26–2.08 vs SHR = 1.70, 95% CI: 1.33–2.16) and comparable mortality discrimination, using Harrell’s C-statistic (p = .51).

The results of this study support the use of this novel, validated light-touch frailty phenotype in clinical settings. It offers a cost-effective, objective measure of frailty that is both easier and more efficient to use when compared to the original physical frailty phenotype. Importantly, it maintains high accuracy in identifying frail and non-frail patients. Therefore, transplant departments should consider utilizing the abridged assessment to evaluate frailty in patients when time is limited.

It’s important to note that our aim is not to add yet another frailty assessment to the existing arsenal (Buta et al, 2016). In 2018, the American Society of Transplantation concluded that “a standard, validated measure of frailty is yet to be established” for the field (Kobashigawa et al, 2019). We hope that the abridged physical frailty phenotype can fill this gap and become universally accepted across disciplines. Standardization is essential when we discuss frailty; we must ensure that we are all speaking the same language by using consistent tools for measurement.

In conclusion, the development of the abridged physical frailty phenotype represents a step forward in improving the care and outcomes of our patients. Its simplicity, efficiency and effectiveness make it a valuable addition to the toolkit of providers and researchers alike, paving the way for standardized frailty assessment in the future.

Table 1. Components of the original physical frailty phenotype (PFP) and the abridged physical frailty phenotype.

This work was supported by NIH grant R01AG055781 (PI: McAdams-DeMarco).  Dr. Quint was a visiting scholar at NYU Grossman School of Medicine while working on the publication.

Towards a self-reported assessment of physical frailty: updates and challenges

Physical frailty is commonly defined by the Physical Frailty Phenotype (Fried et al, 2001), which uses a combination of self-report and objective measures. Physical frailty is a powerful predictor of health outcomes, but it is rarely used outside of research settings because of challenges with implementation. In a busy clinical setting, performing repeated grip strength and timed walking tests is rarely feasible. Self-report questionnaires, in contrast, are easily administered both in the office and even at home for telemedicine visits. Currently, fully self-reported assessments, such as the FRAIL Scale, are not strongly correlated with the PFP (Aguayo et al, 2017).  We therefore set out to develop a self-reported tool that would correlate well with physical frailty, and thus be useful in settings with time and resource constraints.

In our recent study published in the BMC Geriatrics, we tested several possible self-reported frailty phenotypes which included different combinations of questions focused on slowness and weakness (Buta et al, 2022). When we substitute sets of 3 questions for each of the objective measures in the PFP there was substantial agreement between standard and self-reported measures of physical frailty for a 2-level model of frail/non-frail (Kappa=0.76– 0.78). We also found the highest sensitivity (86.4%) and negative predictive value (98.7%) for identifying frail older adults when comparing the standard PFP to a self-reported version that included these 3 slowness- and 3 weakness-related questions. The self-report tool took participants less than 5 minutes to complete.

Table of Physical Frailty Measures/ Criteria Assessed in this Study

We found only fair-to-moderate levels of agreement in a 3-level model that categorized participants as either frail, pre-frail or non-frail. Also, the generalizability of our findings may be limited by the study population of aging registry participants from the Baltimore area. Compared to US national demographics (US Census Bureau), our study population had a higher prevalence of participants who were female; African American; and had completed a bachelor’s degree or higher.

Clinician with hispanic female older adultOur results show the utility as well as the challenges of using self-reported questions to identify a frailty phenotype in clinic. Additional testing in general clinic populations should be done, with refinement of the questionnaire as needed, since a self-reported physical frailty measure with high agreement to the standard phenotype will be a valuable frailty screening assessment in both clinical and telehealth settings. To this end, we have recently published complementary work in a larger epidemiological study that highlights the importance of selecting viable self-report measures: common self-reported disability questions do not appear to serve as strong proxies for the physical frailty phenotype’s performance-based measures (Bandeen-Roche et al, 2023). Additional efforts to simplify the assessment of physical frailty are ongoing (Chen et al, 2023).

The results of this study suggest that a self-report assessment would be valuable as a screening tool if it has low rate of “false negatives”–that is we are unlikely to miss people who would be categorized as frail by the standard phenotype.  In order to optimize clinical intervention early in the course of physical frailty, a sensitive screening tool that is easy to administer followed by targeted objective tests to confirm frailty is an efficient strategy but depends on the effectiveness of the interventions. In Europe, a population wide, app-based frailty screening effort is underway that includes interventional targets following screening and comprehensive evaluation (Subra, 2012). It will be important in the future to follow up this research with high quality intervention studies.