Frailty in kidney transplant candidates: a comparison between physical frailty phenotype and FRAIL scales

Frailty Assessment Tools in Chronic Kidney Disease: A Systematic Review and Meta-analysis

Rationale & Objective

Frailty represents a loss of physiologic reserve across multiple biological systems, confers a higher risk of adverse health outcomes, and is highly prevalent among people with chronic kidney disease (CKD). We evaluated the measurement properties of frailty tools used in CKD and summarized the association of frailty with death and hospitalization.

Study Design

Systematic review and meta-analysis.

Setting & Study Populations

Studies assessing multidimensional frailty tools in adults at any stage of CKD and evaluating a measurement property of interest as per the Consensus-based Standards for the Selection of Health Measurement Instruments taxonomy.

Selection Criteria for Studies

Observational studies and randomized trials.

Data Extraction

Risk and precision measurements; measurement properties.

Analytical Approach

The Comprehensive Geriatric Assessment was the clinical standard for frailty identification. We pooled data using random effects models or summarized with narrative synthesis when data were too heterogenous to pool.

Results

We included 105 studies with data for at least one of the following: discriminative (n = 84; 80%), convergent (n = 20; 19%), and criterion validity (n = 2; 2%); responsiveness (n = 9; 9%) and reliability (n = 1; 0.1%). For the Fried Frailty Phenotype (FFP), the pooled adjusted HR (aHR) for mortality was 2.01 (95% confidence intervals [CI], 1.35-2.98; P = 0.001; I 2 = 58%) and 1.89 (95% CI, 1.25-2.85; P = 0.002; I 2 = 0%) for hospitalization in kidney failure (KF) populations. The pooled aHR for the Clinical Frailty Scale for mortality in pre-frail versus non-frail was 1.75 (95% CI, 1.17-2.60; I 2 = 26%) and 2.20 (95% CI, 1.00-4.80; I 2 = 66%) in frail versus non-frail. The Fatigue, Resistance, Ambulation, Illness, and Loss of weight scale showed consistent discriminative validity for higher mortality in non-dialysis CKD. The modified FFP (self-reported) showed acceptable discriminative validity and agreement with the FFP in patients with KF. In CKD and KF populations, agreement between clinicians' subjective impression of frailty and frailty tools was low.

Limitations

Few studies compared the accuracy of frailty tools to the Comprehensive Geriatric Assessment. Only 1 study reported reliability. Studies were of overall low-moderate quality.

Conclusions

The FFP and Clinical Frailty Scale showed acceptable discriminant validity for clinical outcomes, and the modified FFP is an alternative tool to use if direct measurements are not feasible. The evidence does not support the use of clinicians' subjective impression to identify frailty.

Unmet Questions About Frailty in Kidney Transplant Candidates

Frailty occurs frequently among patients with advanced chronic kidney disease, especially among women. Assessing frailty in kidney transplant (KT) candidates is crucial for informing them about associated risks. However, there is poor agreement between frailty scales and research on their correlation with transplant outcomes. Being prefrail significantly impacts both graft and patient survival, often beginning with just 1 Fried criterion. Rather than viewing frailty as a categorical state, it should be regarded as a spectrum ranging from 1 to 5 criteria, with the risk of adverse outcomes escalating as frailty worsens. Frailty status fluctuates during the waiting period for KT; hence, a 1-time frailty evaluation is insufficient to determine risks and implement strategies for improving functional status. Further research should investigate the components of frailty that most frequently change during this waiting period and establish strategies to prevent or reverse frailty. Although careful evaluation of frail KT candidates is necessary to prevent early complications and mortality, exclusion based solely on a frailty score is unwarranted. Instead, efforts should focus on timely interventions to enhance their condition before transplantation. Although evidence is limited, exercise programs appear feasible and yield positive results. A pretransplant clinical framework encompassing multimodal prehabilitation-comprising physical therapy, nutritional measures, and psychological support-during the waiting list period may help alleviate the effects of frailty and poor fitness after KT, ultimately improving key outcomes. Despite logistical challenges, there is a pressing need for interventional trials in this area.

Renal transplantation in older adults: retrospective cohort study to examine the impact of the new 2019 kidney offering scheme on older adult transplant recipients

INTRODUCTION

In 2019, a new kidney offering scheme was launched in the United Kingdom, aiming to better match estimated patient survival and graft life expectancy. The scheme's impact on older patients undergoing kidney transplantation (KT) is unknown. This study aims to compare the outcomes of older adult KT recipients before and after introduction of the 2019 scheme.

METHODS

A retrospective observational cohort study of older adults who underwent KT was undertaken. Group 1 were transplanted between 1 September 2017 and 31 August 2019 (2006 allocation scheme) and group 2 between 1 September 2019 and 31 August 2021 (2019 offering scheme). An older adult was any person ≥60 years old at the time of KT. Univariable binary logistic regression analysis was performed to determine odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

There were 107 older adult deceased donor KT recipients, 62 from group 1 and 45 from group 2. Median age at transplantation was 68 (interquartile range [IQR] 62-71) and 67 (IQR 64-73) years, respectively. Univariable analysis showed that re-intervention (OR 6.486, 95% CI 1.306-32.216, p = 0.022) and critical care admission (OR 5.619, 95% CI 1.448-21.812, p = 0.013) were significantly more likely in group 2. Group 2 recipients were significantly more likely to have a level 4 human leucocyte antigen (HLA) mismatch (OR 4.667, 95% CI 1.640-13.275, p = 0.004) and to have undergone previous KT (OR 4.691, 95% CI 1.385-15.893, p = 0.013).

CONCLUSIONS

The introduction of the 2019 offering scheme was associated with re-intervention and critical care admission for older KT recipients. We also observed less-favourable HLA matches but more KT in difficult-to-match groups.

Frailty in the context of kidney transplantation

Frailty, defined as an inappropriate response to stressful situations due to the loss of physiological reserve, was initially described in the elderly population, but is currently being identified in younger populations with chronic diseases, such as chronic kidney disease. It is estimated that about 20% of patients are frail at the time of kidney transplantation (KT), and there is great interest in its potential predictive value for unfavorable outcomes. A significant body of evidence has been generated; however, several areas still remain to be further explored. The pathogenesis is poorly understood and limited to the extrapolation of findings from other populations. Most studies are observational, involving patients on the waiting list or post-KT, and there is a scarcity of data on long-term evolution and possible interventions. We reviewed studies, including those with Brazilian populations, assessing frailty in the pre- and post-KT phases, exploring pathophysiology, associated factors, diagnostic challenges, and associated outcomes, in an attempt to provide a basis for future interventions.

Latest advances in frailty in kidney transplantation: A narrative review

Frailty is a clinical syndrome that is characterised by decline in multiple systems with associated decreased physiological reserve and ability to respond to stressor events. It is associated with greater healthcare burden. It is common in patients with end-stage renal disease (ESRD). Kidney transplantation is considered the optimal form of renal replacement therapy for suitable patients with ESRD. However, surgery and immunosuppression are physiological stresses that can disproportionately affect frail individuals. Frailty is emerging as a potentially important risk factor in patients waitlisted for kidney transplantation. Most of the published research to date in this area comes from a single transplant centre in the USA. Frailty, as measured using the Physical Frailty Phenotype (FP), is prevalent in waitlisted patients and has been associated with early hospital re-admission, prolonged length of stay, delayed graft function and increased mortality after kidney transplantation. However, although kidney transplantation is a substantial physiological stress to a patient's reserve, by restoring kidney function, kidney transplantation has also been shown to improve a patient's frailty status. The FP is the most studied tool in patients waitlisted for transplantation, but it has not been able to distinguish those whose frailty is improved by kidney transplantation. In summary, there remain significant gaps in knowledge and uncertainties as to how to effectively use existing frailty measures to inform decision-making around kidney transplantation. Further research is needed to address these important gaps in the literature.

Frailty and solid-organ transplant candidates: a scoping review

BACKGROUND

There is currently no consensus as to a standardized tool for frailty measurement in any patient population. In the solid-organ transplantation population, routinely identifying and quantifying frailty in potential transplant candidates would support patients and the multidisciplinary team to make well-informed, individualized, management decisions. The aim of this scoping review was to synthesise the literature regarding frailty measurement in solid-organ transplant (SOT) candidates.

METHODS

A search of four databases (Cochrane, Pubmed, EMBASE and CINAHL) yielded 3124 studies. 101 studies (including heart, kidney, liver, and lung transplant candidate populations) met the inclusion criteria.

RESULTS

We found that studies used a wide range of frailty tools (N = 22), including four 'established' frailty tools. The most commonly used tools were the Fried Frailty Phenotype and the Liver Frailty Index. Frailty prevalence estimates for this middle-aged, predominantly male, population varied between 2.7% and 100%. In the SOT candidate population, frailty was found to be associated with a range of adverse outcomes, with most evidence for increased mortality (including post-transplant and wait-list mortality), post-operative complications and prolonged hospitalisation. There is currently insufficient data to compare the predictive validity of frailty tools in the SOT population.

CONCLUSION

Overall, there is great variability in the approach to frailty measurement in this population. Preferably, a validated frailty measurement tool would be incorporated into SOT eligibility assessments internationally with a view to facilitating comparisons between patient sub-groups and national and international transplant services with the ultimate goal of improved patient care.

Increased mortality after kidney transplantation in mildly frail recipients

Background

Physical Frailty Phenotype (PFP) is the most used frailty instrument among kidney transplant recipients, classifying patients as pre-frail if they have 1-2 criteria and as frail if they have ≥3. However, different definitions of robustness have been used among renal patients, including only those who have 0 criteria, or those with 0-1 criteria. Our aim was to determine the impact of one PFP criterion on transplant outcomes.

Methods

We undertook a retrospective study of 296 kidney transplant recipients who had been evaluated for frailty by PFP at the time of evaluating for transplantation.

Results

Only 30.4% of patients had 0 criteria, and an additional 42.9% showed one PFP criterion. As PFP score increased, a higher percentage of women and cerebrovascular disease were found. Recipients with 0-1 criteria had lower 1-year mortality after transplant than those with ≥2 (1.8% vs 10.1%), but this difference was already present when we only considered those who scored 0 (mortality 1.1%) and 1 (mortality 2.4%) separately. The multivariable analysis confirmed that one PFP criterion was associated to a higher risk of patient death after kidney transplantation [hazard ratio 3.52 (95% confidence interval 1.03-15.9)].

Conclusions

Listed kidney transplant candidates frequently show only one PFP frailty criterion. This has an independent impact on patient survival after transplantation.