Applicability of laboratory deficit-based frailty index in predominantly older patients with end-stage renal disease under chronic dialysis: A pilot test of its correlation with survival and self-reported instruments

Frailty in Kidney Disease: A Comprehensive Review to Advance Its Clinical and Research Applications

Frailty is a multisystem syndrome of decreased physiologic reserve that has been shown to strongly and independently predict morbidity and mortality. Frailty is prevalent in patients living with kidney disease and occurs earlier in individuals with kidney disease as compared to the general population. In this comprehensive review, we examine clinical and research applications of frailty in kidney disease populations. Specifically, we clarify the definition of frailty and address common misconceptions, review the mechanisms and epidemiology of frailty in kidney disease, discuss challenges and limitations in frailty measurement, and provide updated evidence related to risk factors for frailty, its associated adverse outcomes, and interventions. We further add to the literature in this topic by highlighting the potential applications of frailty measurement in the care of patients with kidney disease and conclude with our recommendations for future research related to this important syndrome.

The association of a frailty index derived from laboratory tests and vital signs with clinical outcomes in critical care patients with septic shock: a retrospective study based on the MIMIC-IV database

PURPOSE

Frailty is a vulnerable state to stressors due to the loss of physiological reserve as a result of multisystem dysfunction. The physiological and laboratory-based frailty index (FI-Lab), depending on laboratory values and vital signs, is a powerful tool to capture frailty status. The aim of this study was to assess the relationship between FI-Lab and in-hospital mortality in patients with septic shock.

METHODS

Baseline data for patients with sepsis in the intensive care unit were retrieved from the Critical Care Medicine Database (MIMIC-IV, v2.2). The primary outcome was mortality during hospitalization. The propensity score matching (PSM) method was used to analyze the basic conditions during hospitalization between groups.The FI-Lab was analysed for its relationship with in-hospital mortality using logistic regression according to continuous and categorical variables, respectively, and described using the restricted cubic spline (RCS). Survival was compared between groups using Kaplan-Meier (KM) curves. Subgroup analyses were used to improve the stability of the results.

RESULTS

A total of 9219 patients were included. A cohort score of 1803 matched patients was generated after PSM. The analyses showed that non-surviving patients with septic shock in the ICU had a high FI-Lab index (P<0.001). FI-Lab, whether used as a continuous or categorical variable, increased with increasing FI-Lab and increased in-hospital mortality (P<0.001).Subgroup analyses showed similar results. RCS depicts this non-linear relationship. KM analysis shows the cumulative survival time during hospitalisation was significantly lower as FI-Lab increased (log-rank test, P<0.001).

CONCLUSION

Elevated FI-Lab is associated with increased in-hospital mortality in patients with septic shock.

Use of frailty assessment instruments in nephrology populations: a scoping review

BACKGROUND

Frailty is a clinical syndrome of accelerated aging associated with adverse outcomes. Frailty is prevalent among patients with chronic kidney disease but is infrequently assessed in clinical settings, due to lack of consensus regarding frailty definitions and diagnostic tools. This study aimed to review the practice of frailty assessment in nephrology populations and evaluate the context and timing of frailty assessment.

METHODS

The search included published reports of frailty assessment in patients with chronic kidney disease, undergoing dialysis or in receipt of a kidney transplant, published between January 2000 and November 2021. Medline, CINAHL, Embase, PsychINFO, PubMed and Cochrane Library databases were examined. A total of 164 articles were included for review.

RESULTS

We found that studies were most frequently set within developed nations. Overall, 161 studies were frailty assessments conducted as part of an observational study design, and 3 within an interventional study. Studies favoured assessment of participants with chronic kidney disease (CKD) and transplant candidates. A total of 40 different frailty metrics were used. The most frequently utilised tool was the Fried frailty phenotype. Frailty prevalence varied across populations and research settings from 2.8% among participants with CKD to 82% among patients undergoing haemodialysis. Studies of frailty in conservatively managed populations were infrequent (N = 4). We verified that frailty predicts higher rates of adverse patient outcomes. There is sufficient literature to justify future meta-analyses.

CONCLUSIONS

There is increasing recognition of frailty in nephrology populations and the value of assessment in informing prognostication and decision-making during transitions in care. The Fried frailty phenotype is the most frequently utilised assessment, reflecting the feasibility of incorporating objective measures of frailty and vulnerability into nephrology clinical assessment. Further research examining frailty in low and middle income countries as well as first nations people is required. Future work should focus on interventional strategies exploring frailty rehabilitation.

Development, validation and performance of laboratory frailty indices: A scoping review

INTRODUCTION

Frailty is a syndrome characterised by decline in functional ability and increasing vulnerability to disease and associated with adverse outcomes. Several established methods exist for assessing frailty. This scoping review aims to characterise the development and validation of frailty indices based on laboratory test results (FI-Lab) and to assess their utility.

METHODS

Studies were included in the review if they included data concerning the development and/or testing an FI-Lab using the deficit accumulation method. Studies were identified using PubMed/MEDLINE, Embase (Elsevier), OpenGrey and Google Scholar from 2010 to 2021. Two reviewers independently screened all abstracts, and those that met the inclusion criteria were reviewed in detail. Data extracted included details about the study characteristics, number, type and coding of laboratory variables included, validation, and outcomes. A narrative synthesis of the available evidence was adopted.

RESULTS

The search yielded 915 articles, of which 29 studies were included. In general, 89% of studies were conducted after 2016 and 51% in a hospital-based setting. The number of variables included in FI-Labs ranged from 13 to 77, and 51% included some non-laboratory variables in their indices, with pulse and blood pressure being the most frequent. The validity of FI-Lab was demonstrated through change with age, correlation with established frailty indices and association with adverse health outcomes. The most frequent outcome studied was mortality (79% of the studies), with FI-Lab associated with increased mortality in all but one. Other outcomes studied included self-reported health, institutionalisation, and activities of daily living. The effect of combining the FI-Lab with a non-laboratory-based FI was assessed in 7 studies with a marginal increase in predictive ability.

CONCLUSION

Frailty indices constructed based on the assessment of laboratory variables, appear to be a valid measure of frailty and robust to the choice of variables included.

The frailty index based on laboratory test data as a tool to investigate the impact of frailty on health outcomes: a systematic review and meta-analysis

The frailty index (FI) quantifies frailty as deficit accumulation. It has been adapted to employ laboratory test data (FI-Lab). Our objective was to systematically review and meta-analyse the FI-Lab's ability to predict mortality. Secondary objectives were to review the FI-Lab's association with adverse health outcomes and whether FI-Lab scores differed between the sexes. A systematic literature search was carried out using six online databases to identify studies that measured the FI-Lab in humans. Hazard ratios (HRs) were combined in a meta-analysis to create a pooled risk estimate for mortality. Of the 1,201 papers identified, spanning January 2010 until 11 July 2022, 38 were included. FI-Lab scores per 0.01 unit increase predicted mortality overall (HR = 1.04; 95% confidence interval (CI) = 1.03-1.05) and for studies with a mean age of 81+ years (HR = 1.04; 95% CI = 1.03-1.05). The quality of evidence for these meta-analyses are moderate and high, respectively. Further, higher FI-Lab scores were associated with more frequent adverse health outcomes. Sex differences in FI-Lab scores varied, with no consistent indication of a sex effect. The FI-Lab is associated with mortality and with a variety of adverse health outcomes. No consistent sex differences in FI-Lab scores were observed, with several studies in disagreement. Notably, these conclusions were most relevant to older (65+ years old) individuals; further evidence in younger people is needed in both clinical and population representative studies.

Development of an Administrative Data-Based Frailty Index for Older Adults Receiving Dialysis

Background

Frailty is present in ≥50% of older adults receiving dialysis. Our objective was to a develop an administrative data–based frailty index and assess the frailty index’s predictive validity for mortality and future hospitalizations.

Methods

We used United States Renal Data System data to establish two cohorts of adults aged ≥65 years, initiating dialysis in 2013 and in 2017. Using the 2013 cohort (development dataset), we applied the deficit accumulation index approach to develop a frailty index. Adjusting for age and sex, we assessed the extent to which the frailty index predicts the hazard of time until death and time until first hospitalization over 12 months. We assessed the Harrell’s C-statistic of the frailty index, a comorbidity index, and jointly. The 2017 cohort was used as a validation dataset.

Results

Using the 2013 cohort (n=20,974), we identified 53 deficits for the frailty index across seven domains: disabilities, diseases, equipment, procedures, signs, tests, and unclassified. Among those with ≥1 deficit, the mean (SD) frailty index was 0.30 (0.13), range 0.02–0.72. Over 12 months, 18% (n=3842) died, and 55% (n=11,493) experienced a hospitalization. Adjusted hazard ratios for each 0.1-point increase in frailty index in models of time to death and time to first hospitalization were 1.41 (95% confidence interval, 1.37 to 1.44) and 1.33 (95% confidence interval, 1.31 to 1.35), respectively. For mortality, C-statistics for frailty index, comorbidity index, and both indices were 0.65, 0.65, and 0.66, respectively. For hospitalization, C-statistics for frailty index, comorbidity index, and both indices were 0.61, 0.60, and 0.61, respectively. Data from the 2017 cohort were similar.

Conclusions

We developed a novel frailty index for older adults receiving dialysis. Further studies are needed to improve on this frailty index and validate its use for clinical and research applications.

The association of a frailty index from laboratory tests and vital signs with clinical outcomes in hospitalized older adults

BACKGROUND

Frailty, a state of vulnerability to stressors resulting from loss of physiological reserve due to multisystemic dysfunction, is common among hospitalized older adults. Hospital clinicians need objective and practical instruments that identify older adults with frailty. The FI-LAB is based on laboratory values and vital signs and may capture biological changes of frailty that predispose hospitalized older adults to complications. The study's aim was to assess the association of the FI-LAB versus VA-FI with hospital and post-hospital clinical outcomes in older adults.

METHODS

Retrospective cohort study was conducted on Veterans aged ≥60 admitted to a VA hospital. We identified acute hospitalizations January 2011-December-2014 with 1-year follow-up. A 31-item FI-LAB was created from blood laboratory tests and vital signs collected within the first 48 h of admission and scores were categorized as low (<0.25), moderate (0.25-0.40), and high (>0.40). For each FI-LAB group, we obtained odds ratio (OR) and confidence intervals (CI) for hospital and post-hospital outcomes using multivariate binomial logistic regression. Additionally, we calculated hazard ratios (HR) and CI for all-cause in-hospital mortality comparing the high and moderate FI-LAB group with the low group.

RESULTS

Patients were 1407 Veterans, mean age 72.7 (SD = 9.0), 67.8% Caucasian, 96.1% males, 47.0% (n = 661), 41.0% (n = 577), and 12.0% (n = 169) were in the low, moderate, and high FI-LAB groups, respectively. Moderate and high scores were associated with prolonged LOS, OR:1.62 (95% CI:1.29-2.03); and 3.36 (95% CI:2.27-4.99), ICU admission, OR:1.40 (95% CI:1.03-1.90); and OR:2.00 (95% CI:1.33-3.02), nursing home placement OR:2.36 (95% CI:1.26-4.44); and 5.99 (95% CI:2.83-12.70), 30-day readmissions OR:1.74 (95% CI:1.20-2.52); and 2.20 (95% CI:1.30-3.74), 30-day mortality OR: 2.51 (95% CI:1.01-6.23); and 8.97 (95% CI:3.42-23.53), 6-month mortality OR:3.00 (95% CI:1.90-4.74); and 6.16 (95% CI:3.55-10.71), and 1-year mortality OR: 2.66 (95% CI:1.87-3.79); and 4.76 (95% CI:3.00-7.54) respectively. The high FI-LAB group showed higher risk of in-hospital mortality, HR:18.17 (95% CI:4.01-80.52) with an area-under-the-curve of 0.843 (95% CI:0.75-0.93).

CONCLUSIONS

High and moderate FI-LAB scores were associated with worse in-hospital and post-hospital outcomes. The FI-LAB may identify hospitalized older patients with frailty at higher risk and assist clinicians in implementing strategies to improve outcomes.

Uremic Toxins and Frailty in Patients with Chronic Kidney Disease: A Molecular Insight

The accumulation of uremic toxins (UTs) is a prototypical manifestation of uremic milieu that follows renal function decline (chronic kidney disease, CKD). Frailty as a potential outcome-relevant indicator is also prevalent in CKD. The intertwined relationship between uremic toxins, including small/large solutes (phosphate, asymmetric dimethylarginine) and protein-bound ones like indoxyl sulfate (IS) and p-cresyl sulfate (pCS), and frailty pathogenesis has been documented recently. Uremic toxins were shown in vitro and in vivo to induce noxious effects on many organ systems and likely influenced frailty development through their effects on multiple preceding events and companions of frailty, such as sarcopenia/muscle wasting, cognitive impairment/cognitive frailty, osteoporosis/osteodystrophy, vascular calcification, and cardiopulmonary deconditioning. These organ-specific effects may be mediated through different molecular mechanisms or signal pathways such as peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α), mitogen-activated protein kinase (MAPK) signaling, aryl hydrocarbon receptor (AhR)/nuclear factor-κB (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), Runt-related transcription factor 2 (RUNX2), bone morphogenic protein 2 (BMP2), osterix, Notch signaling, autophagy effectors, microRNAs, and reactive oxygen species induction. Anecdotal clinical studies also suggest that frailty may further accelerate renal function decline, thereby augmenting the accumulation of UTs in affected individuals. Judging from these threads of evidence, management strategies aiming for uremic toxin reduction may be a promising approach for frailty amelioration in patients with CKD. Uremic toxin lowering strategies may bear the potential of improving patients’ outcomes and restoring their quality of life, through frailty attenuation. Pathogenic molecule-targeted therapeutics potentially disconnect the association between uremic toxins and frailty, additionally serving as an outcome-modifying approach in the future.

Vascular Calcification as an Underrecognized Risk Factor for Frailty in 1783 Community-Dwelling Elderly Individuals

Background

Vascular calcification (VC) is associated with high morbidity and mortality among older adults, a population that exhibits a higher tendency for developing frailty at the same time. Whether VC serves as a risk factor for the development of frailty in this population remains unclear.

Methods and Results

We analyzed a prospectively assembled cohort of community‐dwelling older adults between 2014 and 2017 (n=1783). Frailty and prefrailty were determined on the basis of the Study of Osteoporotic Fractures criteria, and VC was measured using semiquantitative aortic arch calcification (AAC) and abdominal aortic calcification scoring. We conducted multiple logistic regression with prefrailty or frailty as the dependent variable, incorporating sociodemographic profiles, comorbidities, medications, laboratory data, AAC status/severity, and other geriatric phenotypes. Among all participants, 327 (18.3%) exhibited either prefrailty (15.3%) or frailty (3.1%), and 648 (36.3%) exhibited AAC. After adjusting for multiple confounders, we found that AAC incidence was associated with a substantially higher probability of prefrailty or frailty (odds ratio [OR], 11.9; 95% CI, 7.9–15.4), with a dose‐responsive relationship (OR for older adults with AAC categories 1, 2, and 3 was 9.3, 13.6, and 52.5, respectively). Similar association was observed for older adults with abdominal aortic calcification (OR, 5.0; 95% CI, 1.3–19.5), and might be replicable in another cohort of patients with end‐stage renal disease.

Conclusions

Severity of VC exhibited a linear positive relationship with frailty in older adults. Our findings suggest that a prompt diagnosis and potential management of VC may assist in risk mitigation for patients with frailty.

Elevated Red Cell Distribution Width Is Independently Associated With a Higher Frailty Risk Among 2,932 Community-Dwelling Older Adults

Background: Older adults are at an increased risk of frailty, but laboratory surrogates for identifying frailty in this population remain controversial and clinicians frequently encounter difficulty during frailty screening. We examined whether having a high red cell distribution width (RDW) was associated with an increased probability of frailty in older adults.

Methods: We prospectively included community-dwelling older adults between 2013 and 2016 from a single institute, with their clinical features/laboratory parameters documented. We used the Study of Osteoporotic Fractures index (malnutrition, poor physical performance, and fatigue) to delineate frailty, and harnessed multiple logistic regression to investigate whether having a high RDW (≥ 15.7%) was associated with an increased risk of having frailty among these participants.

Results: A total of 2,932 older adults (mean 73.5 ± 6.7 years; 44.6% male) were included, among whom 113 (3.9%) and 76 (2.6%) had a high RDW and presented frailty, respectively. Older adults with a high RDW were more likely to be frail (p = 0.002) and had more positive SOF items than those with normal RDW levels (p = 0.013). Those with a high RDW exhibited a significantly higher risk of having frailty (odds ratio [OR] 2.689, 95% confidence interval [CI] 1.184–6.109) compared to those without. Sensitivity analyses using RDW as a continuous variable similarly showed that RDW levels were positively associated with frailty risk (OR 1.223 per 1% RDW higher).

Conclusions: In older adults, higher RDW can be regarded as a frailty indicator, and the readiness in RDW assessment supports its screening utility.

Gustatory Dysfunction Is Closely Associated With Frailty in Patients With Chronic Kidney Disease

OBJECTIVE

Gustatory function is frequently impaired in patients with chronic kidney disease (CKD), and the associated taste dysfunction contributes to compromised nutrition. Whether gustatory dysfunction is an underappreciated risk factor for frailty in patients with CKD remains unclear. The objective of this work was to examine the role of gustatory dysfunction as a risk factor for frailty in patients with CKD.

METHODS

We prospectively enrolled patients with stage 3 or higher CKD from a single institute, with their gustatory function assessed using both objective (taste strip method) and subjective approaches, and frailty identified using the Edmonton frail scale, FRAIL scale, and Study of Osteoporotic Fracture (SOF) scale. Multiple regression analyses were performed to investigate whether results from gustatory function tests independently correlated with frailty.

RESULTS

Among the enrolled patients with CKD, 14 (17.9%) were found to be frail. We discovered that higher taste strip scores, or better taste function, were significantly associated with a lower frail probability (odds ratio [OR] 0.74 per score, 95% confidence interval [CI] 0.57-0.97), independent of clinical features, while better subjective taste function (OR 0.84 per score, 95% CI 0.74-0.96) and better oral cavity intactness (OR, 0.94; 95% CI, 0.9-0.98) were similarly associated with a lower frail probability among patients with CKD.

CONCLUSION

Gustatory dysfunction may be an important risk factor for frailty in patients with CKD. It is tempting to presume that interventions aiming to ameliorate such deficits may bear the potential of reducing frailty severity in this population with a high frailty burden.