Development and Validation of an Abridged Physical Frailty Phenotype for Clinical Use: A Cohort Study Among Kidney Transplant Candidates.

BACKGROUND: Frailty is associated with poor outcomes in surgical patients including kidney transplant (KT) recipients. Transplant centers that measure frailty have better pre- and postoperative outcomes. However, clinical utility of existing tools is low due to time constraints. To address this major barrier to implementation in the preoperative evaluation of patients, we developed an abridged frailty phenotype. METHODS: The abridged frailty phenotype was developed by simplifying the 5 physical frailty phenotype (PFP) components in a two-center prospective cohort of 3 220 KT candidates and tested for efficiency (time to completion) in 20 candidates evaluation (January 2009 to March 2020). We examined area under curve (AUC) and Cohen's kappa agreement to compare the abridged assessment with the PFP. We compared waitlist mortality risk (competing risks models) by frailty using the PFP and abridged assessment, respectively. Model discrimination was assessed using Harrell's C-statistic. RESULTS: Of 3 220 candidates, the PFP and abridged assessment identified 23.8% and 27.4% candidates as frail, respectively. The abridged frailty phenotype had substantial agreement (kappa = 0.69, 95% CI: 0.66-0.71) and excellent discrimination (AUC = 0.861). Among 20 patients at evaluation, abridged assessment took 5-7 minutes to complete. The PFP 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 (p = .51). CONCLUSIONS: The abridged assessment is an efficient and valid way to identify frailty. It predicts waitlist mortality without sacrificing discrimination. Surgical departments should consider utilizing the abridged assessment to evaluate frailty in patients when time is limited.

Association of Postoperative Delirium With Incident Dementia and Graft Outcomes Among Kidney Transplant Recipients.

BACKGROUND: Kidney transplant (KT) recipients have numerous risk factors for delirium, including those shared with the general surgical population (eg, age and major surgery) and transplant-specific factors (eg, neurotoxic immunosuppression medications). Evidence has linked delirium to long-term dementia risk in older adults undergoing major surgery. We sought to characterize dementia risk associated with post-KT delirium. METHODS: Using the United States Renal Data System datasets, we identified 35 800 adult first-time KT recipients ≥55 y. We evaluated risk factors for delirium using logistic regression. We evaluated the association between delirium and incident dementia (overall and by subtype: Alzheimer's, vascular, and other/mixed-type), graft loss, and death using Fine and Gray's subhazards models and Cox regression. RESULTS: During the KT hospitalization, 0.9% of recipients were diagnosed with delirium. Delirium risk factors included age (OR = 1.40, 95% CI, 1.28-1.52) and diabetes (OR = 1.38, 95% CI, 1.10-1.73). Delirium was associated with higher risk of death-censored graft loss (aHR = 1.52, 95% CI, 1.12-2.05) and all-cause mortality (aHR = 1.53, 95% CI, 1.25-1.89) at 5 y post-KT. Delirium was also associated with higher risk of dementia (adjusted subhazard ratio [aSHR] = 4.59, 95% CI, 3.48-6.06), particularly vascular dementia (aSHR = 2.51, 95% CI, 1.01-6.25) and other/mixed-type dementia (aSHR = 5.58, 95% CI, 4.24-7.62) subtypes. The risk of all-type dementia associated with delirium was higher for younger recipients aged between 55 and 64 y ( Pinteraction = 0.01). CONCLUSIONS: Delirium is a strong risk factor for subsequent diagnosis of dementia among KT recipients, particularly those aged between 55 and 64 y at the time of transplant. Patients experiencing posttransplant delirium might benefit from early interventions to enhance cognitive health and surveillance for cognitive impairment to enable early referral for dementia care.

Order of Onset of Physical Frailty and Cognitive Impairment and Risk of Repeated Falls in Community-Dwelling Older Adults.

OBJECTIVES: To examine whether physical frailty onset before, after, or in concert with cognitive impairment is differentially associated with fall incidence in community-dwelling older adults. DESIGN: A longitudinal observational study. SETTING AND PARTICIPANTS: Data from 1337 older adults age ≥65 years and free of physical frailty or cognitive impairment at baseline were obtained from the National Health Aging Trends Study (2011‒2017), a nationally representative cohort study of US older adult Medicare beneficiaries. METHODS: Participants were assessed annually for frailty (physical frailty phenotype) and cognitive impairment (bottom quintile of clock drawing test or immediate and delayed recall; or proxy-report of diagnosis of dementia or AD8 score of ≥2). Incident falls were ascertained annually via self-report. Multinomial logistic regression was performed to estimate the association between order of first onset of cognitive impairment and/or frailty and incident single or repeated falls in the 1-year interval following their first onset. RESULTS: Of the 1,337, 832 developed cognitive impairment first (termed "CI first"), 286 developed frailty first (termed "frailty first") and 219 had co-occurrence of cognitive impairment and frailty within one year (termed "CI-frailty co-occurrence") over 5 years. Overall, 491 (34.5%) had at least 1 fall during the 1-year interval following the onset of physical frailty and/or cognitive impairment. After adjustment, "CI-frailty co-occurrence" was associated with a more than 2-fold increased risk of repeated falls than "CI first" (odds ratio 2.35, 95% confidence interval 1.51‒3.67; P < .001). No significant difference was found between participants with "frailty first" and "CI first" (P = .07). In addition, the order of onset was not associated with risk of a single fall. CONCLUSIONS AND IMPLICATIONS: Older adults experiencing "CI-frailty co-occurrence" had the greatest risk of repeated falls compared with those with "CI first" and "frailty first". Fall risk screening should consider the order and timing of onset of physical frailty and cognitive impairment.

Sleep duration and cognitive function among older adults with chronic kidney disease: results from the National Health and Nutrition Examination Survey (2011-2014).

BACKGROUND: Short and long sleep durations are associated with cognitive dysfunction. Given the increased prevalence of sleep abnormalities in the chronic kidney disease (CKD) population, we tested whether the association between sleep duration and cognitive function differed between older adults with and without CKD. METHODS: This was a study of 3215 older adults (age ≥60 years) enrolled in the National Health and Nutrition Examination Survey (2011-14) evaluating sleep duration, cognitive function (immediate recall, delayed recall, verbal fluency, executive function and processing speed and global cognition) and kidney function. We quantified the association between sleep duration and cognitive function using linear regression and tested whether the associations differed among those with CKD and without using a Wald test for interaction. RESULTS: Among 3215 participants, 13.3% reported 2-5 hours of sleep/day, 75.2% reported 6-8 hours, and 11.5% reported ≥9 hours. Persons with CKD were more likely to sleep ≥9 hours [odds ratio 1.73 (95% confidence interval 1.22-2.46)]. Among participants with CKD, those with a sleep duration ≥9 hours demonstrated worse global cognitive function (P for interaction = .01), immediate recall (P for interaction = .01) and verbal fluency (P for interaction = .004) than those with a sleep duration of 6-8 h; no differences were observed for participants with CKD who slept 2-5 hours. Among participants without CKD, sleep was not associated with any measures of cognitive function. CONCLUSIONS: Longer sleep duration is associated with worse cognitive function only among persons with CKD, and global cognition, delayed recall and verbal fluency are particularly affected. Studies should identify interventions to improve sleep patterns and quality in this population.

Domains for a Comprehensive Geriatric Assessment of Older Adults with Chronic Kidney Disease: Results from the CRIC Study.

INTRODUCTION: A comprehensive geriatric assessment (CGA) tailored to the chronic kidney disease (CKD) population would yield a more targeted approach to assessment and care. We aimed to identify domains of a CKD-specific CGA (CKD-CGA), characterize patterns of these domains, and evaluate their predictive utility on adverse health outcomes. METHODS: We used data from 864 participants in the Chronic Renal Insufficiency Cohort aged ≥55 years and not on dialysis. Constituents of the CKD-CGA were selected a priori. Latent class analysis informed the selection of domains and identified classes of participants based on their domain patterns. The predictive utility of class membership on mortality, dialysis initiation, and hospitalization was examined. Model discrimination was assessed with C-statistics. RESULTS: The CKD-CGA included 16 domains: cardiovascular disease, diabetes, five frailty phenotype components, depressive symptoms, cognition, five kidney disease quality-of-life components, health literacy, and medication use. A two-class latent class model fit the data best, with 34.7% and 65.3% in the high- and low-burden of geriatric conditions classes, respectively. Relative to the low-burden class, participants in the high-burden class were at increased risk of mortality (aHR = 2.09; 95% CI: 1.56, 2.78), dialysis initiation (aHR = 1.63; 95% CI: 1.06, 2.52), and hospitalization (aOR = 2.00; 95% CI: 1.38, 2.88). Model discrimination was the strongest for dialysis initiation (C-statistics = 0.86) and moderate for mortality and hospitalization (C-statistics = 0.70 and 0.66, respectively). CONCLUSION: With further validation in an external cohort, the CKD-CGA has the potential to be used in nephrology practices for assessing and managing geriatric conditions in older adults with CKD.

Delirium, changes in cognitive function, and risk of diagnosed dementia after kidney transplantation.

Kidney transplant (KT) recipients with delirium, a preventable surgical complication, are likely to reap cognitive benefits from restored kidney function, but may be more vulnerable to longer-term neurotoxic stressors post-KT (i.e., aging, immunosuppression). In this prospective cohort study, we measured delirium (chart-based), global cognitive function (3MS), and executive function (Trail Making Test Part B minus Part A) in 894 recipients (2009-2021) at KT, 1/3/6-months, 1-year, and annually post-KT. Dementia was ascertained using linked Medicare claims. We described repeated measures of cognitive performance (mixed effects model) and quantified dementia risk (Fine & Gray competing risk) by post-KT delirium. Of 894 recipients, 43(4.8%) had post-KT delirium. Delirium was not associated with global cognitive function at KT (difference = -3.2 points, 95%CI: -6.7, 0.4) or trajectories post-KT (0.03 points/month, 95%CI: -0.27, 0.33). Delirium was associated with worse executive function at KT (55.1 s, 95%CI: 25.6, 84.5), greater improvements in executive function <2 years post-KT (-2.73 s/month, 95%CI: -4.46,-0.99), and greater decline in executive function >2 years post-KT (1.72 s/month, 95%CI: 0.22, 3.21). Post-KT delirium was associated with over 7-fold greater risk of dementia post-KT (adjusted subdistribution hazard ratio = 7.84, 95%CI: 1.22, 50.40). Transplant centers should be aware of cognitive risks associated with post-KT delirium and implement available preventative interventions to reduce delirium risk.

Patient Perspectives on the Use of Frailty, Cognitive Function, and Age in Kidney Transplant Evaluation.

BACKGROUND: The allocation of scarce deceased donor kidneys is a complex process. Transplant providers are increasingly relying on constructs such as frailty and cognitive function to guide kidney transplant (KT) candidate selection. Patient views of the ethical issues surrounding the use of such constructs are unclear. We sought to assess KT candidates' attitudes and beliefs about the use of frailty and cognitive function to guide waitlist selection. METHODS: KT candidates were randomly recruited from an ongoing single-center cohort study of frailty and cognitive function. Semi-structured interviews were conducted, and thematic analysis was performed. Inductively derived themes were mapped onto bioethics principles. RESULTS: Twenty interviews were conducted (65% contact rate, 100% participation rate) (60% male; 70% White). With respect to the use of frailty and cognitive function in waitlisting decisions, four themes emerged in which participants: (1) valued maximizing a scarce resource (utility); (2) prioritized equal access to all patients (equity); (3) appreciated a proportional approach to the use of equity and utility (precautionary utility); and (4) sought to weigh utility- and equity-based concerns regarding social support. While some participants believed frailty and cognitive function were useful constructs to maximize utility, others believed their use would jeopardize equity. Patients were uncomfortable with using single factors such as frailty or cognitive impairment to deny someone access to transplantation; participants instead encouraged using the constructs to identify opportunities for intervention to improve frailty and cognitive function prior to KT. CONCLUSIONS: KT candidates' values mirrored the current allocation strategy, seeking to balance equity and utility in a just manner, albeit with conflicting viewpoints on the appropriate use of frailty and cognitive impairment in waitlisting decisions.

Depressive Symptoms at Kidney Transplant Evaluation and Access to the Kidney Transplant Waitlist.

Introduction: Depressive symptoms, even without a clinical diagnosis of depression, are common in kidney failure patients and may be a barrier to completing the complex process of kidney transplant (KT) evaluation. We assessed depressive symptom burden and association between depressive symptoms and access to KT waitlist by age. Methods: In a prospective cohort of 3728 KT patients (aged 18-88 years), the Center for Epidemiologic Studies-Depression (CES-D) scale was used to measure depressive symptoms at evaluation. Depressive symptom severity was defined as follows: none: 0; minimal: 1 to 15; mild: 16 to 20; moderate: 21 to 25; severe: 26 to 60. Hazard ratios (HRs) of active listing within 1 year after evaluation were estimated using Cox proportional hazards models, adjusted for clinical and social factors. Results: At evaluation, 85.8% of the patients reported at least minimal depressive symptoms; the proportion was lower among older patients: 18 to 29 years = 92.0%; 30 to 39 years = 88.3%; 40 to 49 years = 87.2%; 50 to 59 years = 87.0%; 60 to 69 years = 83.4%; and ≥70 years = 82.0%. Chance of active listing decreased with more severe depressive symptoms (log-rank, P < 0.001). After adjustment, every 5-point higher CES-D score (more depressive symptoms) was associated with a 13% lower chance of listing (HR = 0.87, 95% CI: 0.85-0.90); the strongest association was found among patients aged ≥70 years (adjusted HR [aHR] = 0.73, 95% CI: 0.62-0.86). Furthermore, minimal (HR = 0.69, 95% CI: 0.60-0.79), mild (HR = 0.57, 95% CI: 0.44-0.72), moderate (HR = 0.53, 95% CI: 0.39-0.71), and severe (HR = 0.44, 95% CI: 0.34-0.57) depressive symptoms were all associated with a lower chance of listing. Conclusion: Older candidates were less likely to report depressive symptoms at KT evaluation. Regardless of age, candidates who did report depressive symptoms, and even minimal symptoms, had a lower chance of listing. Transplant centers should routinely screen patients for depressive symptoms and refer the affected patients to mental health services to improve access to KT.

Secondary hyperparathyroidism (CKD-MBD) treatment and the risk of dementia.

BACKGROUND: Elevated parathyroid hormone (PTH) levels have been reported as a potential risk factor for cognitive impairment. Compared with the general population, older adults with end-stage renal disease (ESRD) who are frequently affected by secondary hyperparathyroidism (SHPT) are at increased risk of developing dementia. The main objective of our study was to evaluate if the risk of dementia in older (age ≥66 years) ESRD patients differed if they were treated for SHPT. METHODS: Using the United States Renal Data System and Medicare claims, we identified 189 433 older adults without a diagnosis of dementia, who initiated dialysis between 2006 and 2016. SHPT treatment was defined as the use of vitamin D analogs, phosphate binders, calcimimetics or parathyroidectomy. We quantified the association between treated SHPT and incident dementia during dialysis using a multivariable Cox proportional hazards model with inverse probability weighting, considering SHPT treatment as a time-varying exposure. RESULTS: Of 189 433 older ESRD adults, 92% had a claims diagnosis code of SHPT and 123 388 (65%) were treated for SHPT. The rate of incident dementia was 6 cases per 100 person-years among SHPT treated patients compared with 11 cases per 100 person-years among untreated patients. Compared with untreated SHPT patients, the risk of dementia was 42% lower [adjusted hazard ratio (aHR) = 0.58, 95% confidence interval (CI): 0.56-0.59] among SHPT treated patients. The magnitude of the beneficial effect of SHPT treatment differed by sex (Pinteraction = .02) and race (Pinteraction ≤ .01), with females (aHR = 0.56, 95% CI: 0.54-0.58) and those of Asian (aHR = 0.51, 95% CI: 0.46-0.57) or Black race (aHR = 0.51, 95% CI: 0.48-0.53) having a greatest reduction in dementia risk. CONCLUSION: Receiving treatment for SHPT was associated with a lower risk of incident dementia among older patients with ESRD. This work provides additional support for the treatment of SHPT in older ESRD patients.

Long-Term Trajectories of Frailty and Its Components After Kidney Transplantation.

BACKGROUND: Frailty is common and associated with poor outcomes among kidney transplant (KT) recipients. While frailty improves in the first 3 months post-KT with restored kidney function, longer-term trajectories are likely to plateau/decline due to aging and other stressors (eg, immunosuppression). We evaluated longer-term post-KT trajectories of the physical frailty phenotype (PFP) and its components in adult patients at 2 centers. METHODS: PFP components were measured at admission, 1, 3, 6 months, 1 year, and annually thereafter post-KT. We used adjusted mixed-effects models to describe repeated measures of continuous components (weight, gait speed, grip strength, activity) and generalized estimating equations to quantify longitudinal, binomial response patterns (PFP; exhaustion). RESULTS: Among 1 336 recipients (mean age = 53) followed for a median of 1.9 years (interquartile range [IQR] = 0.1-3.2), likelihood of frailty declined in the first 2.5 years post-KT (adjusted odds ratio [aOR] = 0.96, 95% confidence interval [CI]: 0.95, 0.98), but increased after 2.5 years post-KT (aOR = 1.03, 95% CI: 1.00, 1.05). In the first 2.5 years post-KT, recipients demonstrated increases in weight (0.4 lbs/month, 95% CI: 0.3, 0.5), grip strength (0.2 kg/month, 95% CI: 0.1, 0.2), and activity (23.9 kcal/month, 95% CI: 17.5, 30.2); gait speed remained stable (-0.01 s/month, 95% CI: 0.01, 0.003). Additionally, likelihood of becoming exhausted declined post-KT (OR = 0.99, 95% CI: 0.98, 1.00). After 2.5 years post-KT, recipients demonstrated decreased grip strength (-0.07 kg/month, 95% CI: -0.12, -0.01) and activity (-20 kcal/month, 95% CI: -32.3, -8.2); they had stable weight (-0.003 lbs/month, 95% CI: -0.17, 0.16), gait speed (-0.003 s/month, 95% CI: -0.02, 0.01), and likelihood of becoming exhausted (OR = 1.01, 95% CI: 0.99, 1.02). CONCLUSION: Despite frailty improvements in the first 2.5 years, recipients' frailty worsened after 2.5 years post-KT. Specifically, they experienced gains in strength, activity, and exhaustion in the first 2.5 years post-KT, but declined in strength and activity after 2.5 years post-KT while experiencing persistent slowness. Clinicians should consider monitoring recipients for worsening frailty after 2.5 years despite shorter-term improvements.

Transplant centers that assess frailty as part of clinical practice have better outcomes.

BACKGROUND: Frailty predicts adverse post-kidney transplant (KT) outcomes, yet the impact of frailty assessment on center-level outcomes remains unclear. We sought to test whether transplant centers assessing frailty as part of clinical practice have better pre- and post-KT outcomes in all adult patients (≥18 years) and older patients (≥65 years). METHODS: In a survey of US transplant centers (11/2017-4/2018), 132 (response rate = 65.3%) centers reported their frailty assessment practices (frequency and specific tool) at KT evaluation and admission. Assessment frequency was categorized as never, sometime, and always; type of assessment tool was categorized as none, validated (for post-KT risk prediction), and any other tool. Center characteristics and clinical outcomes for adult patients during 2017-2019 were gleaned from the transplant national registry (Scientific Registry of Transplant Recipients). Poisson regression was used to estimate incidence rate ratios (IRRs) of waitlist outcomes (waitlist mortality, transplantation) in candidates and IRRs of post-KT outcomes (all-cause mortality, death-censored graft loss) in recipients by frailty assessment frequency. We also estimated IRRs of waitlist outcomes by type of assessment tool at evaluation. All models were adjusted for case mix and center characteristics. RESULTS: Assessing frailty at evaluation was associated with lower waitlist mortality rate (always IRR = 0.91,95%CI:0.84-0.99; sometimes = 0.89,95%CI:0.83-0.96) and KT rate (always = 0.94,95%CI:0.91-0.97; sometimes = 0.88,95%CI:0.85-0.90); the associations with waitlist mortality rate (always = 0.86,95%CI:0.74-0.99; sometimes = 0.83,95%CI:0.73-0.94) and KT rate (always = 0.82,95%CI:0.77-0.88; sometimes = 0.92,95%CI:0.87-0.98) were stronger in older patients. Furthermore, using validated (IRR = 0.90,95%CI:0.88-0.92) or any other tool (IRR = 0.90,95%CI:0.87-0.93) at evaluation was associated lower KT rate, while only using a validated tool was associated with lower waitlist mortality rate (IRR = 0.89,95%CI:0.83-0.96), especially in older patients (IRR = 0.82,95%CI:0.72-0.93). At admission for KT, always assessing frailty was associated with a lower graft loss rate (IRR = 0.71,95%CI:0.54-0.92) but not with mortality (IRR = 0.93,95%CI:0.76-1.13). CONCLUSIONS: Assessing frailty at evaluation is associated with lower KT rate, while only using a validated frailty assessment tool is associated with better survival, particularly in older candidates. Centers always assessing frailty at admission are likely to have better graft survival rates. Transplant centers may utilize validated frailty assessment tools to secure KT access for appropriate candidates and to better allocate health care resources for patients identified as frail, particularly for older patients.

Evolving Trends in Risk Profiles and Outcomes in Older Adults Undergoing Kidney Retransplantation.

BACKGROUND: In older adults (≥65), access to and outcomes following kidney transplantation (KT) have improved over the past 3 decades. It is unknown if there were parallel trends in re-KT. We characterized the trends, changing landscape, and outcomes of re-KT in older adults. METHODS: Among the 44,149 older kidney-only recipients (1995-2016) in the Scientific Registry of Transplant Recipients, we identified 1743 who underwent re-KT. We analyzed trends and outcomes (mortality, death-censored graft failure [DCGF]) by eras (1995-2002, 2003-2014, and 2015-2016) that were defined by changes to the expanded criteria donors and Kidney Donor Profile Index policies. RESULTS: Among all older kidney-only recipients during 1995-2002, 2003-2014, 2015-2016 the proportion that were re-KTs increased from 2.7% to 4.2% to 5.7%, P < 0.001, respectively. Median age at re-KT (67-68-68, P = 0.04), years on dialysis after graft failure (1.4-1.5-2.2, P = 0.003), donor age (40.0-43.0-43.5, P = 0.04), proportion with panel reactive antibody 80-100 (22.0%-32.7%-48.7%, P < 0.001), and donation after circulatory death (1.1%-13.4%-19.5%, P < 0.001) have increased. Despite this, the 3-y cumulative incidence for mortality (22.3%-19.1%-11.5%, P = 0.002) and DCGF (13.3%-10.0%-5.1%, P = 0.01) decreased over time. Compared with deceased donor retransplant recipients during 1995-2002, those during 2003-2014 and 2015-2016 had lower mortality hazard (aHR = 0.78, 95% confidence interval, 0.63-0.86 and aHR = 0.55, 95% confidence interval, 0.35-0.86, respectively). These declines were noted but not significant for DCGF and in living donor re-KTs. CONCLUSIONS: In older retransplant recipients, outcomes have improved significantly over time despite higher risk profiles; yet they represent a fraction of the KTs performed. Our results support increasing access to re-KT in older adults; however, approaches to guide the selection and management in those with graft failure need to be explored.

Chronic kidney disease, physical activity and cognitive function in older adults-results from the National Health and Nutrition Examination Survey (2011-2014).

BACKGROUND: Cognitive impairment is common among persons with chronic kidney disease (CKD), due in part to reduced kidney function. Given that physical activity (PA) is known to mitigate cognitive decline, we examined whether associations between CKD stage and global/domain-specific cognitive function differ by PA. METHODS: We leveraged 3223 participants (≥60 years of age) enrolled in National Health and Nutrition Examination Survey (NHANES, 2011-2014), with at least one measure of objective cognitive function [immediate recall (CERAD-WL), delayed recall (CERAD-DR), verbal fluency (AF), executive function/processing speed (DSST), global (average of four tests) or self-perceived memory decline (SCD)]. We quantified the association between CKD stage {no CKD: estimated glomerular filtration rate [eGFR] ≥60 mL/min/1.73 m2 and albuminuria [albumin:creatinine ratio (ACR)] <30 mg/g; stages G1-G3: eGFR ≥60 mL/min/1.73 m2 and ACR ≥30 mg/g or eGFR 30-59 mL/min/1.73 m2; stages G4 and G5: eGFR <30 mL/min/1.73 m2} and cognitive function using linear regression (objective measures) and logistic regression (SCD), accounting for sampling weights for nationally representative estimates. We tested whether associations differed by PA [Global Physical Activity Questionnaire, high PA ≥600 metabolic equivalent of task (MET) · min/week versus low PA <600 MET · min/week] using a Wald test. RESULTS: Among NHANES participants, 34.9% had CKD stages G1-G3, 2.6% had stages G4 and G5 and 50.7% had low PA. CKD stages G4 and G5 were associated with lower global cognitive function {difference = -0.38 standard deviation [SD] [95% confidence interval (CI) -0.62 to -0.15]}. This association differed by PA (Pinteraction = 0.01). Specifically, among participants with low PA, those with CKD stages G4 and G5 had lower global cognitive function [difference = -0.57 SD (95% CI -0.82 to -0.31)] compared with those without CKD. Among those with high PA, no difference was found [difference = 0.10 SD (95% CI -0.29-0.49)]. Similarly, the CKD stage was only associated with immediate recall, verbal fluency, executive function and processing speed among those with low PA; no associations were observed for delayed recall or self-perceived memory decline. CONCLUSIONS: CKD is associated with lower objective cognitive function among those with low but not high PA. Clinicians should consider screening older patients with CKD who have low PA for cognitive impairment and encourage them to meet PA guidelines.

Kidney Disease Symptoms before and after Kidney Transplantation.

BACKGROUND AND OBJECTIVES: Patients with kidney failure report a high symptom burden, which likely increases while on dialysis due to physical and mental stressors and decreases after kidney transplantation due to restoration of kidney function. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We leveraged a two-center prospective study of 1298 kidney transplant candidates and 521 recipients (May 2014 to March 2020). Symptom scores (0-100) at evaluation and admission for transplantation were calculated using the Kidney Disease Quality of Life Short-Form Survey, where lower scores represent greater burden, and burden was categorized as very high: 0.0-71.0; high: 71.1-81.0; medium: 81.1-91.0; and low: 91.1-100.0. We estimated adjusted waitlist mortality risk (competing risks regression), change in symptoms between evaluation and transplantation (n=190), and post-transplantation symptom score trajectories (mixed effects models). RESULTS: At evaluation, candidates reported being moderately to extremely bothered by fatigue (32%), xeroderma (27%), muscle soreness (26%), and pruritus (25%); 16% reported high and 21% reported very high symptom burden. Candidates with very high symptom burden were at greater waitlist mortality risk (adjusted subdistribution hazard ratio, 1.67; 95% confidence interval, 1.06 to 2.62). By transplantation, 34% experienced an increased symptom burden, whereas 42% remained unchanged. The estimated overall symptom score was 82.3 points at transplantation and 90.6 points at 3 months (10% improvement); the score increased 2.75 points per month (95% confidence interval, 2.38 to 3.13) from 0 to 3 months, and plateaued (-0.06 points per month; 95% confidence interval, -0.30 to 0.18) from 3 to 12 months post-transplantation. There were early (first 3 months) improvements in nine of 11 symptoms; pruritus (23% improvement) and fatigue (21% improvement) had the greatest improvements. CONCLUSIONS: Among candidates, very high symptom burden was associated with waitlist mortality, but for those surviving and undergoing kidney transplantation, symptoms improved.

The Risk of Postkidney Transplant Outcomes by Induction Choice Differs by Recipient Age.

BACKGROUND: Among adult kidney transplant (KT) recipients, the risk of post-KT adverse outcomes differs by type of induction immunosuppression. Immune response to induction differs as recipients age; yet, choice of induction is barely tailored by age likely due to a lack of evidence of the risks and benefits. METHODS: Using Scientific Registry of Transplant Recipients data, we identified 39336 first-time KT recipients (2010-2016). We estimated the length of stay (LOS), acute rejection (AR), graft failure, and death by induction type using logistic and Cox regression weighted by propensity score to adjust for confounders. We tested whether these estimates differed by age (65+ versus 18-64 y) using a Wald test. RESULTS: Overall, rabbit antithymocyte globulin (rATG) was associated with a decreased risk of AR (odds ratio = 0.79, 95% confidence interval [CI], 0.72-0.85) compared with basiliximab. The effect of induction on LOS and death (interaction P = 0.03 and 0.003) differed by recipient age. Discharge was on average 11% shorter in rATG among younger recipients (relative time = 0.89; 95% confidence interval [CI], 0.81-0.99) but not among older recipients (relative time = 1.01; 95% CI, 0.95-1.08). rATG was not associated with mortality among older (hazard ratio = 1.05; 95% CI, 0.96-1.15), but among younger recipients (hazard ratio = 0.87; 95% CI, 0.80-0.95), it was associated with reduced mortality risk. CONCLUSIONS: rATG should be considered to prevent AR, especially among recipients with high-immunologic risk regardless of age; however, choice of induction should be tailored to reduce LOS and risk of mortality, particularly among younger recipients.

Cognitive impairment burden in older and younger adults across the kidney transplant care continuum.

BACKGROUND: Younger kidney transplant (KT) candidates and recipients may have cognitive impairment due to chronic diseases and reliance on dialysis. METHODS: To quantify cognitive impairment burden by age across the KT care continuum, we leveraged a two-center cohort study of 3854 KT candidates at evaluation, 1114 recipients at admission, and 405 recipients at 1-year post-KT with measured global cognitive performance (3MS) or executive function (Trail Making Test). We also estimated burden of severe cognitive impairment that affects functional dependence (activities of daily living [ADL] < 6 or instrumental activities of daily living [IADL] < 8). RESULTS: Among KT candidates, global cognitive impairment (18-34 years: 11.1%; 35-49 years: 14.0%; 50-64 years: 19.5%; ≥65 years: 22.0%) and severe cognitive impairment burden (18-34 years: 1.1%; 35-49 years: 3.0%; 50-64 years: 6.2%; ≥65 years: 7.7%) increased linearly with age. Among KT recipients at admission, global cognitive impairment (18-34 years: 9.1%; 35-49 years: 6.1%; 50-64 years: 9.3%; ≥65 years: 15.7%) and severe cognitive impairment burden (18-34 years: 1.4%; 35-49 years: 1.4%; 50-64 years: 2.2%; ≥65 years: 4.6%) was lower. Despite lowest burden of cognitive impairment among KT recipients at 1-year post-KT across all ages (18-34 years: 1.7%; 35-49 years: 3.4%; 50-64 years: 4.3%; ≥65 years: 6.5%), many still exhibited severe cognitive impairment (18-34 years: .0%; 35-49 years: 1.9%; 50-64 years: 2.4%; ≥65 years: 3.5%). CONCLUSION: Findings were consistent for executive function impairment. While cognitive impairment increases with age, younger KT candidates have a high burden comparable to community-dwelling older adults, with some potentially suffering from severe forms. Transplant centers should consider routinely screening patients during clinical care encounters regardless of age.

Frailty-a risk factor of global and domain-specific cognitive decline among a nationally representative sample of community-dwelling older adult U.S. Medicare beneficiaries.

OBJECTIVES: frail older adults may be more vulnerable to stressors, resulting in steeper declines in cognitive function. Whether the frailty-cognition link differs by cognitive domain remains unclear; however, it could lend insight into underlying mechanisms. METHODS: we tested whether domain-specific cognitive trajectories (clock-drawing test, (CDT), immediate and delayed recall, orientation to date, time, president and vice-president naming) measured annually (2011-2016) differ by baseline frailty (physical frailty phenotype) in the National Health and Aging Trends Study (n = 7,439), a nationally representative sample of older adult U.S. Medicare beneficiaries, using mixed effects models to describe repeated measures of each cognitive outcome. To determine if the association between frailty and subsequent cognitive change differed by education, we tested for interaction using the Wald test. RESULTS: we observed steeper declines for frail compared to non-frail participants in each domain-specific outcome, except for immediate recall. Largest differences in slope were observed for CDT (difference = -0.12 (standard deviations) SD/year, 95%CI: -0.15, -0.08). By 2016, mean CDT scores for frail participants were 1.8 SD below the mean (95%CI: -1.99, -1.67); for non-frail participants, scores were 0.8 SD below the mean (95%CI: -0.89, -0.69). Associations differed by education for global cognitive function (Pinteraction < 0.001) and for each domain-specific outcome: CDT (Pinteraction < 0.001), orientation (Pinteraction < 0.001), immediate (Pinteraction < 0.001) and delayed (Pinteraction < 0.001) word recalls. CONCLUSION: frailty is associated with lower levels and steeper declines in cognitive function, with strongest associations for executive function. These findings suggest that aetiologies are multifactorial, though primarily vascular related; further research into its association with dementia sub-types and related pathologies is critical.

Pre-kidney transplant unintentional weight loss leads to worse post-kidney transplant outcomes.

BACKGROUND: Weight loss before kidney transplant (KT) is a known risk factor for weight gain and mortality, however, while unintentional weight loss is a marker of vulnerability, intentional weight loss might improve health. We tested whether pre-KT unintentional and intentional weight loss have differing associations with post-KT weight gain, graft loss and mortality. METHODS: Among 919 KT recipients from a prospective cohort study, we used adjusted mixed-effects models to estimate post-KT BMI trajectories, and Cox models to estimate death-uncensored graft loss, death-censored graft loss and all-cause mortality by 1-year pre-KT weight change category [stable weight (change ≤ 5%), intentional weight loss (loss > 5%), unintentional weight loss (loss > 5%) and weight gain (gain > 5%)]. RESULTS: The mean age was 53 years, 38% were Black and 40% were female. In the pre-KT year, 62% of recipients had stable weight, 15% had weight gain, 14% had unintentional weight loss and 10% had intentional weight loss. In the first 3 years post-KT, BMI increases were similar among those with pre-KT weight gain and intentional weight loss and lower compared with those with unintentional weight loss {difference +0.79 kg/m2/year [95% confidence interval (CI) 0.50-1.08], P < 0.001}. Only unintentional weight loss was independently associated with higher death-uncensored graft loss [adjusted hazard ratio (aHR) 1.80 (95% CI 1.23-2.62)], death-censored graft loss [aHR 1.91 (95% CI 1.12-3.26)] and mortality [aHR 1.72 (95% CI 1.06-2.79)] relative to stable pre-KT weight. CONCLUSIONS: This study suggests that unintentional, but not intentional, pre-KT weight loss is an independent risk factor for adverse post-KT outcomes.

Ambient Air Pollution and Mortality among Older Patients Initiating Maintenance Dialysis.

BACKGROUND: Fine particulate matter (particulate matter with diameter <2.5 µm [PM2.5]) is associated with CKD progression and may impact the health of patients living with kidney failure. While older (aged ≥65 years) adults are most vulnerable to the impact of PM2.5, it is unclear whether older patients on dialysis are at elevated risk of mortality when exposed to fine particulate matter. METHODS: Older adults initiating dialysis (2010-2016) were identified from US Renal Data System (USRDS). PM2.5 concentrations were obtained from NASA's Socioeconomic Data and Application Center (SEDAC) Global Annual PM2.5 Grids. We investigated the association between PM2.5 and all-cause mortality using Cox proportional hazard models with linear splines [knot at the current Environmental Protection Agency (EPA) National Ambient Air Quality Standard for PM2.5 of 12 µg/m3] and robust variance. RESULTS: For older dialysis patients who resided in areas with high PM2.5, a 10 µg/m3 increase in PM2.5 was associated with 1.16-fold (95% CI: 1.08-1.25) increased risk of mortality; furthermore, those who were female (aHR = 1.26, 95% CI: 1.13-1.42), Black (aHR = 1.31, 95% CI: 1.09-1.59), or had diabetes as a primary cause of kidney failure (aHR = 1.25, 95% CI: 1.13-1.38) were most vulnerable to high PM2.5. While the mortality risk associated with PM2.5 was stronger at higher levels (aHR = 1.19, 95% CI: 1.08-1.32), at lower levels (≤12 µg/m3), PM2.5 was significantly associated with mortality risk (aHR = 1.04, 95% CI: 1.00-1.07) among patients aged ≥75 years (Pslope difference = 0.006). CONCLUSIONS: Older adults initiating dialysis who resided in ZIP codes with PM2.5 levels >12 µg/m3 are at increased risk of mortality. Those aged >75 were at elevated risk even at levels below the EPA Standard for PM2.5.