Prospective Cohort Study Examining the Ability of Performance-Based and Self-Reported Frailty Measures to Predict 30-Day Rehospitalizations After Kidney Transplantation.

Performance-based measures of frailty are associated with healthcare utilization after kidney transplantation (KT) but require in-person assessment. A promising alternative is self-reported frailty. The goal of this study was to examine the ability of performance-based and self-reported frailty measures to predict 30-day rehospitalizations after KT. We conducted a prospective, observational cohort study involving 272 adults undergoing KT at Mayo Clinic in Minnesota, Florida, or Arizona. We simultaneously measured frailty before KT using the physical frailty phenotype (PFP), the short physical performance battery (SPPB), and self-report (the Patient-Reported Outcomes Measurement Information System [PROMIS] 4-item physical function short form v2.0). Both the PFP and self-reported frailty were independently associated with more than a 2-fold greater odds of 30-day rehospitalizations, while the SPPB was not. To our knowledge, this is the first study to assess the prognostic value of all three of the above frailty measures in patients undergoing KT. The PFP is more prognostic than the SPPB when assessing the risk of 30-day rehospitalizations; self-reported frailty can complement the PFP but not replace it. However, the 4-item survey assessing self-reported frailty represents a simple way to identify patients undergoing KT surgery who would benefit from interventions to lower the risk of rehospitalizations.

Iohexol plasma clearance measurement protocol standardization for adults: a consensus paper of the European Kidney Function Consortium.

International consensus supports the development of standardized protocols for measured glomerular filtration rate (mGFR) to facilitate the integration of mGFR testing in both clinical and research settings. To this end, the European Kidney Function Consortium convened an international group of experts with relevant experience in mGFR. The working group performed an extensive literature search to inform the development of recommendations for mGFR determination using 1-compartment plasma clearance models and iohexol as the exogenous filtration marker. Iohexol was selected as it is non-radio labeled, inexpensive, and safe, can be assayed at a central laboratory, and the other commonly used non-radio-labeled tracers have been (inulin) or are soon to be (iothalamate) discontinued. A plasma clearance model was selected over urine clearance as it requires no urine collection. A 1 compartment was preferred to 2 compartments as it requires fewer samples. The recommendations are based on published evidence complemented by expert opinion. The consensus paper covers practical advice for patients and health professionals, preparation, administration, and safety aspects of iohexol, laboratory analysis, blood sample collection and sampling times using both multiple and single-sample protocols, description of the mGFR mathematical calculations, as well as implementation strategies. Supplementary materials include patient and provider information sheets, standard operating procedures, a study protocol template, and support for mGFR calculation.

IFTA Foci Density: An Unrecognized Highly Prognostic Measurement of Fibrosis in Kidney Transplant Biopsies.

BACKGROUND: Contraction of interstitial fibrosis/tubular atrophy (IFTA) may cause %IFTA to under-represent the severity of nephron loss. Higher density of IFTA foci is an important predictor of progressive chronic kidney disease in native kidneys independent of %IFTA. METHODS: We studied kidney transplant recipients transplanted between 2000-2013 who had a 5-year surveillance kidney biopsy and subsequent follow-up. Banff ci score (interstitial fibrosis) was obtained from the pathology reports. After digitizing the biopsies, we traced cortex area and each distinct IFTA focus on a single trichrome-stained section. Percent IFTA area and IFTA foci density (count of IFTA foci/cortex area) were calculated. Cox models assessed the risk of death-censored graft failure after the 5-year biopsy with Banff ci score, morphometric %IFTA, and IFTA foci density. RESULTS: There were 58 death-censored allograft failures among 835 kidney recipients during the 5 years of follow-up. Biopsies from grafts that failed had higher mean Banff ci score (1.5 vs 0.7, p<0.0001), %IFTA (22.2% vs 7.0%, p<0.0001), and IFTA foci density (1.3 vs. 0.4 per mm2, p<0.001). After adjusting for other Banff scores or clinical variables, Banff ci did not correlate with allograft failure, but both higher %IFTA (HR=1.56, p<0.0001) and higher IFTA foci density (HR=2.34, p<0.001) did. All but 4 allograft failures by 10 years had biopsies in the top quartile of either %IFTA or IFTA foci density at 5 years. A model using just these two morphometric measures without clinical characteristics resulted in a c-statistic of 0.891 with respect to allograft failure. CONCLUSIONS: Morphometric characterization of IFTA foci density is a strong predictor of death censored allograft failure not captured in current Banff classification for grading of kidney fibrosis.

Consequences of low estimated glomerular filtration rate either before or early after kidney donation.

In the general population, decreases in glomerular filtration rate (GFR) are associated with subsequent development of chronic kidney disease (CKD), cardiovascular disease (CVD), and death. It is unknown if low estimated GFR (eGFR) before or early after kidney donation was also associated with these risks. One thousand six hundred ninety-nine living donors who had both predonation and early (4-10 weeks) postdonation eGFR were included. We studied the relationships between eGFR, age at donation, and the time to sustained eGFR<45 (CKD stage 3b) and <30 mL/min/1.73m2 (CKD stage 4), hypertension, diabetes mellitus (DM), CVD, and death. Median follow-up was 12 (interquartile range, 6-21) years. Twenty-year event rates were 5.8% eGFR<45 mL/min/1.73m2; 1.2% eGFR<30 mL/min/1.73m2; 29.0% hypertension; 7.8% DM; 8.0% CVD; and 5.2% death. The median time to eGFR<45 mL/min/1.73m2 (N = 79) was 17 years, and eGFR<30 mL/min/1.73m2 (N = 22) was 25 years. Both low predonation and early postdonation eGFR were associated with eGFR<45 mL/min/1.73m2 (P < .0001) and eGFR<30 mL/min/1.73m2 (P < .006); however, the primary driver of risk for all ages was low postdonation (rather than predonation) eGFR. Predonation and postdonation eGFR were not associated with hypertension, DM, CVD, or death. Low predonation and early postdonation eGFR are risk factors for developing eGFR<45 mL/min/1.73m2 (CKD stage 3b) and <30 mL/min/1.73m2 (CKD stage 4), but not CVD, hypertension, DM, or death.

End-Stage Kidney Disease After Partial and Radical Nephrectomy Among Patients with Severe Chronic Kidney Disease.

PURPOSE: AUA guidelines prioritize nephron sparing in patients with preexisting chronic kidney disease (CKD). However, few studies analyze long-term renal function in patients with preoperative severe CKD who undergo extirpative renal surgery. Herein, we compare the hazard of progression to end-stage kidney disease (ESKD) following partial nephrectomy (PN) and radical nephrectomy (RN) among patients with preoperative severe CKD. MATERIALS AND METHODS: Patients with stage 4 CKD who underwent PN or RN from 1970 to 2018 were identified. A multivariable Fine-Gray subdistribution hazard model was employed to assess associations with progression to ESKD accounting for the competing risk of death. RESULTS: A total of 186 patients with stage 4 CKD underwent PN (n = 71; 38%) or RN (n = 115; 62%) for renal neoplasms with median follow-up of 6.9 years (interquartile range 3.8-14.1). On multivariable analyses adjusting for competing risk of death, the subdistribution hazard ratio (SHR) for older age at surgery (SHR for 5-year increase 0.81; 95% CI 0.73-0.91; P < .001) and higher preoperative estimated glomerular filtration rate (SHR for 5-unit increase 0.63; 95% CI 0.47-0.84; P = .002) was associated with lower hazard of progression to ESKD. There was no significant difference in hazard of ESKD between PN and RN (SHR 0.82; 95% CI 0.50-1.33; P = .4). CONCLUSIONS: Among patients with preoperative severe CKD, higher preoperative estimated glomerular filtration rate was associated with lower hazard of progression to ESKD after extirpative surgery for renal neoplasms. We did not observe a significant difference in overall hazard for developing ESKD between PN and RN.

Living Kidney Donation: A Narrative Review of Mid- and Long-term Psychosocial Outcomes.

Living kidney donors make a significant contribution to alleviating the organ shortage. The aim of this article is to provide an overview of mid- and long-term (≥12 mo) living donor psychosocial outcomes and highlight areas that have been understudied and should be immediately addressed in both research and clinical practice. We conducted a narrative review by searching 3 databases. A total of 206 articles were included. Living donors can be divided into those who donate to an emotionally or genetically related person, the so-called directed donors, or to an emotionally or genetically unrelated recipient, the so-called nondirected donors. The most commonly investigated (bio)psychosocial outcome after living donation was health-related quality of life. Other generic (bio)psychological outcomes include specific aspects of mental health such as depression, and fatigue and pain. Social outcomes include financial and employment burdens and problems with insurance. Donation-specific psychosocial outcomes include regret, satisfaction, feelings of abandonment and unmet needs, and benefits of living kidney donation. The experience of living donation is complex and multifaceted, reflected in the co-occurrence of both benefits and burden after donation. Noticeably, no interventions have been developed to improve mid- or long-term psychosocial outcomes among living donors. We highlight areas for methodological improvement and identified 3 areas requiring immediate attention from the transplant community in both research and clinical care: (1) recognizing and providing care for the minority of donors who have poorer long-term psychosocial outcomes after donation, (2) minimizing donation-related financial burden, and (3) studying interventions to minimize long-term psychosocial problems.

Increased Pretransplant Inflammatory Biomarkers Predict Death With Function After Kidney Transplantation.

BACKGROUND: Chronic systemic inflammation is associated with mortality in patients with chronic kidney disease, cardiovascular disease, and diabetes. The goal of this study was to examine the relationship between pretransplant inflammatory biomarkers (growth differentiation factor-15 [GDF-15], interleukin-6 [IL-6], soluble tumor necrosis factor receptor-1, monokine induced by gamma interferon/chemokine [C-X-C motif] ligand 9 [MIG/CXCL9], monocyte chemoattractant protein-1, soluble FAS, tumor necrosis factor-α, interleukin-15, and interleukin-1ß) and death with function (DWF) after kidney transplantation (KT). METHODS: We retrospectively measured inflammatory biomarker levels in serum collected up to 1 y before KT (time from blood draw to KT was 130 ±â€…110 d) in recipients transplanted between January 2006 and December 2018. Kaplan-Meier estimation, Cox regression, and Gradient Boosting Machine modeling were used to examine the relationship between inflammatory biomarkers and DWF. RESULTS: Our cohort consisted of 1595 KT recipients, of whom 62.9% were male and 83.2% were non-Hispanic White. Over a mean follow-up of 7.4 ±â€…3.9 y, 21.2% of patients (n = 338) experienced DWF. Patients with the highest quartile levels of GDF-15 (>4766 pg/mL), IL-6 (>6.11 pg/mL), and MIG/CXCL9 (> 5835 pg/mL) had increased rates of DWF, and each predicted mortality independently of the others. When adjusted for clinical factors (age, diabetes, etc), the highest quartile levels of GDF-15 and IL-6 remained independently associated with DWF. Adding inflammatory markers to a clinical Cox model improved the C-statistic for DWF from 0.727 to 0.762 using a Gradient Boosting Machine modeling approach. CONCLUSIONS: These findings suggest that pre-KT serum concentrations of GDF-15, IL-6, and MIG/CXCL9 may help to risk stratify and manage patients undergoing KT and suggests that chronic inflammation may play a role in mortality in KT recipients.

Older Tissue Age Derived From Abdominal Computed Tomography Biomarkers of Muscle, Fat, and Bone Is Associated With Chronic Conditions and Higher Mortality.

OBJECTIVE: To determine whether body composition derived from medical imaging may be useful for assessing biologic age at the tissue level because people of the same chronologic age may vary with respect to their biologic age. METHODS: We identified an age- and sex-stratified cohort of 4900 persons with an abdominal computed tomography scan from January 1, 2010, to December 31, 2020, who were 20 to 89 years old and representative of the general population in Southeast Minnesota and West Central Wisconsin. We constructed a model for estimating tissue age that included 6 body composition biomarkers calculated from abdominal computed tomography using a previously validated deep learning model. RESULTS: Older tissue age associated with intermediate subcutaneous fat area, higher visceral fat area, lower muscle area, lower muscle density, higher bone area, and lower bone density. A tissue age older than chronologic age was associated with chronic conditions that result in reduced physical fitness (including chronic obstructive pulmonary disease, arthritis, cardiovascular disease, and behavioral disorders). Furthermore, a tissue age older than chronologic age was associated with an increased risk of death (hazard ratio, 1.56; 95% CI, 1.33 to 1.84) that was independent of demographic characteristics, county of residency, education, body mass index, and baseline chronic conditions. CONCLUSION: Imaging-based body composition measures may be useful in understanding the biologic processes underlying accelerated aging.

Morphometric analysis of chronicity on kidney biopsy: a useful prognostic exercise.

Chronic changes on kidney biopsy specimens include increasing amounts of arteriosclerosis, glomerulosclerosis, interstitial fibrosis and tubular atrophy, enlarged nephron size, and reduced nephron number. These chronic changes are difficult to accurately assess by visual inspection but are reasonably quantified using morphometry. This review describes the various patient populations that have undergone morphometric analysis of kidney biopsies. The common approaches to morphometric analysis are described. The chronic kidney disease outcomes associated with various chronic changes by morphometry are also summarized. Morphometry enriches the characterization of chronicity on a kidney biopsy and this can supplement the pathologist's diagnosis. Artificial intelligence image processing tools are needed to automate the annotations needed for practical morphometric analysis of kidney biopsy specimens in routine clinical care.

Abdominal Body Composition Reference Ranges and Association With Chronic Conditions in an Age- and Sex-Stratified Representative Sample of a Geographically Defined American Population.

BACKGROUND: Body composition can be accurately quantified from abdominal computed tomography (CT) exams and is a predictor for the development of aging-related conditions and for mortality. However, reference ranges for CT-derived body composition measures of obesity, sarcopenia, and bone loss have yet to be defined in the general population. METHODS: We identified a population-representative sample of 4 900 persons aged 20 to 89 years who underwent an abdominal CT exam from 2010 to 2020. The sample was constructed using propensity score matching an age and sex stratified sample of persons residing in the 27-county region of Southern Minnesota and Western Wisconsin. The matching included race, ethnicity, education level, region of residence, and the presence of 20 chronic conditions. We used a validated deep learning based algorithm to calculate subcutaneous adipose tissue area, visceral adipose tissue area, skeletal muscle area, skeletal muscle density, vertebral bone area, and vertebral bone density from a CT abdominal section. RESULTS: We report CT-based body composition reference ranges on 4 649 persons representative of our geographic region. Older age was associated with a decrease in skeletal muscle area and density, and an increase in visceral adiposity. All chronic conditions were associated with a statistically significant difference in at least one body composition biomarker. The presence of a chronic condition was generally associated with greater subcutaneous and visceral adiposity, and lower muscle density and vertebrae bone density. CONCLUSIONS: We report reference ranges for CT-based body composition biomarkers in a population-representative cohort of 4 649 persons by age, sex, body mass index, and chronic conditions.

Association of Kidney Cysts With Progressive CKD After Radical Nephrectomy.

RATIONALE & OBJECTIVE: Simple kidney cysts, which are common and usually considered of limited clinical relevance, are associated with older age and lower glomerular filtration rate (GFR), but little has been known of their association with progressive chronic kidney disease (CKD). STUDY DESIGN: Observational cohort study. SETTING & PARTICIPANTS: Patients with presurgical computed tomography or magnetic resonance imaging who underwent a radical nephrectomy for a tumor; we reviewed the retained kidney images to characterize parenchymal cysts at least 5mm in diameter according to size and location. EXPOSURE: Parenchymal cysts at least 5mm in diameter in the retained kidney. Cyst characteristics were correlated with microstructural findings on kidney histology. OUTCOME: Progressive CKD defined by dialysis, kidney transplantation, a sustained≥40% decline in eGFR for at least 3 months, or an eGFR<10mL/min/1.73m2 that was at least 5mL/min/1.73m2 below the postnephrectomy baseline for at least 3 months. ANALYTICAL APPROACH: Cox models assessed the risk of progressive CKD. Models adjusted for baseline age, sex, body mass index, hypertension, diabetes, eGFR, proteinuria, and tumor volume. Nonparametric Spearman's correlations were used to examine the association of the number and size of the cysts with clinical characteristics, kidney function, and kidney volumes. RESULTS: There were 1,195 patients with 50 progressive CKD events over a median 4.4 years of follow-up evaluation. On baseline imaging, 38% had at least 1 cyst, 34% had at least 1 cortical cyst, and 8.7% had at least 1 medullary cyst. A higher number of cysts was associated with progressive CKD and was modestly correlated with larger nephrons and more nephrosclerosis on kidney histology. The number of medullary cysts was more strongly associated with progressive CKD than the number of cortical cysts. LIMITATIONS: Patients who undergo a radical nephrectomy may differ from the general population. A radical nephrectomy may accelerate the risk of progressive CKD. Genetic testing was not performed. CONCLUSIONS: Cysts in the kidney, particularly the medulla, should be further examined as a potentially useful imaging biomarker of progressive CKD beyond the current clinical evaluation of kidney function and common CKD risk factors. PLAIN-LANGUAGE SUMMARY: Kidney cysts are common and often are considered of limited clinical relevance despite being associated with lower glomerular filtration rate. We studied a large cohort of patients who had a kidney removed due to a tumor to determine whether cysts in the retained kidney were associated with kidney health in the future. We found that more cysts in the kidney and, in particular, cysts in the deepest tissue of the kidney (the medulla) were associated with progressive kidney disease, including kidney failure where dialysis or a kidney transplantation is needed. Patients with cysts in the kidney medulla may benefit from closer monitoring.

Kidney cortex shear wave motion simulations based on segmented biopsy histology.

BACKGROUND AND OBJECTIVE: Biopsy stands as the gold standard for kidney transplant assessment, yet its invasive nature restricts frequent use. Shear wave elastography (SWE) is emerging as a promising alternative for kidney transplant monitoring. A parametric study involving 12 biopsy data sets categorized by standard biopsy scores (3 with normal histology, 3 with interstitial inflammation (i), 3 with interstitial fibrosis (ci), and 3 with tubular atrophy (ct)), was conducted to evaluate the interdependence between microstructural variations triggered by chronic allograft rejection and corresponding alterations in SWE measurements. METHODS: Heterogeneous shear wave motion simulations from segmented kidney cortex sections were performed employing the staggered-grid finite difference (SGFD) method. The SGFD method allows the mechanical properties to be defined on a pixel-basis for shear wave motion simulation. Segmentation techniques enabled the isolation of four histological constituents: glomeruli, tubules, interstitium, and fluid. Baseline ex vivo Kelvin-Voigt mechanical properties for each constituent were drawn from established literature. The parametric evaluation was then performed by altering the baseline values individually. Shear wave velocity dispersion curves were measured with the generalized Stockwell transform in conjunction with slant frequency-wavenumber analysis (GST-SFK) algorithm. By fitting the curve within the 100-400 Hz range to the Kelvin-Voigt model, the rheological parameters, shear elasticity (µ1) and viscosity (µ2), were estimated. A time-to-peak algorithm was used to estimate the group velocity. The resultant in silico models emulated the heterogeneity of kidney cortex within the shear wave speed (SWS) reconstructions. RESULTS: The presence of inflammation showed considerable spatial composition disparities compared to normal cases, featuring a 23 % increase in interstitial area and a 19 % increase in glomerular area. Concomitantly, there was a reduction of 12 % and 47 % in tubular and fluid areas, respectively. Consequently, mechanical changes induced by inflammation predominate in terms of rheological differentiation, evidenced by increased elasticity and viscosity. Mild tubular atrophy showed significant elevation in group velocity and µ1. Conversely, mild and moderate fibrosis exhibited negligible alterations across all parameters, compatible with relatively limited morphological impact. CONCLUSIONS: This proposed model holds promise in enabling patient-specific simulations of the kidney cortex, thus facilitating exploration into how pathologies altering cortical morphology correlates to modifications in SWE-derived rheological measurements. We demonstrated that inflammation caused substantial changes in measured mechanical properties.

Development and validation of a model to predict acute kidney injury following high-dose methotrexate in patients with lymphoma.

STUDY OBJECTIVE: To develop and validate a model for predicting acute kidney injury (AKI) after high-dose methotrexate (HDMTX) exposure. DESIGN: Retrospective analysis. SETTING: Multisite integrated health system throughout Minnesota and Wisconsin. PATIENTS: Adult patients with lymphoma who received HDMTX as a 4-h infusion. MEASUREMENTS AND MAIN RESULTS: LASSO methodology was used to identify factors available at the outset of therapy that predicted incident AKI within 7 days following HDMTX. The model was then validated in an independent cohort. The incidence of AKI within 7 days following HDMTX was 21.6% (95% confidence interval (CI) 18.4%-24.8%) in the derivation cohort (435 unique patients who received a total of 1642 doses of HDMTX) and 15.6% (95% CI 5.3%-24.8%) in the validation cohort (55 unique patients who received a total of 247 doses of HDMTX). Factors significantly associated with AKI after HDMTX in the multivariable model included age ≥ 55 years, male sex, and lower HDMTX dose number. Other factors that were not found to be significantly associated with AKI on multivariable analysis, but were included in the final model, were body surface area, Charlson Comorbidity Index, and estimated glomerular filtration rate. The c-statistic of the model was 0.72 (95% CI 0.69-0.75) in the derivation cohort and 0.72 (95% CI 0.60-0.84) in the validation cohort. CONCLUSION: This model utilizing identified sociodemographic and clinical factors is predictive of AKI following HDMTX administration in adult patients with lymphoma.

Performance of the European Kidney Function Consortium (EKFC) creatinine-based equation in United States cohorts.

Estimating glomerular filtration rate (GFR) is important in daily practice to assess kidney function and adapting the best clinical care of patients with and without chronic kidney disease. The new creatinine-based European Kidney Function Consortium (EKFC) equation is used to estimate GFR. This equation was developed and validated mainly in European individuals and based on a rescaled creatinine, with the rescaling factor (Q-value) defined as the median normal value of serum creatinine in a given population. The validation was limited in Non-Black Americans and absent in Black Americans. Here, our cross-sectional analysis included 12,854 participants from nine studies encompassing large numbers of both non-Black and Black Americans with measured GFR by clearance of an exogenous marker (reference method), serum creatinine, age, sex, and self-reported race available. Two strategies were considered with population-specific Q-values in Black and non-Black men and women (EKFCPS) or a race-free Q-value (EKFCRF). In the whole population, only the EKFCPS equation showed no statistical median bias (0.14, 95% confidence interval [-0.07; 0.35] mL/min/1.73m2), and the bias for the EKFCRF (0.74, [0.51; 0.94] mL/min/1.73m2) was closer to zero than that for the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI2021) equation (1.22, [0.99; 1.47]) mL/min/1.73m2]. The percentage of estimated GFR within 30% of measured GFR was similar for CKD-EPI2021 (79.2% [78.5%; 79.9%]) and EKFCRF (80.1% [79.4%; 80.7%]), but improved for the EKFCPS equation (81.1% [80.5%; 81.8%]). Thus, our EKFC equations can be used to estimate GFR in the United States incorporating either self-reported race or unknown race at the patient's discretion per hospital registration records.