High-risk adverse drug reactions: consideration of limited dialysis therapy for toxic epidermal necrolysis (TEN)

Toxic epidermal necrolysis (TEN) is a rare but often lethal drug reaction involving the skin. Treatment is often centered around suppurative care, and the mortality rate remains unacceptably high, although the clinical and epidemiological features of TEN have been well documented for decades. Recent studies have placed an emphasis on certain medications in the pathophysiology of severe TEN, and our colleagues previously reported several cases of clinical improvement in TEN patients following hemodialysis. Here, we discuss the major considerations for initiating dialysis in TEN patients. By doing so, we hope to encourage others to explore this potential avenue for treating TEN, one of the most serious medical emergencies in the field of dermatology.

Renal MRI: From Nephron to NMR Signal

Renal diseases pose a significant socio-economic burden on healthcare systems. The development of better diagnostics and prognostics is well-recognized as a key strategy to resolve these challenges. Central to these developments are MRI biomarkers, due to their potential for monitoring of early pathophysiological changes, renal disease progression or treatment effects. The surge in renal MRI involves major cross-domain initiatives, large clinical studies, and educational programs. In parallel with these translational efforts, the need for greater (patho)physiological specificity remains, to enable engagement with clinical nephrologists and increase the associated health impact. The ISMRM 2022 Member Initiated Symposium (MIS) on renal MRI spotlighted this issue with the goal of inspiring more solutions from the ISMRM community. This work is a summary of the MIS presentations devoted to: 1) educating imaging scientists and clinicians on renal (patho)physiology and demands from clinical nephrologists, 2) elucidating the connection of MRI parameters with renal physiology, 3) presenting the current state of leading MR surrogates in assessing renal structure and functions as well as their next generation of innovation, and 4) describing the potential of these imaging markers for providing clinically meaningful renal characterization to guide or supplement clinical decision making. We hope to continue momentum of recent years and introduce new entrants to the development process, connecting (patho)physiology with (bio)physics, and conceiving new clinical applications. We envision this process to benefit from cross-disciplinary collaboration and analogous efforts in other body organs, but also to maximally leverage the unique opportunities of renal physiology. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 2.

Examining the safety and effectiveness of a 4-week supervised exercise intervention in the treatment of frailty in patients with chronic kidney disease

Background

The optimal duration of antifrailty interventions and how best to deliver them to patients with chronic kidney disease (CKD) is unknown. The aim of this study was to examine the safety, feasibility and preliminary efficacy of a 4-week supervised exercise intervention on frailty in patients with CKD.

Methods

We conducted a prospective feasibility study involving patients with ≥stage 3 CKD (1 patient with stage 3 CKD, 7 patients with stage 4 CKD and 17 patients with stage 5 CKD) who were either frail or prefrail according to the physical frailty phenotype and/or had a Short Physical Performance Battery (SPPB) score ≤10. The exercise intervention consisted of two supervised outpatient sessions per week for 4 weeks (eight total sessions). Frailty and other study measures were assessed at baseline and after 4 weeks of exercise.

Results

Of the 34 participants who completed the baseline assessment and were included in the analyses, 25 (73.5%) completed the 4-week assessment. Overall, 64.0% of patients were on dialysis and 64.0% had diabetes mellitus. After 4 weeks of exercise, frailty prevalence, total SPPB scores and energy/fatigue scores improved. No adverse study-related outcomes were reported.

Conclusions

The 4 weeks of supervised exercise was safe, was associated with an excellent completion rate and improved frailty parameters in CKD patients with CKD. This study provides important preliminary data for a future larger prospective randomized study.

Clinical Trialgov

registration: NCT03535584.

Kidney Outcomes Following Utilization of Molecular Adsorbent Recirculating System

Introduction

Molecular adsorbent recirculating system (MARS) is an extracorporeal system combining conventional veno-venous hemodiafiltration and adsorption to provide rescue support in fulminant hepatic failure. Acute kidney injury (AKI) is common in patients with hepatic failure warranting continuous kidney replacement therapy (CKRT). Our primary aim was to characterize a cohort of patients who received MARS therapy and examine kidney events given the current paucity of available data.

Methods

Patients initiating MARS in a tertiary care setting from January 2014 through December 2020 were assessed for treatment indications, transplantation, CKRT, kidney recovery, and death. Data was collected using the REDCAP software.

Results

A total of 49 patients (67% female; 75% White) received MARS therapy with 29 patients (59%) requiring concomitant CKRT. Hepatic encephalopathy (HE) was the most common indication for MARS initiation (55%). In-hospital mortality was 41% (12/29) among patients who received CKRT versus 10% (2/20) among those not requiring CKRT (relative risk [RR] 4.15, 95% confidence interval [CI] 1.04 to 16.52, P = 0.044); this persisted following adjustment for prespecified patient characteristics (all RR ≥ 3.76, all P ≤ 0.060). One-year mortality post-MARS initiation was high overall but highest among the CKRT group (59% [17/29] vs. 25% [5/20] unadjusted RR 2.92, 95% CI 1.08 to 7.94, P = 0.035). Liver transplant after MARS occurred in 41% of patients (20/49). After CKRT, 39% of patients (9/29) recovered kidney function prior to hospital discharge.

Conclusions

Patients requiring MARS frequently have AKI warranting the use of concomitant CKRT, which is associated with a high rate of in-hospital and 1-year mortality.

Cellular Senescence and Frailty in Transplantation

Purpose of review

To summarizes the literature on cellular senescence and frailty in solid-organ transplantation and highlight the emerging role of senotherapeutics as a treatment for cellular senescence.

Recent findings

Solid-organ transplant patients are aging. Many factors contribute to aging acceleration in this population, including cellular senescence. Senescent cells accumulate in tissues and secrete proinflammatory and profibrotic proteins which result in tissue damage. Cellular senescence contributes to age-related diseases and frailty. Our understanding of the role cellular senescence plays in transplant-specific complications such as allograft immunogenicity and infections is expanding. Promising treatments, including senolytics, senomorphics, cell-based regenerative therapies, and behavioral interventions, may reduce cellular senescence abundance and frailty in patients with solid-organ transplants.

Summary

Cellular senescence and frailty contribute to adverse outcomes in solid-organ transplantation. Continued pursuit of understanding the role cellular senescence plays in transplantation may lead to improved senotherapeutic approaches and better graft and patient outcomes.

Diabetic kidney disease induces transcriptome alterations associated with angiogenesis activity in human mesenchymal stromal cells

BACKGROUND

Therapeutic interventions that optimize angiogenic activities may reduce rates of end-stage kidney disease, critical limb ischemia, and lower extremity amputations in individuals with diabetic kidney disease (DKD). Infusion of autologous mesenchymal stromal cells (MSC) is a promising novel therapy to rejuvenate vascular integrity. However, DKD-related factors, including hyperglycemia and uremia, might alter MSC angiogenic repair capacity in an autologous treatment approach.

METHODS

To explore the angiogenic activity of MSC in DKD, the transcriptome of adipose tissue-derived MSC obtained from DKD subjects was compared to age-matched controls without diabetes or kidney impairment. Next-generation RNA sequencing (RNA-seq) was performed on MSC (DKD n = 29; Controls n = 9) to identify differentially expressed (DE; adjusted p < 0.05, |log₂fold change|> 1) messenger RNA (mRNA) and microRNA (miRNA) involved in angiogenesis (GeneCards). Paracrine-mediated angiogenic repair capacity of MSC conditioned medium (MSCcm) was assessed in vitro using human umbilical vein endothelial cells incubated in high glucose and indoxyl sulfate for a hyperglycemic, uremic state.

RESULTS

RNA-seq analyses revealed 133 DE mRNAs (77 upregulated and 56 down-regulated) and 208 DE miRNAs (119 up- and 89 down-regulated) in DKD-MSC versus Control-MSC. Interestingly, miRNA let-7a-5p, which regulates angiogenesis and participates in DKD pathogenesis, interacted with 5 angiogenesis-associated mRNAs (transgelin/TAGLN, thrombospondin 1/THBS1, lysyl oxidase-like 4/LOXL4, collagen 4A1/COL4A1 and collagen 8A1/COL8A1). DKD-MSCcm incubation with injured endothelial cells improved tube formation capacity, enhanced migration, reduced adhesion molecules E-selectin, vascular cell adhesion molecule 1 and intercellular adhesion molecule 1 mRNA expression in endothelial cells. Moreover, angiogenic repair effects did not differ between treatment groups (DKD-MSCcm vs. Control-MSCcm).

CONCLUSIONS

MSC from individuals with DKD show angiogenic transcriptome alterations compared to age-matched controls. However, angiogenic repair potential may be preserved, supporting autologous MSC interventions to treat conditions requiring enhanced angiogenic activities such as DKD, diabetic foot ulcers, and critical limb ischemia.

Measuring copeptin, a surrogate for vasopressin in patients with hypertension - Can it identify those who are volume Responsive?

BACKGROUND

Among hypertensive patients, plasma renin activity is lower and the response to diuretic monotherapy greater in volume responsive hypertensive patients. We hypothesized that hormones influencing extracellular volume such as vasopressin / antidiuretic hormone (ADH) might permit the development of a simple test to identify those with volume-related hypertension. Such a test might be of particular benefit to the Black population which is purported to have a higher incidence of volume-related and responsive hypertension. Thus, using copeptin, a surrogate marker for ADH, we studied if there were differences in this hormone between those with and without volume responsive hypertension.

METHODS

Serum copeptin was measured in biobanked blood samples from the Genetic Epidemiology of Responses to Antihypertensives (GERA) I study and analyzed with other variables from the study dataset.

RESULTS

There was no relationship between PRA and copeptin values nor could the response in blood pressure be predicted by the copeptin values. However, baseline copeptin levels were higher in Black than in White subjects (7.5 pmol/L vs 5.4 pmol/L, P < 0.001) while plasma sodium and calculated plasma osmolality were slightly lower in keeping with the concept that Black subjects have more volume-related hypertension. In addition, after hydrochlorothiazide (HCTZ), copeptin was significantly lower in Black (6.2 pmol/L, P = 0.004) but unchanged in White subjects (5.2 pmol/L, P = 0.901) and there were also changes in sodium.

CONCLUSION

The current study suggests differences in ADH physiology between hypertensive Black and White patients. However, the use of copeptin to identify volume responsive patients could not be confirmed.

Cellular senescence: the good, the bad and the unknown

Cellular senescence is a ubiquitous process with roles in tissue remodelling, including wound repair and embryogenesis. However, prolonged senescence can be maladaptive, leading to cancer development and age-related diseases. Cellular senescence involves cell-cycle arrest and the release of inflammatory cytokines with autocrine, paracrine and endocrine activities. Senescent cells also exhibit morphological alterations, including flattened cell bodies, vacuolization and granularity in the cytoplasm and abnormal organelles. Several biomarkers of cellular senescence have been identified, including SA-βgal, p16 and p21; however, few markers have high sensitivity and specificity. In addition to driving ageing, senescence of immune and parenchymal cells contributes to the development of a variety of diseases and metabolic disorders. In the kidney, senescence might have beneficial roles during development and recovery from injury, but can also contribute to the progression of acute kidney injury and chronic kidney disease. Therapies that target senescence, including senolytic and senomorphic drugs, stem cell therapies and other interventions, have been shown to extend lifespan and reduce tissue injury in various animal models. Early clinical trials confirm that senotherapeutic approaches could be beneficial in human disease. However, larger clinical trials are needed to translate these approaches to patient care.

Cardiovascular Outcomes in Kidney Transplant Recipients With ADPKD

Introduction

Cardiovascular disease leads to high morbidity and mortality in patients with kidney failure. Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a systemic disease with various cardiac abnormalities. Details on the cardiovascular profile of patients with ADPKD who are undergoing kidney transplantation (KT) and its progression are limited.

Methods

Echocardiographic data within 2 years before KT (1993-2020), and major adverse cardiovascular events (MACEs) after transplantation were retrieved. The primary outcome is to assess cardiovascular abnormalities on echocardiography at the time of transplantation in ADPKD as compared with patients without ADPKD matched by sex (male, 59.4%) and age at transplantation (57.2 ± 8.8 years).

Results

Compared with diabetic nephropathy (DN, n = 271) and nondiabetic, patients without ADPKD (NDNA) (n = 271) at the time of KT, patients with ADPKD (n = 271) had lower rates of left ventricular hypertrophy (LVH) (39.4% vs. 66.4% vs. 48.6%), mitral (2.7% vs. 6.3% vs. 7.45) and tricuspid regurgitations (1.8% vs. 6.6% vs. 7.2%). Patients with ADPKD had less diastolic (25.3%) and systolic (5.6%) dysfunction at time of transplantation. Patients with ADPKD had the most favorable post-transplantation survival (median 18.7 years vs. 12.0 for diabetic nephropathy [DN] and 13.8 years for nondiabetic non-ADPKD [NDNA]; P < 0.01) and the most favorable MACE-free survival rate (hazard ratio = 0.51, P < 0.001). Patients with ADPKD had worsening of their valvular function and an increase in the sinus of Valsalva diameter post-transplantation (38.2 vs. 39.9 mm, P < 0.01).

Conclusion

ADPKD transplant recipients have the most favorable cardiac profile pretransplantation with better patient survival and MACE-free survival rates but worsening valvular function and increasing sinus of Valsalva diameter, as compared with patients with other kidney diseases.

A new gene set identifies senescent cells and predicts senescence-associated pathways across tissues

Although cellular senescence drives multiple age-related co-morbidities through the senescence-associated secretory phenotype, in vivo senescent cell identification remains challenging. Here, we generate a gene set (SenMayo) and validate its enrichment in bone biopsies from two aged human cohorts. We further demonstrate reductions in SenMayo in bone following genetic clearance of senescent cells in mice and in adipose tissue from humans following pharmacological senescent cell clearance. We next use SenMayo to identify senescent hematopoietic or mesenchymal cells at the single cell level from human and murine bone marrow/bone scRNA-seq data. Thus, SenMayo identifies senescent cells across tissues and species with high fidelity. Using this senescence panel, we are able to characterize senescent cells at the single cell level and identify key intercellular signaling pathways. SenMayo also represents a potentially clinically applicable panel for monitoring senescent cell burden with aging and other conditions as well as in studies of senolytic drugs.

Older Patients with Advanced Chronic Kidney Disease and Their Perspectives on Prognostic Information: a Qualitative Study

BACKGROUND

Prognostic information is key to shared decision-making, particularly in life-limiting illness like advanced chronic kidney disease (CKD).

OBJECTIVE

To understand the prognostic information preferences expressed by older patients with CKD.

DESIGN AND PARTICIPANTS

Qualitative study of 28 consecutively enrolled patients over 65 years of age with non-dialysis dependent CKD stages 3b-5, receiving care in a multi-disciplinary CKD clinic.

APPROACH

Semi-structured telephone or in-person interviews to explore patients' preference for and perceived value of individualized prognostic information. Interviews were analyzed using inductive content analysis.

KEY RESULTS

We completed interviews with 28 patients (77.7 ± SD 6.8 years, 69% men). Patients varied in their preference for prognostic information and more were interested in their risk of progression to end-stage kidney disease (ESKD) than in life expectancy. Many conflated ESKD risk with risk of death, perceiving a binary choice between dialysis and quick decline and death. Patients expressed that prognostic information would allow them to plan, take care of important business, and think about their treatment options. Patients were accepting of prognostic uncertainty and imagined leveraging it to nurture hope or motivate them to better manage risk factors. They endorsed the desire to receive prognosis of life expectancy even though it may be hard to accept or difficult to talk about but worried it could create helplessness for other patients in their situation.

CONCLUSION

Most, but not all, patients were interested in prognostic information and could see its value in motivating behavior change and allowing planning. Some patients expressed concern that information on life expectancy might cause depression and hopelessness. Therefore, prognostic information is most appropriate as part of a clinical conversation that fosters shared decision-making and helps patients consider treatment risks, benefits, and burdens in context of their lives.

Telehealth versus face-to-face visits: A comprehensive outpatient perspective-based cohort study of patients with kidney disease

Background

Telenephrology has become an important health care delivery modality during the COVID-19 pandemic. However, little is known about patient perspectives on the quality of care provided via telenephrology compared to face-to-face visits. We aimed to use objective data to study patients’ perspectives on outpatient nephrology care received via telenephrology (phone and video) versus face-to-face visits.

Methods

We retrospectively studied adults who received care in the outpatient Nephrology & Hypertension division at Mayo Clinic, Rochester, from March to July 2020. We used a standardized survey methodology to evaluate patient satisfaction. The primary outcome was the percent of patients who responded with a score of good (4) or very good (5) on a 5-point Likert scale on survey questions that asked their perspectives on access to their nephrologist, relationship with care provider, their opinions on the telenephrology technology, and their overall assessment of the care received. Wilcoxon rank sum tests and chi-square tests were used as appropriate to compare telenephrology versus face-to-face visits.

Results

3,486 of the patient encounters were face-to-face, 808 phone and 317 video visits. 443 patients responded to satisfaction surveys, and 21% of these had telenephrology encounters. Established patients made up 79.6% of telenephrology visits and 60.9% of face-to-face visits. There was no significant difference in patient perceived access to health care, satisfaction with their care provider, or overall quality of care between patients cared for via telenephrology versus face-to-face. Patient satisfaction was also equally high.

Conclusions

Patient satisfaction was equally high amongst those patients seen face-to-face or via telenephrology.

Dialysis Initiation in Patients With Chronic Coronary Disease and Advanced Chronic Kidney Disease in ISCHEMIA-CKD

Background In participants with concomitant chronic coronary disease and advanced chronic kidney disease (CKD), the effect of treatment strategies on the timing of dialysis initiation is not well characterized. Methods and Results In ISCHEMIA-CKD (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches-Chronic Kidney Disease), 777 participants with advanced CKD and moderate or severe ischemia were randomized to either an initial invasive or conservative management strategy. Herein, we compare the proportion of randomized participants with non-dialysis-requiring CKD at baseline (n=362) who initiated dialysis and compare the time to dialysis initiation between invasive versus conservative management arms. Using multivariable Cox regression analysis, we also sought to identify the effect of invasive versus conservative chronic coronary disease management strategies on dialysis initiation. At a median follow-up of 23 months (25th-75th interquartile range, 14-32 months), dialysis was initiated in 18.9% of participants (36/190) in the invasive strategy and 16.9% of participants (29/172) in the conservative strategy (P=0.22). The median time to dialysis initiation was 6.0 months (interquartile range, 3.0-16.0 months) in the invasive group and 18.2 months (interquartile range, 12.2-25.0 months) in the conservative group (P=0.004), with no difference in procedural acute kidney injury rates between the groups (7.8% versus 5.4%; P=0.26). Baseline clinical factors associated with earlier dialysis initiation were lower baseline estimated glomerular filtration rate (hazard ratio [HR] associated with 5-unit decrease, 2.08 [95% CI, 1.72-2.56]; P<0.001), diabetes (HR, 2.30 [95% CI, 1.28-4.13]; P=0.005), hypertension (HR, 7.97 [95% CI, 1.09-58.21]; P=0.041), and Hispanic ethnicity (HR, 2.34 [95% CI, 1.22-4.47]; P=0.010). Conclusions In participants with non-dialysis-requiring CKD in ISCHEMIA-CKD, randomization to an invasive chronic coronary disease management strategy (relative to a conservative chronic coronary disease management strategy) is associated with an accelerated time to initiation of maintenance dialysis for kidney failure. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT01985360.

Frailty in CKD and Transplantation

The population is aging. Although older adults have higher rates of comorbidities and adverse health events, they represent a heterogeneous group with different health trajectories. Frailty, a clinical syndrome of decreased physiological reserve and increased susceptibility to illness and death, has emerged as a potential risk stratification tool in older patients with chronic kidney disease (CKD). Frailty is commonly observed in patients with CKD and associated with numerous adverse outcomes, including falls, decreased quality of life, hospitalizations, and death. Multiple pathologic factors contribute to the development of frailty in patients with CKD, including biological mechanisms of aging and physiological dysregulation. Current interventions to reduce frailty are promising, but additional investigations are needed to determine whether optimizing frailty measures improves renal and overall health outcomes. This review of frailty in CKD examines frailty definitions, the impact of frailty on health outcomes across the CKD spectrum, mechanisms of frailty, and antifrailty interventions (e.g., exercise or senescent cell clearance) tested in CKD patients. In addition, existing knowledge gaps, limitations of current frailty definitions in CKD, and challenges surrounding effective antifrailty strategies in CKD are considered.

Progressive Cellular Senescence Mediates Renal Dysfunction in Ischemic Nephropathy

BACKGROUND

Peripheral vascular diseases may induce chronic ischemia and cellular injury distal to the arterial obstruction. Cellular senescence involves proliferation arrest in response to stress, which can damage neighboring cells. Renal artery stenosis (RAS) induces stenotic-kidney dysfunction and injury, but whether these arise from cellular senescenceand their temporal pattern remain unknown.

METHODS

Chronic renal ischemia was induced in transgenic INK-ATTAC and wild type C57BL/6 mice by unilateral RAS, and kidney function (in vivo micro-MRI) and tissue damage were assessed. Mouse healthy and stenotic kidneys were analyzed using unbiased single-cell RNA-sequencing. To demonstrate translational relevance, cellular senescence was studied in human stenotic kidneys.

RESULTS

Using intraperitoneal AP20187 injections starting 1, 2, or 4 weeks after RAS, selective clearance of cells highly expressing p16^Ink4a attenuated cellular senescence and improved stenotic-kidney function; however, starting treatment immediately after RAS induction was unsuccessful. Broader clearance of senescent cells, using the oral senolytic combination dasatinib and quercetin, in C57BL/6 RAS mice was more effective in clearing cells positive for p21 (Cdkn1a) and alleviating renal dysfunction and damage. Unbiased, single-cell RNA sequencing in freshly dissociated cells from healthy and stenotic mouse kidneys identified stenotic-kidney epithelial cells undergoing both mesenchymal transition and senescence. As in mice, injured human stenotic kidneys exhibited cellular senescence, suggesting this process is conserved.

CONCLUSIONS

Maladaptive tubular cell senescence, involving upregulated p16 (Cdkn2a), p19 (Cdkn2d), and p21 (Cdkn1a) expression, is associated with renal dysfunction and injury in chronic ischemia. These findings support development of senolytic strategies to delay chronic ischemic renal injury.

Diabetic Kidney Disease Alters the Transcriptome and Function of Human Adipose-Derived Mesenchymal Stromal Cells but Maintains Immunomodulatory and Paracrine Activities Important for Renal Repair

Mesenchymal stem/stromal cells (MSCs) facilitate repair in experimental diabetic kidney disease (DKD). However, the hyperglycemic and uremic milieu may diminish regenerative capacity of patient-derived therapy. We hypothesized that DKD reduces human MSC paracrine function. Adipose-derived MSC from 38 participants with DKD and 16 control subjects were assessed for cell surface markers, trilineage differentiation, RNA sequencing (RNA-seq), in vitro function (coculture or conditioned medium experiments with T cells and human kidney cells [HK-2]), secretome profile, and cellular senescence abundance. The direction of association between MSC function and patient characteristics were also tested. RNA-seq analysis identified 353 differentially expressed genes and downregulation of several immunomodulatory genes/pathways in DKD-MSC versus Control-MSC. DKD-MSC phenotype, differentiation, and tube formation capacity were preserved, but migration was reduced. DKD-MSC with and without interferon-γ priming inhibited T-cell proliferation greater than Control-MSC. DKD-MSC medium contained higher levels of anti-inflammatory cytokines (indoleamine 2,3-deoxygenase 1 and prostaglandin-E2) and prorepair factors (hepatocyte growth factor and stromal cell-derived factor 1) but lower IL-6 versus control-MSC medium. DKD-MSC medium protected high glucose plus transforming growth factor-β-exposed HK-2 cells by reducing apoptotic, fibrotic, and inflammatory marker expression. Few DKD-MSC functions were affected by patient characteristics, including age, sex, BMI, hemoglobin A_1c, kidney function, and urine albumin excretion. However, senescence-associated β-galactosidase activity was lower in DKD-MSC from participants on metformin therapy. Therefore, while DKD altered the transcriptome and migratory function of culture-expanded MSCs, DKD-MSC functionality, trophic factor secretion, and immunomodulatory activities contributing to repair remained intact. These observations support testing of patient-derived MSC therapy and may inform preconditioning regimens in DKD clinical trials.

Serum neurofilament light protein correlates with unfavorable clinical outcomes in hospitalized patients with COVID-19

SARS-CoV-2 infection, the cause of coronavirus disease 2019 (COVID-19), causes neurological manifestations in a substantial proportion of patients. Determining the extent of neuronal injury is essential to better understand disease pathophysiology and to evaluate potential therapies. Prudencio et al. analyzed serum from 142 patients hospitalized with COVID-19 and showed that the expression of the neurofilament light protein (NFL), a marker of neuroaxonal injury, was elevated compared to healthy controls. In addition, serum NFL expression correlated with disease severity and tended to be reduced in subjects treated with remdesivir. The results suggest that serum NFL analysis should be incorporated when evaluating therapeutic trials for COVID-19.

Brain imaging studies of patients with COVID-19 show evidence of macro- and microhemorrhagic lesions, multifocal white matter hyperintensities, and lesions consistent with posterior reversible leukoencephalopathy. Imaging studies, however, are subject to selection bias, and prospective studies are challenging to scale. Here, we evaluated whether serum neurofilament light chain (NFL), a neuroaxonal injury marker, could predict the extent of neuronal damage in a cohort of 142 hospitalized patients with COVID-19. NFL was elevated in the serum of patients with COVID-19 compared to healthy controls, including those without overt neurological manifestations. Higher NFL serum concentrations were associated with worse clinical outcomes. In 100 hospitalized patients with COVID-19 treated with remdesivir, a trend toward lower NFL serum concentrations was observed. These data suggest that patients with COVID-19 may experience neuroaxonal injury and may be at risk for long-term neurological sequelae. Neuroaxonal injury should be considered as an outcome in acute pharmacotherapeutic trials for COVID-19.

A systematic review and meta-analysis of cell-based interventions in experimental diabetic kidney disease

Regenerative, cell‐based therapy is a promising treatment option for diabetic kidney disease (DKD), which has no cure. To prepare for clinical translation, this systematic review and meta‐analysis summarized the effect of cell‐based interventions in DKD animal models and treatment‐related factors modifying outcomes. Electronic databases were searched for original investigations applying cell‐based therapy in diabetic animals with kidney endpoints (January 1998‐May 2019). Weighted or standardized mean differences were estimated for kidney outcomes and pooled using random‐effects models. Subgroup analyses tested treatment‐related factor effects for outcomes (creatinine, urea, urine protein, fibrosis, and inflammation). In 40 studies (992 diabetic rodents), therapy included mesenchymal stem/stromal cells (MSC; 61%), umbilical cord/amniotic fluid cells (UC/AF; 15%), non‐MSC (15%), and cell‐derived products (13%). Tissue sources included bone marrow (BM; 65%), UC/AF (15%), adipose (9%), and others (11%). Cell‐based therapy significantly improved kidney function while reducing injury markers (proteinuria, histology, fibrosis, inflammation, apoptosis, epithelial‐mesenchymal‐transition, oxidative stress). Preconditioning, xenotransplantation, and disease‐source approaches were effective. MSC and UC/AF cells had greater effect on kidney function while cell products improved fibrosis. BM and UC/AF tissue sources more effectively improved kidney function and proteinuria vs adipose or other tissues. Cell dose, frequency, and administration route also imparted different benefits. In conclusion, cell‐based interventions in diabetic animals improved kidney function and reduced injury with treatment‐related factors modifying these effects. These findings may aid in development of optimal repair strategies through selective use of cells/products, tissue sources, and dose administrations to allow for successful adaptation of this novel therapeutic in human DKD.

Hypoxic preconditioning induces epigenetic changes and modifies swine mesenchymal stem cell angiogenesis and senescence in experimental atherosclerotic renal artery stenosis

Background

Atherosclerotic renal artery stenosis (ARAS) is a risk factor for ischemic and hypertensive kidney disease (HKD) for which autologous mesenchymal stem cell (MSC) appears to be a promising therapy. However, MSCs from ARAS patients exhibit impaired function, senescence, and DNA damage, possibly due to epigenetic mechanisms. Hypoxia preconditioning (HPC) exerts beneficial effects on cellular proliferation, differentiation, and gene and protein expression. We hypothesized that HPC could influence MSC function and senescence in ARAS by epigenetic mechanisms and modulating gene expression of chromatin-modifying enzymes.

Methods

Adipose-derived MSC harvested from healthy control (N = 8) and ARAS (N = 8) pigs were cultured under normoxia (20%O₂) or hypoxia (1%O₂) conditions. MSC function was assessed by migration, proliferation, and cytokine release in conditioned media. MSC senescence was evaluated by SA-β-gal activity. Specific pro-angiogenic and senescence genes were assessed by reverse transcription polymerase chain reaction (RT-PCR). Dot blotting was used to measure global genome 5-hydroxymethylcytosine (5hmC) levels on DNA and Western blotting of modified histone 3 (H3) proteins to quantify tri-methylated lysine-4 (H3K4me3), lysine-9 (H3K9me3), and lysine-27 (H3K27me3) residues.

Results

Specific pro-angiogenic genes in ARAS assessed by RT-PCR were lower at baseline but increased under HPC, while pro-senescence genes were higher in ARAS at baseline as compared healthy MSCs. ARAS MSCs under basal conditions, displayed higher H3K4me3, H3K27me3, and 5hmC levels compared to healthy MSCs. During HPC, global 5hmC levels were decreased while no appreciable changes occurred in histone H3 tri-methylation. ARAS MSCs cultured under HPC had higher migratory and proliferative capacity as well as increased vascular endothelial growth factor and epidermal growth factor expression compared to normoxia, and SA-β-gal activity decreased in both animal groups.

Conclusions

These data demonstrate that swine ARAS MSCs have decreased angiogenesis and increased senescence compared to healthy MSCs and that HPC mitigates MSC dysfunction, senescence, and DNA hydroxymethylation in ARAS MSC. Thus, HPC for MSCs may be considered for their optimization to improve autologous cell therapy in patients with nephropathies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02310-z.

Progress toward the Clinical Application of Mesenchymal Stromal Cells and Other Disease-Modulating Regenerative Therapies: Examples from the Field of Nephrology

Drawing from basic knowledge of stem-cell biology, embryonic development, wound healing, and aging, regenerative medicine seeks to develop therapeutic strategies that complement or replace conventional treatments by actively repairing diseased tissue or generating new organs and tissues. Among the various clinical-translational strategies within the field of regenerative medicine, several can be broadly described as promoting disease resolution indirectly through local or systemic interactions with a patient's cells, without permanently integrating or directly forming new primary tissue. In this review, we focus on such therapies, which we term disease-modulating regenerative therapies (DMRT), and on the extent to which they have been translated into the clinical arena in four distinct areas of nephrology: renovascular disease (RVD), sepsis-associated AKI (SA-AKI), diabetic kidney disease (DKD), and kidney transplantation (KTx). As we describe, the DMRT that has most consistently progressed to human clinical trials for these indications is mesenchymal stem/stromal cells (MSCs), which potently modulate ischemic, inflammatory, profibrotic, and immune-mediated tissue injury through diverse paracrine mechanisms. In KTx, several early-phase clinical trials have also tested the potential for ex vivo-expanded regulatory immune cell therapies to promote donor-specific tolerance and prevent or resolve allograft injury. Other promising DMRT, including adult stem/progenitor cells, stem cell-derived extracellular vesicles, and implantable hydrogels/biomaterials remain at varying preclinical stages of translation for these renal conditions. To date (2021), no DMRT has gained market approval for use in patients with RVD, SA-AKI, DKD, or KTx, and clinical trials demonstrating definitive, cost-effective patient benefits are needed. Nonetheless, exciting progress in understanding the disease-specific mechanisms of action of MSCs and other DMRT, coupled with increasing knowledge of the pathophysiologic basis for renal-tissue injury and the experience gained from pioneering early-phase clinical trials provide optimism that influential, regenerative treatments for diverse kidney diseases will emerge in the years ahead.

Validation of prognostic indices for short term mortality in an incident dialysis population of older adults >75

Rational and objective

Prognosis provides critical knowledge for shared decision making between patients and clinicians. While several prognostic indices for mortality in dialysis patients have been developed, their performance among elderly patients initiating dialysis is unknown, despite great need for reliable prognostication in that context. To assess the performance of 6 previously validated prognostic indices to predict 3 and/or 6 months mortality in a cohort of elderly incident dialysis patients.

Study design

Validation study of prognostic indices using retrospective cohort data. Indices were compared using the concordance (“c”)-statistic, i.e. area under the receiver operating characteristic curve (ROC). Calibration, sensitivity, specificity, positive and negative predictive values were also calculated.

Setting & participants

Incident elderly (age ≥75 years; n = 349) dialysis patients at a tertiary referral center.

Established predictors

Variables for six validated prognostic indices for short term (3 and 6 month) mortality prediction (Foley, NCI, REIN, updated REIN, Thamer, and Wick) were extracted from the electronic medical record. The indices were individually applied as per each index specifications to predict 3- and/or 6-month mortality.

Results

In our cohort of 349 patients, mean age was 81.5±4.4 years, 66% were male, and median survival was 351 days. The c-statistic for the risk prediction indices ranged from 0.57 to 0.73. Wick ROC 0.73 (0.68, 0.78) and Foley 0.67 (0.61, 0.73) indices performed best. The Foley index was weakly calibrated with poor overall model fit (p <0.01) and overestimated mortality risk, while the Wick index was relatively well-calibrated but underestimated mortality risk.

Limitations

Small sample size, use of secondary data, need for imputation, homogeneous population.

Conclusion

Most predictive indices for mortality performed moderately in our incident dialysis population. The Wick and Foley indices were the best performing, but had issues with under and over calibration. More accurate indices for predicting survival in older patients with kidney failure are needed.

Abstract MP01: Vasopressin Contributes To Differences In The Physiology Of Hypertension Between Non-Hispanic Blacks And Whites

Objective: Vasopressin increases water permeability and activity of the epithelial sodium channel ENaC in the distal nephron of the kidney, favoring increased water and sodium retention. We hypothesized that genetically mediated differences in circulating vasopressin concentrations could contribute to features of hypertension that vary between non-Hispanic blacks and whites. To test this hypothesis we measured copeptin, a fragment of pre-pro arginine vasopressin with a prolonged half-life that is more easily quantified.

Methods: The Genetic Epidemiology of Responses to Antihypertensives (GERA) I study was designed to identify predictors of response to diuretic therapy in non-Hispanic black and non-Hispanic white adults with essential hypertension. Blood samples were obtained after a 4 week washout of anti-hypertensive medication while on a sodium intake of 2 mmol/kg. Copeptin was measured from thawed EDTA plasma samples using the copeptin proAVP homogeneous automated immunofluorescent assay on the BRAHMS Kryptor Compact PLUS (Thermo Fisher).

Results: Copeptin was significantly higher in blacks (median: 7.4 pmol/L, IQR: 4.4-10.2 pmol/L) than in whites (median: 5.4 pmol/L, IQR: 3.6-8.0 pmol/L) (p <0.001), while renin was lower (Table 1). Racial differences remained significant (p = 0.001) in multivariate models that included 24 hour urine sodium excretion and calculated plasma osmolality.

Conclusions: Higher copeptin (vasopressin) concentrations in non-Hispanic blacks compared to whites may contribute to the distinct differences in the hypertensive phenotypes between these racial groups. The underlying mechanism(s) require further study.

Protocolized exercise improves frailty parameters and lower extremity impairment: A promising prehabilitation strategy for kidney transplant candidates

BACKGROUND

Frailty and decreased functional status are risk factors for adverse kidney transplant (KT) outcomes. Our objective was to examine the efficacy of an exercise intervention on frailty and decreased functional status in a cohort of patients with advanced chronic kidney disease (CKD).

METHODS

We conducted a prospective study involving 21 adults with ≥stage 4 CKD who were (a) frail or pre-frail by Fried phenotype and/or (b) had lower extremity impairment [short physical performance battery score ≤10]. The intervention consisted of two supervised outpatient exercise sessions per week for 8 weeks.

RESULTS

Among our cohort, median participant age was 62 years (interquartile range, 53-67) and 85.7% had been evaluated for KT. Following the study, participants reported satisfaction with the intervention and multiple frailty parameters improved significantly, including fatigue, physical activity, walking time, and grip strength. Lower extremity impairment also improved (90.5%-61.9%, P = .03). No study-related adverse events occurred.

CONCLUSIONS

Preliminary data from this study suggest that a supervised, outpatient exercise intervention is safe, acceptable, feasible, and associated with improved frailty parameters, and lower extremity function, in patients with advanced CKD. Further studies are needed to confirm these findings and determine whether this prehabilitation strategy improves KT outcomes.

Metabolic Syndrome Modulates Protein Import into the Mitochondria of Porcine Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are currently being tested in several clinical trials. Mitochondria regulate many aspects of MSC function. Mitochondrial preproteins are rapidly translated and trafficked into the mitochondrion for assembly in their final destination, but whether coexisting cardiovascular risk factors modulate this process is unknown. We hypothesized that metabolic syndrome (MetS) modulates mitochondrial protein import in porcine MSCs. MSCs were isolated from porcine abdominal adipose tissue after 16 weeks of Lean or MetS diet (n = 5 each). RNA-sequencing was performed and differentially expressed mitochondrial mRNAs and microRNAs were identified and validated. Protein expression of transporters of mitochondrial proteins (presequences and precursors) and their respective substrates were measured. Mitochondrial homeostasis was assessed by Western blot and function by cytochrome-c oxidase-IV activity. Forty-five mitochondrial mRNAs were upregulated and 25 downregulated in MetS-MSCs compared to Lean-MSCs. mRNAs upregulated in MetS-MSCs encoded for precursor proteins, whereas those downregulated encoded for presequences. Micro-RNAs upregulated in MetS-MSCs primarily target mRNAs encoding for presequences. Transporters of precursor proteins and their substrates were also upregulated, associated with changes in mitochondrial homeostasis and dysfunction. MetS interferes with mitochondrial protein import, favoring upregulation of precursor proteins, which might be linked to post-transcriptional regulation of presequences. This in turn alters mitochondrial homeostasis and impairs energy production. Our observations highlight the importance of mitochondria in MSC function and provide a molecular framework for optimization of cell-based strategies as we move towards their clinical application.

Increased cellular senescence in the murine and human stenotic kidney: Effect of mesenchymal stem cells

Cell stress may give rise to insuperable growth arrest, which is defined as cellular senescence. Stenotic kidney (STK) ischemia and injury induced by renal artery stenosis (RAS) may be associated with cellular senescence. Mesenchymal stem cells (MSCs) decrease some forms of STK injury, but their ability to reverse senescence in RAS remains unknown. We hypothesized that RAS evokes STK senescence, which would be ameliorated by MSCs. Mice were studied after 4 weeks of RAS, RAS treated with adipose tissue-derived MSCs 2 weeks earlier, or sham. STK senescence-associated β-galactosidase (SA-β-Gal) activity was measured. Protein and gene expression was used to assess senescence and the senescence-associated secretory phenotype (SASP), and staining for renal fibrosis, inflammation, and capillary density. In addition, senescence was assessed as p16+ and p21+ urinary exosomes in patients with renovascular hypertension (RVH) without or 3 months after autologous adipose tissue-derived MSC delivery, and in healthy volunteers (HV). In RAS mice, STK SA-β-Gal activity increased, and senescence and SASP marker expression was markedly elevated. MSCs improved renal function, fibrosis, inflammation, and capillary density, and attenuated SA-β-Gal activity, but most senescence and SASP levels remained unchanged. Congruently, in human RVH, p21+ urinary exosomes were elevated compared to HV, and only slightly improved by MSC, whereas p16+ exosomes remained unchanged. Therefore, RAS triggers renal senescence in both mice and human subjects. MSCs decrease renal injury, but only partly mitigate renal senescence. These observations support exploration of targeted senolytic therapy in RAS.

Use of Potentially Nephrotoxic Medications by U.S. Adults with Chronic Kidney Disease: NHANES, 2011-2016

BACKGROUND

People with chronic kidney disease (CKD) are at risk for adverse events and/or CKD progression with use of renally eliminated or nephrotoxic medications.

OBJECTIVE

To examine the prevalence of potentially inappropriate medication (PIM) use by U.S. adults by CKD stage and self-reported CKD awareness.

DESIGN

Cross-sectional analysis of National Health and Nutrition Examination Surveys, 2011-2016 PARTICIPANTS: Non-pregnant adults with stages 3a (eGFR 45-59 mL/min/1.73 m2), 3b (eGFR 30-44), or 4-5 (eGFR < 30) CKD, stratified as CKD-aware/unaware.

MAIN MEASURES

PIMs were identified on the basis of KDIGO guidelines, label information, and literature review. We calculated proportions using any and individual PIMs, assessing for differences over CKD awareness within each CKD stage. Analyses were adjusted for age, sex, race/ethnicity, education, comorbidities, and insurance type.

KEY RESULTS

Adjusted proportions of U.S. adults taking any PIM(s) exceeded 50% for all CKD stages and awareness categories, and were highest among CKD-unaware patients with stages 4-5 CKD: 66.6% (95% CI, 55.5-77.8). Proton pump inhibitors, opioids, metformin, sulfonylureas, and non-steroidal anti-inflammatory drugs (NSAIDs) were all used frequently across CKD stages. NSAIDs were used less frequently when CKD-aware by patients with stage 3a CKD (2.2% [95% CI, - 0.3 to 4.7] vs. 10.7% [95% CI, 7.6 to 13.8]) and stages 4-5 CKD (0.8% [95% CI, - 0.9 to 2.5] vs. 16.5% [95% CI, 4.0 to 29.0]). Metformin was used less frequently when CKD-aware by patients with stage 3b CKD (8.1% [95% CI, 0.3-15.9] vs. 26.5% [95% CI, 17.4-35.7]) and stages 4-5 CKD (none vs. 20.8% [95% CI, 1.8-39.8]). The impact of CKD awareness was statistically significant after correction for multiple comparisons only for NSAIDs in stage 3a CKD.

CONCLUSIONS

PIMs are frequently used by people with CKD, with some impact of CKD awareness on NSAID and metformin use. This may lead to adverse outcomes or hasten CKD progression, reinforcing the need for improved medication management among people with CKD.

In a Phase 1a escalating clinical trial, autologous mesenchymal stem cell infusion for renovascular disease increases blood flow and the glomerular filtration rate while reducing inflammatory biomarkers and blood pressure

Atherosclerotic renovascular disease (ARVD) reduces tissue perfusion and eventually leads to loss of kidney function with limited therapeutic options. Here we describe results of Phase 1a escalating dose clinical trial of autologous mesenchymal stem cell infusion for ARVD. Thirty-nine patients with ARVD were studied on two occasions separated by three months. Autologous adipose-derived mesenchymal stem cells were infused through the renal artery in 21 patients at three different dose levels (1, 2.5 and 5.0 × 105 cells/kg) in seven patients each. We measured renal blood flow, glomerular filtration rate (GFR) (iothalamate and estimated GFR), renal vein cytokine levels, blood pressure, and tissue oxygenation before and three months after stem cell delivery. These indices were compared to those of 18 patients with ARVD matched for age, kidney function and blood pressure receiving medical therapy alone that underwent an identical study protocol. Cultured mesenchymal stem cells were also studied in vitro. For the entire stem cell treated-cohort, mean renal blood flow in the treated stenotic kidney significantly increased after stem cell infusion from (164 to 190 ml/min). Hypoxia, renal vein inflammatory cytokines, and angiogenic biomarkers significantly decreased following stem cell infusion. Mean systolic blood pressure significantly fell (144 to 136 mmHg) and the mean two-kidney GFR (Iothalamate) modestly but significantly increased from (53 to 56 ml/min). Changes in GFR and blood pressure were largest in the high dose stem cell treated individuals. No such changes were observed in the cohort receiving medical treatment alone. Thus, our data demonstrate the potential for autologous mesenchymal stem cell to increase blood flow, GFR and attenuate inflammatory injury in post-stenotic kidneys. The observation that some effects are dose-dependent and related to in-vitro properties of mesenchymal stem cell may direct efforts to maximize potential therapeutic efficacy.

Transplanted senescent renal scattered tubular-like cells induce injury in the mouse kidney

Cellular senescence, a permanent arrest of cell proliferation, is characterized by a senescence-associated secretory phenotype (SASP), which reinforces senescence and exerts noxious effects on adjacent cells. Recent studies have suggested that transplanting small numbers of senescent cells suffices to provoke tissue inflammation. We hypothesized that senescent cells can directly augment renal injury. Primary scattered tubular-like cells (STCs) acquired from pig kidneys were irradiated by 10 Gy of cesium radiation, and 3 wk later cells were characterized for levels of senescence and SASP markers. Control or senescent STCs were then prelabeled and injected (5 × 10⁵ cells) into the aorta of C57BL/6J mice. Four weeks later, renal oxygenation was studied in vivo using 16.4-T magnetic resonance imaging and function by plasma creatinine level. Renal markers of SASP, fibrosis, and microvascular density were evaluated ex vivo. Per flow cytometry, irradiation induced senescence in 80-99% of STCs, which showed increased gene expression of senescence and SASP markers, senescence-associated β-galactosidase staining, and cytokine levels (especially IL-6) secreted in conditioned medium. Four weeks after injection, cells were detected engrafted in the mouse kidneys with no evidence for rejection. Plasma creatinine and renal tissue hypoxia increased in senescent compared with control cells. Senescent kidneys were more fibrotic, with fewer CD31⁺ endothelial cells, and showed upregulation of IL-6 gene expression. Therefore, exogenously delivered senescent renal STCs directly injure healthy mouse kidneys. Additional studies are needed to determine the role of endogenous cellular senescence in the pathogenesis of kidney injury and evaluate the utility of senolytic therapy.

Human Obesity Induces Dysfunction and Early Senescence in Adipose Tissue-Derived Mesenchymal Stromal/Stem Cells

BACKGROUND

Chronic inflammatory conditions like obesity may adversely impact the biological functions underlying the regenerative potential of mesenchymal stromal/stem cells (MSC). Obesity can impair MSC function by inducing cellular senescence, a growth-arrest program that transitions cells to a pro-inflammatory state. However, the effect of obesity on adipose tissue-derived MSC in human subjects remains unclear. We tested the hypothesis that obesity induces senescence and dysfunction in human MSC.

METHODS

MSC were harvested from abdominal subcutaneous fat collected from obese and age-matched non-obese subjects (n = 40) during bariatric or kidney donation surgeries, respectively. MSC were characterized, their migration and proliferation assessed, and cellular senescence evaluated by gene expression of cell-cycle arrest and senescence-associated secretory phenotype markers. In vitro studies tested MSC effect on injured human umbilical vein endothelial cells (HUVEC) function.

RESULTS

Mean age was 59 ± 8 years, 66% were females. Obese subjects had higher body-mass index (BMI) than non-obese. MSC from obese subjects exhibited lower proliferative capacities than non-obese-MSC, suggesting decreased function, whereas their migration remained unchanged. Senescent cell burden and phenotype, manifested as p16, p53, IL-6, and MCP-1 gene expression, were significantly upregulated in obese subjects' MSC. BMI correlated directly with expression of p16, p21, and IL-6. Furthermore, co-incubation with non-obese, but not with obese-MSC, restored VEGF expression and tube formation that were blunted in injured HUVEC.

CONCLUSION

Human obesity triggers an early senescence program in adipose tissue-derived MSC. Thus, obesity-induced cellular injury may alter efficacy of this endogenous repair system and hamper the feasibility of autologous transplantation in obese individuals.

Increased renal cellular senescence in murine high-fat diet: effect of the senolytic drug quercetin

Obesity and dyslipidemia can be associated with cellular senescence, and may impair kidney function. However, whether senescence contributes to renal dysfunction in these conditions remains unclear. Quercetin is an abundant dietary flavonoid that selectively clears inhibiting PI3K/AKT and p53/p21/serpines and inducing apoptosis. We hypothesized that high-fat-diet-induced obesity causes renal senescence, which would be mitigated by quercetin. C57BL/6J mice fed either standard chow or high-fat diets (HFDs) were treated with quercetin (50 mg/kg) or vehicle 5-days biweekly via oral gavage for 10 weeks. Subsequently, renal function was studied in vivo using magnetic resonance imaging, and renal senescence and histology were evaluated ex vivo. Mice fed with a HFD developed obesity and hypercholesterolemia, whereas renal size remained unchanged. Murine obesity impaired renal function and cortical oxygenation, and induced glomerulomegaly. Renal markers of senescence (eg, expression of p16, p19, and p53) and its secretory phenotype were upregulated in the obese hypercholesterolemic compared to lean mice in renal tubular cells, but attenuated in quercetin-treated murine kidneys, as was renal fibrosis. Quercetin treatment also increased renal cortical oxygenation and decreased plasma creatinine levels in obese mice, whereas body weight and cholesterol levels were unaltered. Therefore, murine obesity and dyslipidemia induce renal tissue senescence and impairs kidney function, which is alleviated by chronic senolytic treatment. These findings implicate senescence in loss of kidney function in murine dyslipidemia and obesity, and support further studies of senolytic therapy in obesity.

Survival outcomes for patients with surgically induced end-stage renal disease

INTRODUCTION

While medically induced end-stage renal disease (m-ESRD) has been well-studied, outcomes in patients with surgically induced ESRD (s-ESRD) are unknown. We sought to quantitatively compare the non-oncological outcomes for s-ESRD and m-ESRD in a large, population-based cohort.

METHODS

Medicare patients >65 years old initiating hemodialysis were identified using the U.S. Renal Data System database (2000-2012). Metastatic cancer, prior transplant history, and nephrectomy for polycystic kidney disease were exclusion criteria. Patients were classified as having s-ESRD or m-ESRD based on hospital and physician claims for nephrectomy within a year preceding the onset of maintenance hemodialysis. Outcomes included non-cancer mortality (NCM), overall survival (OS), cardiovascular event (CVE), and renal transplantation. Time-to-event analyses were performed using Kaplan-Meier and cumulative incidence curves, and multivariable Cox and Fine-and-Grey regression models.

RESULTS

The cohort included 312 612 patients, of whom 1648 (0.53%) had s-ESRD. Compared to m-ESRD patients, s-ESRD patients had a significantly lower five-year cumulative incidence of NCM (68% vs. 80%; p<0.001) and CVE (62% vs. 68%; p<0.001), with a correspondingly higher probability of OS (22% vs. 17%; p<0.001) and rate of renal transplantation (3.6% vs. 2.0%; p<0.001). On multivariable analyses, s-ESRD remained associated with lower risks of NCM (p<0.001) and CVE (p<0.001), improved OS (p<0.001), and higher chance of renal transplantation (p<0.001).

CONCLUSIONS

While outcomes for s-ESRD appear more favorable than m-ESRD, s-ESRD is still associated with a substantial risk of NCM and CVE, and a low incidence of renal transplantation in Medicare patients >65 years old. These non-oncological outcomes are worth considering in patients potentially facing postoperative ESRD.

Senolytics decrease senescent cells in humans: Preliminary report from a clinical trial of Dasatinib plus Quercetin in individuals with diabetic kidney disease

Background

Senescent cells, which can release factors that cause inflammation and dysfunction, the senescence-associated secretory phenotype (SASP), accumulate with ageing and at etiological sites in multiple chronic diseases. Senolytics, including the combination of Dasatinib and Quercetin (D + Q), selectively eliminate senescent cells by transiently disabling pro-survival networks that defend them against their own apoptotic environment. In the first clinical trial of senolytics, D + Q improved physical function in patients with idiopathic pulmonary fibrosis (IPF), a fatal senescence-associated disease, but to date, no peer-reviewed study has directly demonstrated that senolytics decrease senescent cells in humans.

Methods

In an open label Phase 1 pilot study, we administered 3 days of oral D 100 mg and Q 1000 mg to subjects with diabetic kidney disease (N = 9; 68·7 ± 3·1 years old; 2 female; BMI:33·9 ± 2·3 kg/m²; eGFR:27·0 ± 2·1 mL/min/1·73m²). Adipose tissue, skin biopsies, and blood were collected before and 11 days after completing senolytic treatment. Senescent cell and macrophage/Langerhans cell markers and circulating SASP factors were assayed.

Findings

D + Q reduced adipose tissue senescent cell burden within 11 days, with decreases in p16^INK4A-and p21^CIP1-expressing cells, cells with senescence-associated β-galactosidase activity, and adipocyte progenitors with limited replicative potential. Adipose tissue macrophages, which are attracted, anchored, and activated by senescent cells, and crown-like structures were decreased. Skin epidermal p16^INK4A+ and p21^CIP1+ cells were reduced, as were circulating SASP factors, including IL-1α, IL-6, and MMPs-9 and −12.

Interpretation

“Hit-and-run” treatment with senolytics, which in the case of D + Q have elimination half-lives <11 h, significantly decreases senescent cell burden in humans.

Fund

NIH and Foundations.

ClinicalTrials.gov Identifier: NCT02848131. Senescence, Frailty, and Mesenchymal Stem Cell Functionality in Chronic Kidney Disease: Effect of Senolytic Agents.

Prediction of Risk of Death for Patients Starting Dialysis: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Dialysis is a preference-sensitive decision where prognosis may play an important role. Although patients desire risk prediction, nephrologists are wary of sharing this information. We reviewed the performance of prognostic indices for patients starting dialysis to facilitate bedside translation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Systematic review and meta-analysis following the PRISMA guidelines. We searched Ovid MEDLINE, Ovid Embase, Ovid Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and Scopus for eligible studies of patients starting dialysis published from inception to December 31, 2018.

SELECTION CRITERIA

Articles describing validated prognostic indices predicting mortality at the start of dialysis. We excluded studies limited to prevalent dialysis patients, AKI and studies excluding mortality in the first 1-3 months. Two reviewers independently screened abstracts, performed full text assessment of inclusion criteria and extracted: study design, setting, population demographics, index performance and risk of bias. Pre-planned random effects meta-analysis was performed stratified by index and predictive window to reduce heterogeneity.

RESULTS

Of 12,132 articles screened and 214 reviewed in full text, 36 studies were included describing 32 prognostic indices. Predictive windows ranged from 3 months to 10 years, cohort sizes from 46 to 52,796. Meta-analysis showed discrimination area under the curve (AUC) of 0.71 (95% confidence interval, 0.69 to 073) with high heterogeneity (I2=99.12). Meta-analysis by index showed highest AUC for The Obi, Ivory, and Charlson comorbidity index (CCI)=0.74, also CCI was the most commonly used (ten studies). Other commonly used indices were Kahn-Wright index (eight studies, AUC 0.68), Hemmelgarn modification of the CCI (six studies, AUC 0.66) and REIN index (five studies, AUC 0.69). Of the indices, ten have been validated externally, 16 internally and nine were pre-existing validated indices. Limitations include heterogeneity and exclusion of large cohort studies in prevalent patients.

CONCLUSIONS

Several well validated indices with good discrimination are available for predicting survival at dialysis start.

Metabolic Syndrome Induces Release of Smaller Extracellular Vesicles from Porcine Mesenchymal Stem Cells

Mesenchymal stromal/stem cells (MSCs) belong to the endogenous cellular reparative system, and can be used exogenously in cell-based therapy. MSCs release extracellular vesicles (EVs), including exosomes and microvesicles, which mediate some of their therapeutic activity through intercellular communication. We have previously demonstrated that metabolic syndrome (MetS) modifies the cargo packed within swine EV, but whether it influences their phenotypical characteristics remains unclear. This study tested the hypothesis that MetS shifts the size distribution of MSC-derived EVs. Adipose tissue-derived MSC-EV subpopulations from Lean (n = 6) and MetS (n = 6) pigs were characterized for number and size using nanoparticle-tracking analysis, flow cytometry, and transmission electron microscopy. Expression of exosomal genes was determined using next-generation RNA-sequencing (RNA-seq). The number of EV released from Lean and MetS pig MSCs was similar, yet MetS-MSCs yielded a higher proportion of small-size EVs (202.4 ± 17.7 nm vs. 280.3 ± 15.1 nm), consistent with exosomes. RNA-seq showed that their EVs were enriched with exosomal markers. Lysosomal activity remained unaltered in MetS-MSCs. Therefore, MetS alters the size distribution of MSC-derived EVs in favor of exosome release. These observations may reflect MSC injury and membrane recycling in MetS or increased expulsion of waste products, and may have important implications for development of adequate cell-based treatments.

Cannabis abuse and dependence in kidney transplant candidates

OBJECTIVE

Cannabis is the most commonly used non-alcohol intoxicant in the general population. There are no consistent guidelines on the implications of cannabis abuse and dependence (CAD) in kidney transplant candidates. The aims of this study were to characterize kidney transplant candidates with comorbid CAD and examine the implications of CAD on transplant candidacy.

METHOD

This was a retrospective cohort study of kidney transplant candidates meeting diagnostic criteria for CAD at a tertiary center from 2012 to 2016. Candidates were reviewed for psychiatric and substance use disorders (SUDs), family history, and medical variables. The cohort was divided by severity of CAD and transplant listing status for comparisons. Statistical analysis included Kruskal-Wallis tests for continuous variables and Fisher's Exact Test for categorical variables.

RESULTS

Sixty-one of 2067 (3%) kidney transplant candidates met criteria for CAD, and 13/61 (21%) underwent transplantation. Of 61, 58% smoked cannabis daily, 47% had alcohol dependence history, 31% had other illicit drug dependencies, 38% were smokers, 60% had a SUD family history, and 42% and 27% had depressive and anxiety disorders, respectively. Severity of CAD was inversely associated with transplant listing; those with cannabis abuse were more often listed than those with dependence (67% vs 33%, p = .02) by study end. Three case presentations illustrate cannabis-related issues.

CONCLUSION

In this cohort, kidney transplant candidates with comorbid CAD have high prevalence of other substance use disorders, psychiatric comorbidities, and strong family histories of addictions that resemble other SUD populations. These findings have implications for pre-transplant screening and treatment and post-transplant monitoring.

Targeting senescent cells alleviates obesity-induced metabolic dysfunction

Adipose tissue inflammation and dysfunction are associated with obesity-related insulin resistance and diabetes, but mechanisms underlying this relationship are unclear. Although senescent cells accumulate in adipose tissue of obese humans and rodents, a direct pathogenic role for these cells in the development of diabetes remains to be demonstrated. Here, we show that reducing senescent cell burden in obese mice, either by activating drug-inducible "suicide" genes driven by the p16Ink4a promoter or by treatment with senolytic agents, alleviates metabolic and adipose tissue dysfunction. These senolytic interventions improved glucose tolerance, enhanced insulin sensitivity, lowered circulating inflammatory mediators, and promoted adipogenesis in obese mice. Elimination of senescent cells also prevented the migration of transplanted monocytes into intra-abdominal adipose tissue and reduced the number of macrophages in this tissue. In addition, microalbuminuria, renal podocyte function, and cardiac diastolic function improved with senolytic therapy. Our results implicate cellular senescence as a causal factor in obesity-related inflammation and metabolic derangements and show that emerging senolytic agents hold promise for treating obesity-related metabolic dysfunction and its complications.

Care Transitions Program for High-Risk Frail Older Adults is Most Beneficial for Patients with Cognitive Impairment

BACKGROUND

Although posthospitalization care transitions programs (CTP) are highly diverse, their overall program thoroughness is most predictive of their success.

OBJECTIVE

To identify components of a successful homebased CTP and patient characteristics that are most predictive of reduced 30-day readmissions.

DESIGN

Retrospective cohort.

PATIENTS

A total of 315 community-dwelling, hospitalized, older adults (≥60 years) at high risk for readmission (Elder Risk Assessment score ≥16), discharged home over the period of January 1, 2011 to June 30, 2013.

SETTING

Midwest primary care practice in an integrated health system.

INTERVENTION

Enrollment in a CTP during acute hospitalization.

MEASUREMENTS

The primary outcome was all-cause readmission within 30 days of the first CTP evaluation. Logistic regression was used to examine independent variables, including patient demographics, comorbidities, number of medications, completion, and timing of program fidelity measures, and prior utilization of healthcare.

RESULTS

The overall 30-day readmission rate was 17.1%. The intensity of follow-up varied among patients, with 17.1% and 50.8% of the patients requiring one and ≥3 home visits, respectively, within 30 days. More than half (54.6%) required visits beyond 30 days. Compared with patients who were not readmitted, readmitted patients were less likely to exhibit cognitive impairment (29.6% vs 46.0%; P = .03) and were more likely to have high medication use (59.3% vs 44.4%; P = .047), more emergency department (ED; 0.8 vs 0.4; P = .03) and primary care visits (4.0 vs 3.0; P = .018), and longer cumulative time in the hospital (4.6 vs 2.5 days; P = .03) within 180 days of the index hospitalization. Multivariable analysis indicated that only cognitive impairment and previous ED visits were important predictors of readmission.

CONCLUSIONS

No single CTP component reliably predicted reduced readmission risk. Patients with cognitive impairment and polypharmacy derived the most benefit from the program.

Tissue hypoxia, inflammation, and loss of glomerular filtration rate in human atherosclerotic renovascular disease

The relationships between renal blood flow (RBF), tissue oxygenation, and inflammatory injury in atherosclerotic renovascular disease (ARVD) are poorly understood. We sought to correlate RBF and tissue hypoxia with glomerular filtration rate (GFR) in 48 kidneys from patients with ARVD stratified by single kidney iothalamate GFR (sGFR). Oxygenation was assessed by blood oxygenation level dependent magnetic resonance imaging (BOLD MRI), which provides an index for the levels of deoxyhemoglobin within a defined volume of tissue (R2*). sGFR correlated with RBF and with the severity of vascular stenosis as estimated by duplex velocities. Higher cortical R2* and fractional hypoxia and higher levels of renal vein neutrophil-gelatinase-associated-lipocalin (NGAL) and monocyte-chemoattractant protein-1 (MCP-1) were observed at lower GFR, with an abrupt inflection below 20 ml/min. Renal vein MCP-1 levels correlated with cortical R2* and with fractional hypoxia. Correlations between cortical R2* and RBF in the highest sGFR stratum (mean sGFR 51 ± 12 ml/min; R = -0.8) were degraded in the lowest sGFR stratum (mean sGFR 8 ± 3 ml/min; R = -0.1). Changes in fractional hypoxia after furosemide were also absent in the lowest sGFR stratum. These data demonstrate relative stability of renal oxygenation with moderate reductions in RBF and GFR but identify a transition to overt hypoxia and inflammatory cytokine release with severely reduced GFR. Tissue oxygenation and RBF were less correlated in the setting of reduced sGFR, consistent with variable oxygen consumption or a shift to alternative mechanisms of tissue injury. Identifying transitions in tissue oxygenation may facilitate targeted therapy in ARVD.

Oxalosis Associated With High-Dose Vitamin C Ingestion in a Peritoneal Dialysis Patient

We report a case of systemic oxalosis involving the eyes and joints due to long-term use of high-dose vitamin C in a patient receiving maintenance peritoneal dialysis (PD). This 76-year-old woman with autosomal dominant polycystic kidney disease underwent living unrelated kidney transplantation 10 years earlier. The transplant failed 6 months before presentation, and she initiated hemodialysis therapy before transitioning to PD therapy 4 months later. During the month before presentation, the patient noted worsening arthralgias and decreased vision. Ophthalmologic examination revealed proliferative retinopathy and calcium oxalate crystals. Plasma oxalate level was markedly elevated at 187 (reference range, <1.7) μmol/L, and urine oxalate-creatinine ratio was high (0.18mg/mg). The patient reported taking up to 4g of vitamin C per day for several years. Workup for causes of primary and secondary hyperoxaluria was otherwise negative. Vitamin C use was discontinued, and the patient transitioned to daily hemodialysis for 2 weeks. Plasma oxalate level before the dialysis session decreased but remained higher (30-53μmol/L) than typical for dialysis patients. Upon discharge, the patient remained on thrice-weekly hemodialysis therapy with stabilized vision and improved joint symptoms. This case highlights the risk of high-dose vitamin C use in patients with advanced chronic kidney disease, especially when maintained on PD therapy.

Senescence marker activin A is increased in human diabetic kidney disease: association with kidney function and potential implications for therapy

OBJECTIVE

Activin A, an inflammatory mediator implicated in cellular senescence-induced adipose tissue dysfunction and profibrotic kidney injury, may become a new target for the treatment of diabetic kidney disease (DKD) and chronic kidney diseases. We tested the hypothesis that human DKD-related injury leads to upregulation of activin A in blood and urine and in a human kidney cell model. We further hypothesized that circulating activin A parallels kidney injury markers in DKD.

RESEARCH DESIGN AND METHODS

In two adult diabetes cohorts and controls (Minnesota, USA; Galway, Ireland), the relationships between plasma (or urine) activin A, estimated glomerular filtration rate (eGFR) and DKD injury biomarkers were tested with logistic regression and correlation coefficients. Activin A, inflammatory, epithelial-mesenchymal-transition (EMT) and senescence markers were assayed in human kidney (HK-2) cells incubated in high glucose plus transforming growth factor-β1 or albumin.

RESULTS

Plasma activin A levels were elevated in diabetes (n=206) compared with controls (n=76; 418.1 vs 259.3 pg/mL; p<0.001) and correlated inversely with eGFR (r_s=-0.61; p<0.001; diabetes). After eGFR adjustment, only albuminuria (OR 1.56, 95% CI 1.16 to 2.09) and tumor necrosis factor receptor-1 (OR 6.40, 95% CI 1.08 to 38.00) associated with the highest activin tertile. Albuminuria also related to urinary activin (r_s=0.65; p<0.001). Following in vitro HK-2 injury, activin, inflammatory, EMT genes and supernatant activin levels were increased.

CONCLUSIONS

Circulating activin A is increased in human DKD and correlates with reduced kidney function and kidney injury markers. DKD-injured human renal tubule cells develop a profibrotic and inflammatory phenotype with activin A upregulation. These findings underscore the role of inflammation and provide a basis for further exploration of activin A as a diagnostic marker and therapeutic target in DKD.

Micro-RNAS Regulate Metabolic Syndrome-induced Senescence in Porcine Adipose Tissue-derived Mesenchymal Stem Cells through the P16/MAPK Pathway

Mesenchymal stem cells (MSCs) constitute an important repair system, but may be impaired by exposure to cardiovascular risk factors. Consequently, adipose tissue-derived MSCs from pigs with the metabolic syndrome (MetS) show decreased vitality. A growing number of microRNAs (miRNAs) are recognized as key modulators of senescence, but their role in regulating senescence in MSC in MetS is unclear. We tested the hypothesis that MetS upregulates in MSC expression of miRNAs that can serve as post-transcriptional regulators of senescence-associated (SA) genes. MSCs were collected from swine abdominal adipose tissue after 16 weeks of Lean or Obese diet ( n = 6 each). Next-generation miRNA sequencing (miRNA-seq) was performed to identify miRNAs up-or down-regulated in MetS-MSCs compared with Lean-MSCs. Functional pathways of SA genes targeted by miRNAs were analyzed using gene ontology. MSC senescence was evaluated by p16 and p21 immunoreactivity, H2AX protein expression, and SA-β-Galactosidase activity. In addition, gene expression of p16, p21, MAPK3 (ERK1) and MAPK14, and MSC migration were studied after inhibition of SA-miR-27b. Senescence biomarkers were significantly elevated in MetS-MSCs. We found seven upregulated miRNAs, including miR-27b, and three downregulated miRNAs in MetS-MSCs, which regulate 35 SA genes, particularly MAPK signaling. Inhibition of miR-27b in cultured MSCs downregulated p16 and MARP3 genes, and increased MSC migration. MetS modulates MSC expression of SA-miRNAs that may regulate their senescence, and the p16 pathway seems to play an important role in MetS-induced MSC senescence.

Risk of ESRD and Mortality in Kidney and Bladder Stone Formers

RATIONALE & OBJECTIVES

Kidney stones have been associated with increased risk for end-stage renal disease (ESRD). However, it is unclear whether there is also an increased risk for mortality and if these risks are uniform across clinically distinct categories of stone formers.

STUDY DESIGN

Historical matched-cohort study.

SETTING & PARTICIPANTS

Stone formers in Olmsted County, MN, between 1984 and 2012 identified using International Classification of Diseases, Ninth Revision codes. Age- and sex-matched individuals who had no codes for stones were the comparison group.

PREDICTOR

Stone formers were placed into 5 mutually exclusive categories after review of medical charts: incident symptomatic kidney, recurrent symptomatic kidney, asymptomatic kidney, bladder only, and miscoded (no stone).

OUTCOMES

ESRD, mortality, cardiovascular mortality, and cancer mortality.

ANALYTICAL APPROACH

Cox proportional hazards models with adjustment for baseline comorbid conditions.

RESULTS

Overall, 65 of 6,984 (0.93%) stone formers and 102 of 28,044 (0.36%) non-stone formers developed ESRD over a mean follow-up of 12.0 years. After adjusting for baseline hypertension, diabetes mellitus, dyslipidemia, gout, obesity, and chronic kidney disease, risk for ESRD was higher in recurrent symptomatic kidney (HR, 2.34; 95% CI, 1.08-5.07), asymptomatic kidney (HR, 3.94; 95% CI, 1.65-9.43), and miscoded (HR, 6.18; 95% CI, 2.25-16.93) stone formers, but not in incident symptomatic kidney or bladder stone formers. The adjusted risk for all-cause mortality was higher in asymptomatic kidney (HR, 1.40; 95% CI, 1.18-1.67) and bladder (HR, 1.37; 95% CI, 1.12-1.69) stone formers. Chart review of asymptomatic and miscoded stone formers suggested increased risk for adverse outcomes related to diagnoses including urinary tract infection, cancer, and musculoskeletal or gastrointestinal pain.

CONCLUSIONS

The higher risk for ESRD in recurrent symptomatic compared with incident symptomatic kidney stone formers suggests that stone events are associated with kidney injury. The clinical indication for imaging in asymptomatic stone formers, the correct diagnosis in miscoded stone formers, and the cause of a bladder outlet obstruction in bladder stone formers may explain the higher risk for ESRD or death in these groups.

End of Life, Withdrawal, and Palliative Care Utilization among Patients Receiving Maintenance Hemodialysis Therapy

BACKGROUND AND OBJECTIVES

Withdrawal from maintenance hemodialysis before death has become more common because of high disease and treatment burden. The study objective was to identify patient factors and examine the terminal course associated with hemodialysis withdrawal, and assess patterns of palliative care involvement before death among patients on maintenance hemodialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We designed an observational cohort study of adult patients on incident hemodialysis in a midwestern United States tertiary center, from January 2001 to November 2013, with death events through to November 2015. Logistic regression models evaluated associations between patient characteristics and withdrawal status and palliative care service utilization.

RESULTS

Among 1226 patients, 536 died and 262 (49% of 536) withdrew. A random sample (10%; 52 out of 536) review of Death Notification Forms revealed 73% sensitivity for withdrawal. Risk factors for withdrawal before death included older age, white race, palliative care consultation within 6 months, hospitalization within 30 days, cerebrovascular disease, and no coronary artery disease. Most withdrawal decisions were made by patients (60%) or a family member (33%; surrogates). The majority withdrew either because of acute medical complications (51%) or failure to thrive/frailty (22%). After withdrawal, median time to death was 7 days (interquartile range, 4-11). In-hospital deaths were less common in the withdrawal group (34% versus 46% nonwithdrawal, P=0.003). A third (34%; 90 out of 262) of those that withdrew received palliative care services. Palliative care consultation in the withdrawal group was associated with longer hemodialysis duration (odds ratio, 1.19 per year; 95% confidence interval, 1.10 to 1.3; P<0.001), hospitalization within 30 days of death (odds ratio, 5.78; 95% confidence interval, 2.62 to 12.73; P<0.001), and death in hospital (odds ratio, 1.92; 95% confidence interval, 1.13 to 3.27; P=0.02).

CONCLUSIONS

In this single-center study, the rate of hemodialysis withdrawals were twice the frequency previously described. Acute medical complications and frailty appeared to be driving factors. However, palliative care services were used in only a minority of patients.

Death and Postoperative Complications After Hip Fracture Repair: Dialysis Effect

Introduction

It is unknown whether patients receiving dialysis have a higher morbidity and mortality risk after hip fracture repair conferred by their kidney failure or by the high comorbidity burden often present.

Methods

We examined associations of dialysis dependency with postoperative complications, death, and readmission in a matched cohort study of U.S. patients undergoing hip fracture repair, from January 2010 to December 2013, in the American College of Surgeons National Surgical Quality Improvement Program. Matching included sex, age, race, diabetes mellitus, operation year, primary surgery type, and anesthesia technique.

Results

Among 22,621 patients, 377 dialysis-dependent patients were matched to 1508 nondialysis patients. Median age was 78 years (interquartile range = 68−85) years, 56% were men, 70% were white, 43% had diabetes, and 47% underwent fracture fixation under mostly (80%) general anesthesia. Dialysis-dependent patients had higher physical status classification, had more heart failure and hypoalbuminemia, and were less often smokers. After adjustment, a greater risk of prolonged postoperative stays beyond 7 days (odds ratio [OR] = 1.43, 95% confidence interval [CI] = 1.09−1.89), higher in-hospital mortality (OR = 3.13, CI = 1.72−5.7), and 30-day death (OR = 2.29, CI = 1.51−3.48) but not 30-day readmission (P = 0.09) was observed with dialysis dependency. Adjusted analyses in the original cohort (n = 22,621) were similar: the dialysis group had greater risk of prolonged postoperative stay (OR = 1.77, CI = 1.42−2.21), in-hospital mortality (OR = 2.65, CI = 1.74−4.05), and 30-day death (OR = 2.03, CI = 1.48−2.80) and 30-day readmission (OR = 1.62, CI = 1.66−2.26).

Conclusion

Dialysis dependency is associated with an increased risk of death and postoperative complications after hip fracture repair. These findings have implications for case-mix adjustment and quality metrics.

Predictors of early mortality and readmissions among dialysis patients undergoing lower extremity amputation

OBJECTIVE

Patients receiving dialysis are at increased risk for lower extremity amputations (LEAs) and postoperative morbidity. Limited studies have examined differences in 30-day outcomes of mortality and health care use after amputation or the preoperative factors that relate to worsened outcomes in dialysis patients. Our objective was to examine dialysis dependency and other preoperative factors associated with readmission or death after LEA.

METHODS

A retrospective cohort study was conducted of dialysis-dependent and nondialysis patients undergoing major LEA in the 2012 to 2013 American College of Surgeons National Surgical Quality Improvement Program. Primary outcomes included death and hospital readmission within 30 days of amputation.

RESULTS

Of 6468 patients, 1166 (18%) were dialysis dependent. The dialysis cohort had more blacks (39% vs 23%), diabetes (76% vs 58%), below-knee amputations (62% vs 55%), and in-hospital deaths (8% vs 3%; all P < .001). The 30-day postoperative death rates (15% vs 7%) and readmission rates (35% vs 20% per 30 person-days; both P < .001) were higher in dialysis patients. Among the live discharges, the rate of any readmission or death within 30 days from amputation was highest in those aged ≥50 years (40% per 30 person-days). Multivariable analyses in the dialysis cohort revealed increased age, above-knee amputation, decreased physical status, heart failure, high preoperative white blood cell count, and low platelet count to be associated with death (P < .05; C statistic, 0.75). The only preoperative factor associated with readmission in dialysis patients was race (P = .04; C statistic, 0.58).

CONCLUSIONS

Readmission or death after amputation is increased among dialysis patients. Predicting which dialysis patients are at highest risk for death is feasible, whereas predicting which will require readmission is less so. Risk factor identification may improve risk stratification, inform reimbursement policies, and allow targeted interventions to improve outcomes.