An atlas of healthy and injured cell states and niches in the human kidney.

Understanding kidney disease relies on defining the complexity of cell types and states, their associated molecular profiles and interactions within tissue neighbourhoods1. Here we applied multiple single-cell and single-nucleus assays (>400,000 nuclei or cells) and spatial imaging technologies to a broad spectrum of healthy reference kidneys (45 donors) and diseased kidneys (48 patients). This has provided a high-resolution cellular atlas of 51 main cell types, which include rare and previously undescribed cell populations. The multi-omic approach provides detailed transcriptomic profiles, regulatory factors and spatial localizations spanning the entire kidney. We also define 28 cellular states across nephron segments and interstitium that were altered in kidney injury, encompassing cycling, adaptive (successful or maladaptive repair), transitioning and degenerative states. Molecular signatures permitted the localization of these states within injury neighbourhoods using spatial transcriptomics, while large-scale 3D imaging analysis (around 1.2 million neighbourhoods) provided corresponding linkages to active immune responses. These analyses defined biological pathways that are relevant to injury time-course and niches, including signatures underlying epithelial repair that predicted maladaptive states associated with a decline in kidney function. This integrated multimodal spatial cell atlas of healthy and diseased human kidneys represents a comprehensive benchmark of cellular states, neighbourhoods, outcome-associated signatures and publicly available interactive visualizations.

Efficacy and Safety of Allopurinol and Febuxostat in Patients With Gout and CKD: Subgroup Analysis of the STOP Gout Trial.

RATIONALE & OBJECTIVE: We conducted a prespecified examination of the efficacy and safety of allopurinol and febuxostat administered using a treat-to-target strategy in trial participants with chronic kidney disease (CKD). STUDY DESIGN: Prespecified subcohort analysis of a randomized controlled trial. SETTING & PARTICIPANTS: A substudy of the STOP Gout Trial in participants with CKD. CKD was defined as an estimated glomerular filtration rate (eGFR) 30-59mL/min/1.73m2 at baseline. EXPOSURE: Trial participants with CKD and gout and serum urate (SUA) concentration of≥6.8mg/dL were randomized 1:1 to receive allopurinol or febuxostat. Urate-lowering therapy (ULT) was titrated during weeks 0-24 to achieve a goal SUA of<6.0mg/dL (<5.0mg/dL with tophi) (phase 1) and maintained during weeks 25-48 (phase 2). Gout flare was assessed between weeks 49-72 (phase 3). OUTCOME: Gout flare between weeks 49-72 (phase 3) was the primary outcome. Secondary outcomes included SUA goal achievement and ULT dosing at end of phase 2, and serious adverse events. ANALYTICAL APPROACH: Outcomes between treatment groups were compared using logistic regression models for binary outcomes, and Poisson regression for flare rates. Multivariable models were subsequently used, adjusting for factors identified to be imbalanced by treatment arm. RESULTS: CKD was present in 351 of 940 participants; 277 were assessed for the primary outcome. Fewer patients randomized to allopurinol had a flare during phase 3 (32% vs 45%; P=0.02) despite similar attainment of the SUA goal (79% vs 81%; P=0.6) by the end of phase 2. Acute kidney injury was more common in participants with stage 3 CKD randomized to allopurinol compared with febuxostat. LIMITATIONS: Limited power to assess infrequent safety events, largely male, older population. CONCLUSIONS: Allopurinol and febuxostat are similarly efficacious and well-tolerated in the treatment of gout in people with CKD when used in a treat-to-target regimen with lower incidence of gout flares in participants randomized to allopurinol. PLAIN-LANGUAGE SUMMARY: The STOP Gout Trial was a multicenter, randomized, double-blind, noninferiority, comparative effectiveness trial, which found that allopurinol was noninferior to febuxostat in gout flare prevention and that both medications were similarly efficacious in reaching a serum urate goal when used as part of a treat-to-target approach. A significant proportion of patients with chronic kidney disease (CKD) are afflicted by gout, yet there is a lack of high-quality comparative effectiveness data comparing allopurinol and febuxostat in these patients. We evaluated the efficacy and safety of allopurinol and febuxostat in the subgroup of STOP Gout Trial participants with stage 3 CKD and found that allopurinol and febuxostat are similarly efficacious and well-tolerated in the treatment of gout in people with CKD when used in a treat-to-target regimen, with lower incidence of gout flares in participants randomized to allopurinol.

Utilization and Outcomes of Clinically Indicated Invasive Cardiac Care in Veterans with Acute Coronary Syndrome and Chronic Kidney Disease.

SIGNIFICANCE STATEMENT: Of studies reporting an association of CKD with lower use of invasive cardiac care to treat acute coronary syndrome (ACS), just one accounted for the appropriateness of such care. However, its findings in patients hospitalized nearly 30 years ago may not apply to current practice. In a more recent cohort of 64,695 veterans hospitalized with ACS, CKD was associated with a 32% lower likelihood of receiving invasive care determined to be clinically indicated. Among patients with CKD, not receiving such care was associated with a 1.39-fold higher risk of 6-month mortality. Efforts to elucidate the reasons for this disparity in invasive care in patients with ACS and CKD and implement tailored interventions to enhance its use in this population may offer the potential to improve clinical outcomes. BACKGROUND: Previous studies have shown that patients with CKD are less likely than those without CKD to receive invasive care to treat acute coronary syndrome (ACS). However, few studies have accounted for whether such care was clinically indicated or assessed whether nonuse of such care was associated with adverse health outcomes. METHODS: We conducted a retrospective cohort study of US veterans who were hospitalized at Veterans Affairs Medical Centers from January 2013 through December 2017 and received a discharge diagnosis of ACS. We used multivariable logistic regression to investigate the association of CKD with use of invasive care (coronary angiography, with or without revascularization; coronary artery bypass graft surgery; or both) deemed clinically indicated based on Global Registry of Acute Coronary Events 2.0 risk scores that denoted a 6-month predicted all-cause mortality ≥5%. Using propensity scoring and inverse probability weighting, we examined the association of nonuse of clinically indicated invasive care with 6-month all-cause mortality. RESULTS: Among 34,430 patients with a clinical indication for invasive care, the 18,780 patients with CKD were less likely than the 15,650 without CKD to receive such care (adjusted odds ratio, 0.68; 95% confidence interval, 0.65 to 0.72). Among patients with CKD, nonuse of invasive care was associated with higher risk of 6-month all-cause mortality (absolute risk, 21.5% versus 15.5%; absolute risk difference 6.0%; adjusted risk ratio, 1.39; 95% confidence interval, 1.29 to 1.49). Findings were consistent across multiple sensitivity analyses. CONCLUSIONS: In contemporary practice, veterans with CKD who experience ACS are less likely than those without CKD to receive clinically indicated invasive cardiac care. Nonuse of such care is associated with increased mortality.

Timing of Initiation of Renal-Replacement Therapy in Acute Kidney Injury.

BACKGROUND: Acute kidney injury is common in critically ill patients, many of whom receive renal-replacement therapy. However, the most effective timing for the initiation of such therapy remains uncertain. METHODS: We conducted a multinational, randomized, controlled trial involving critically ill patients with severe acute kidney injury. Patients were randomly assigned to receive an accelerated strategy of renal-replacement therapy (in which therapy was initiated within 12 hours after the patient had met eligibility criteria) or a standard strategy (in which renal-replacement therapy was discouraged unless conventional indications developed or acute kidney injury persisted for >72 hours). The primary outcome was death from any cause at 90 days. RESULTS: Of the 3019 patients who had undergone randomization, 2927 (97.0%) were included in the modified intention-to-treat analysis (1465 in the accelerated-strategy group and 1462 in the standard-strategy group). Of these patients, renal-replacement therapy was performed in 1418 (96.8%) in the accelerated-strategy group and in 903 (61.8%) in the standard-strategy group. At 90 days, death had occurred in 643 patients (43.9%) in the accelerated-strategy group and in 639 (43.7%) in the standard-strategy group (relative risk, 1.00; 95% confidence interval [CI], 0.93 to 1.09; P = 0.92). Among survivors at 90 days, continued dependence on renal-replacement therapy was confirmed in 85 of 814 patients (10.4%) in the accelerated-strategy group and in 49 of 815 patients (6.0%) in the standard-strategy group (relative risk, 1.74; 95% CI, 1.24 to 2.43). Adverse events occurred in 346 of 1503 patients (23.0%) in the accelerated-strategy group and in 245 of 1489 patients (16.5%) in the standard-strategy group (P<0.001). CONCLUSIONS: Among critically ill patients with acute kidney injury, an accelerated renal-replacement strategy was not associated with a lower risk of death at 90 days than a standard strategy. (Funded by the Canadian Institutes of Health Research and others; STARRT-AKI ClinicalTrials.gov number, NCT02568722.).

Fluid balance and renal replacement therapy initiation strategy: a secondary analysis of the STARRT-AKI trial.

BACKGROUND: Among critically ill patients with acute kidney injury (AKI), earlier initiation of renal replacement therapy (RRT) may mitigate fluid accumulation and confer better outcomes among individuals with greater fluid overload at randomization. METHODS: We conducted a pre-planned post hoc analysis of the STandard versus Accelerated initiation of Renal Replacement Therapy in Acute Kidney Injury (STARRT-AKI) trial. We evaluated the effect of accelerated RRT initiation on cumulative fluid balance over the course of 14 days following randomization using mixed models after censoring for death and ICU discharge. We assessed the modifying effect of baseline fluid balance on the impact of RRT initiation strategy on key clinical outcomes. Patients were categorized in quartiles of baseline fluid balance, and the effect of accelerated versus standard RRT initiation on clinical outcomes was assessed in each quartile using risk ratios (95% CI) for categorical variables and mean differences (95% CI) for continuous variables. RESULTS: Among 2927 patients in the modified intention-to-treat analysis, 2738 had available data on baseline fluid balance and 2716 (92.8%) had at least one day of fluid balance data following randomization. Over the subsequent 14 days, participants allocated to the accelerated strategy had a lower cumulative fluid balance compared to those in the standard strategy (4509 (- 728 to 11,698) versus 5646 (0 to 13,151) mL, p = 0.03). Accelerated RRT initiation did not confer greater 90-day survival in any of the baseline fluid balance quartiles (quartile 1: RR 1.11 (95% CI 0.92 to 1.34), quartile 2: RR 1.03 (0.87 to 1.21); quartile 3: RR 1.08 (95% CI 0.91 to 1.27) and quartile 4: RR 0.87 (95% CI 0.73 to 1.03), p value for trend 0.08). CONCLUSIONS: Earlier RRT initiation in critically ill patients with AKI conferred a modest attenuation of cumulative fluid balance. Nonetheless, among patients with greater fluid accumulation at randomization, accelerated RRT initiation did not have an impact on all-cause mortality. TRIAL REGISTRATION: ClinicalTrials.gov number, https://clinicaltrials.gov/ct2/show/NCT02568722 , registered October 6, 2015.

Association between Net Ultrafiltration Rate and Renal Recovery among Critically Ill Adults with Acute Kidney Injury Receiving Continuous Renal Replacement Therapy: An Observational Cohort Study.

INTRODUCTION: Higher net ultrafiltration (UFNET) rates are associated with mortality among critically ill patients with acute kidney injury (AKI) and treated with continuous renal replacement therapy (CRRT). OBJECTIVE: The aim of the study was to discover whether UFNET rates are associated with renal recovery and independence from renal replacement therapy (RRT). METHODS: Retrospective cohort study using data from the Randomized Evaluation of Normal versus Augmented Level of Renal Replacement Therapy trial that enrolled 1,433 critically ill patients with AKI and treated with CRRT between December 2005 and November 2008 across 35 intensive care units in Australia and New Zealand. We examined the association between UFNET rate and time to independence from RRT by day 90 using competing risk regression after accounting for mortality. The UFNET rate was defined as the volume of fluid removed per hour adjusted for patient body weight. RESULTS AND CONCLUSIONS: Median age was 67.3 (interquartile range [IQR], 57-76.3) years, 64.4% were male, median Acute Physiology and Chronic Health Evaluation-III score was 100 (IQR, 84-118), and 634 (44.2%) died by day 90. Kidney recovery occurred in 755 patients (52.7%). Using tertiles of UFNET rates, 3 groups were defined: high, >1.75; middle, 1.01-1.75; and low, <1.01 mL/kg/h. Proportion of patients alive and independent of RRT among the groups were 47.8 versus 57.2 versus 53.0%; p = 0.01. Using competing risk regression, higher UFNET rate tertile compared with middle (cause-specific hazard ratio [csHR], 0.79, 95% CI, 0.66-0.95; subdistribution hazard ratio [sHR], 0.80, 95% CI, 0.67-0.97) and lower (csHR, 0.69, 95% CI, 0.56-0.85; sHR, 0.78, 95% CI 0.64-0.95) tertiles were associated with a longer time to independence from RRT. Every 1.0 mL/kg/h increase in rate was associated with a lower probability of kidney recovery (csHR, 0.81, 95% CI, 0.74-0.89; and sHR, 0.87, 95% CI, 0.80-0.95). Using the joint model, longitudinal increases in UFNET rates were also associated with a lower renal recovery (ß = -0.29, p < 0.001). UFNET rates >1.75 mL/kg/h compared with rates 1.01-1.75 and <1.01 mL/kg/h were associated with a longer duration of dependence on RRT. Randomized clinical trials are required to confirm this UFNET rate-outcome relationship.

Suggestions for the prevention of Clostridioides difficile spread within outpatient hemodialysis facilities.

Clostridioides difficile infections (CDIs) cause substantial morbidity and mortality. Patients on maintenance hemodialysis are 2 to 2.5 times more likely to develop CDI, with mortality rates 2-fold higher than the general population. Hospitalizations due to CDI among the maintenance hemodialysis population are high, and the frequency of antibiotic exposures and hospitalizations may contribute to CDI risk. In this report, a panel of experts in clinical nephrology, infectious diseases, and infection prevention provide guidance, based on expert opinion and published literature, aimed at preventing the spread of CDI in outpatient hemodialysis facilities.

Rationale and design of the Kidney Precision Medicine Project.

Chronic kidney disease (CKD) and acute kidney injury (AKI) are common, heterogeneous, and morbid diseases. Mechanistic characterization of CKD and AKI in patients may facilitate a precision-medicine approach to prevention, diagnosis, and treatment. The Kidney Precision Medicine Project aims to ethically and safely obtain kidney biopsies from participants with CKD or AKI, create a reference kidney atlas, and characterize disease subgroups to stratify patients based on molecular features of disease, clinical characteristics, and associated outcomes. An additional aim is to identify critical cells, pathways, and targets for novel therapies and preventive strategies. This project is a multicenter prospective cohort study of adults with CKD or AKI who undergo a protocol kidney biopsy for research purposes. This investigation focuses on kidney diseases that are most prevalent and therefore substantially burden the public health, including CKD attributed to diabetes or hypertension and AKI attributed to ischemic and toxic injuries. Reference kidney tissues (for example, living-donor kidney biopsies) will also be evaluated. Traditional and digital pathology will be combined with transcriptomic, proteomic, and metabolomic analysis of the kidney tissue as well as deep clinical phenotyping for supervised and unsupervised subgroup analysis and systems biology analysis. Participants will be followed prospectively for 10 years to ascertain clinical outcomes. Cell types, locations, and functions will be characterized in health and disease in an open, searchable, online kidney tissue atlas. All data from the Kidney Precision Medicine Project will be made readily available for broad use by scientists, clinicians, and patients.

Outcomes after Angiography with Sodium Bicarbonate and Acetylcysteine.

BACKGROUND: Intravenous sodium bicarbonate and oral acetylcysteine are widely used to prevent acute kidney injury and associated adverse outcomes after angiography without definitive evidence of their efficacy. METHODS: Using a 2-by-2 factorial design, we randomly assigned 5177 patients at high risk for renal complications who were scheduled for angiography to receive intravenous 1.26% sodium bicarbonate or intravenous 0.9% sodium chloride and 5 days of oral acetylcysteine or oral placebo; of these patients, 4993 were included in the modified intention-to-treat analysis. The primary end point was a composite of death, the need for dialysis, or a persistent increase of at least 50% from baseline in the serum creatinine level at 90 days. Contrast-associated acute kidney injury was a secondary end point. RESULTS: The sponsor stopped the trial after a prespecified interim analysis. There was no interaction between sodium bicarbonate and acetylcysteine with respect to the primary end point (P=0.33). The primary end point occurred in 110 of 2511 patients (4.4%) in the sodium bicarbonate group as compared with 116 of 2482 (4.7%) in the sodium chloride group (odds ratio, 0.93; 95% confidence interval [CI], 0.72 to 1.22; P=0.62) and in 114 of 2495 patients (4.6%) in the acetylcysteine group as compared with 112 of 2498 (4.5%) in the placebo group (odds ratio, 1.02; 95% CI, 0.78 to 1.33; P=0.88). There were no significant between-group differences in the rates of contrast-associated acute kidney injury. CONCLUSIONS: Among patients at high risk for renal complications who were undergoing angiography, there was no benefit of intravenous sodium bicarbonate over intravenous sodium chloride or of oral acetylcysteine over placebo for the prevention of death, need for dialysis, or persistent decline in kidney function at 90 days or for the prevention of contrast-associated acute kidney injury. (Funded by the U.S. Department of Veterans Affairs Office of Research and Development and the National Health and Medical Research Council of Australia; PRESERVE ClinicalTrials.gov number, NCT01467466 .).

Kidney-Related Research in the United States: A Position Statement From the National Kidney Foundation and the American Society of Nephrology.

Kidney disease is an important US public health problem because it affects over 37 million Americans, and Medicare expenditures for patients with chronic kidney disease now alone exceed $130 billion annually. Kidney disease is characterized by strong racial, ethnic, and socioeconomic disparities, and reducing kidney disease incidence will positively impact US health disparities. Due to the aging of the US population and an unabated obesity epidemic, the number of patients receiving treatment for kidney failure is anticipated to increase, which will escalate kidney disease health expenditures. The historical and current investment in kidney-related research via the National Institute of Diabetes and Digestive and Kidney Diseases has severely lagged behind ongoing expenditures for kidney disease care. Increasing research investment will identify, develop, and increase implementation of interventions to slow kidney disease progression, reduce incidence of kidney failure, enhance survival, and improve quality of life. This perspective states the urgent reasons why increasing investment in kidney-related research is important for US public health. The National Kidney Foundation and the American Society of Nephrology are working together to advocate for increased funding for the National Institute of Diabetes and Digestive and Kidney Diseases. The long-term goal is to reduce the burden of kidney disease in the US population and improve the quality of life of patients living with kidney disease.

Serial Measurement of Cell-Cycle Arrest Biomarkers [TIMP-2] · [IGFBP7] and Risk for Progression to Death, Dialysis, or Severe Acute Kidney Injury in Patients with Septic Shock.

Rationale: Urinary TIMP-2 (tissue inhibitor of metalloproteinases-2) and IGFBP7 (insulin-like growth factor-binding protein 7) can predict acute kidney injury (AKI) in patients with sepsis.Objectives: To address critical questions about whether biomarkers can inform the response to treatment and whether they might be used to guide therapy, as most sepsis patients present with AKI.Methods: We measured [TIMP-2] · [IGFBP7] before and after a 6-hour resuscitation in 688 patients with septic shock enrolled in the ProCESS (Protocol-based Care for Early Septic Shock) trial. Our primary endpoint was stage 3 AKI, renal replacement therapy, or death within 7 days.Measurements and Main Results: The endpoint was reached in 113 patients (16.4%). In patients with negative [TIMP-2] · [IGFBP7] at baseline, those who became positive (>0.3 U) after resuscitation had three-times higher risk compared with those who remained negative (21.8% vs. 8.5%; P = 0.01; odds ratio [OR], 3.0; 95% confidence interval [CI], 1.31-6.87). Conversely, compared with patients with a positive biomarker at baseline that were still positive at Hour 6, risk was reduced for patients who became negative (23.8% vs. 9.8%; P = 0.01; OR, 2.15; 95% CI, 1.17-3.95). A positive [TIMP-2] · [IGFBP7] after resuscitation was associated with worse outcomes in both patients with and without AKI at that time point. The clinical response to resuscitation, as judged by the Acute Physiology and Chronic Health Evaluation II score, was weakly predictive of the endpoint (area under the curve, 0.68; 95% CI, 0.62-0.73) and improved with addition of [TIMP-2] · [IGFBP7] (0.72; 95% CI, 0.66-0.77; P = 0.03). Different resuscitation protocols did not alter biomarker trajectories, nor did they alter outcomes in biomarker-positive or biomarker-negative patients. However, biomarker trajectories were associated with outcomes.Conclusions: Changes in urinary [TIMP-2] · [IGFBP7] after initial fluid resuscitation identify patients with sepsis who have differing risk for progression of AKI.Clinical trial registered with www.clinicaltrials.gov (NCT00510835).

Nomenclature for kidney function and disease: report of a Kidney Disease: Improving Global Outcomes (KDIGO) Consensus Conference.

The worldwide burden of kidney disease is rising, but public awareness remains limited, underscoring the need for more effective communication by stakeholders in the kidney health community. Despite this need for clarity, the nomenclature for describing kidney function and disease lacks uniformity. In June 2019, Kidney Disease: Improving Global Outcomes (KDIGO) convened a Consensus Conference with the goal of standardizing and refining the nomenclature used in the English language to describe kidney function and disease, and of developing a glossary that could be used in scientific publications. Guiding principles of the conference were that the revised nomenclature should be patient-centered, precise, and consistent with nomenclature used in the KDIGO guidelines. Conference attendees reached general consensus on the following recommendations: (i) to use "kidney" rather than "renal" or "nephro-" when referring to kidney disease and kidney function; (ii) to use "kidney failure" with appropriate descriptions of presence or absence of symptoms, signs, and treatment, rather than "end-stage kidney disease"; (iii) to use the KDIGO definition and classification of acute kidney diseases and disorders (AKD) and acute kidney injury (AKI), rather than alternative descriptions, to define and classify severity of AKD and AKI; (iv) to use the KDIGO definition and classification of chronic kidney disease (CKD) rather than alternative descriptions to define and classify severity of CKD; and (v) to use specific kidney measures, such as albuminuria or decreased glomerular filtration rate (GFR), rather than "abnormal" or "reduced" kidney function to describe alterations in kidney structure and function. A proposed 5-part glossary contains specific items for which there was general agreement. Conference attendees acknowledged limitations of the recommendations and glossary, but they considered standardization of scientific nomenclature to be essential for improving communication.

Net Ultrafiltration Prescription and Practice Among Critically Ill Patients Receiving Renal Replacement Therapy: A Multinational Survey of Critical Care Practitioners.

OBJECTIVES: To assess the attitudes of practitioners with respect to net ultrafiltration prescription and practice among critically ill patients with acute kidney injury treated with renal replacement therapy. DESIGN: Multinational internet-assisted survey. SETTING: Critical care practitioners involved with 14 societies in 80 countries. SUBJECTS: Intervention: MEASUREMENT AND MAIN RESULTS:: Of 2,567 practitioners who initiated the survey, 1,569 (61.1%) completed the survey. Most practitioners were intensivists (72.7%) with a median duration of 13.2 years of practice (interquartile range, 7.2-22.0 yr). Two third of practitioners (71.0%; regional range, 55.0-95.5%) reported using continuous renal replacement therapy with a net ultrafiltration rate prescription of median 80.0 mL/hr (interquartile range, 49.0-111.0 mL/hr) for hemodynamically unstable and a maximal rate of 299.0 mL/hr (interquartile range, 200.0-365.0 mL/hr) for hemodynamically stable patients, with regional variation. Only a third of practitioners (31.5%; range, 13.7-47.8%) assessed hourly net fluid balance during continuous renal replacement therapy. Hemodynamic instability was reported in 20% (range, 20-38%) of patients and practitioners decreased the rate of fluid removal (70.3%); started or increased the dose of a vasopressor (51.5%); completely stopped fluid removal (35.8%); and administered a fluid bolus (31.6%), with significant regional variation. Compared with physicians, nurses were most likely to report patient intolerance to net ultrafiltration (73.4% vs 81.3%; p = 0.002), frequent interruptions (40.4% vs 54.5%; p < 0.001), and unavailability of trained staff (11.9% vs 15.6%; p = 0.04), whereas physicians reported unavailability of dialysis machines (14.3% vs 6.1%; p < 0.001) and costs associated with treatment as barriers (12.1% vs 3.0%; p < 0.001) with significant regional variation. CONCLUSIONS: Our study provides new knowledge about the presence and extent of international practice variation in net ultrafiltration. We also identified barriers and specific targets for quality improvement initiatives. Our data reflect the need for evidence-based practice guidelines for net ultrafiltration.

Kidney Biomarkers of Injury and Repair as Predictors of Contrast-Associated AKI: A Substudy of the PRESERVE Trial.

RATIONALE & OBJECTIVE: The PRESERVE trial used a 2 × 2 factorial design to compare intravenous saline solution with intravenous sodium bicarbonate solution and oral N-acetylcysteine with placebo for the prevention of 90-day major adverse kidney events and death (MAKE-D) and contrast-associated acute kidney injury (CA-AKI) among patients with chronic kidney disease undergoing angiography. In this ancillary study, we evaluated the predictive capacities of preangiography injury and repair proteins in urine and plasma for MAKE-D, CA-AKI, and their impact on trial design. STUDY DESIGN: Longitudinal analysis. SETTING & PARTICIPANTS: A subset of participants from the PRESERVE trial. EXPOSURES: Injury (KIM-1, NGAL, and IL-18) and repair (MCP-1, UMOD, and YKL-40) proteins in urine and plasma 1 to 2 hours preangiography. OUTCOMES: MAKE-D and CA-AKI. ANALYTICAL APPROACH: We analyzed the associations of preangiography biomarkers with MAKE-D and with CA-AKI. We evaluated whether the biomarker levels could enrich the MAKE-D event rate and improve future clinical trial efficiency through an online biomarker prognostic enrichment tool available at prognosticenrichment.com. RESULTS: We measured plasma biomarkers in 916 participants and urine biomarkers in 797 participants. After adjusting for urinary albumin-creatinine ratio and baseline estimated glomerular filtration rate, preangiography levels of 4 plasma (KIM-1, NGAL, UMOD, and YKL-40) and 3 urine (NGAL, IL-18, and YKL-40) biomarkers were associated with MAKE-D. Only plasma KIM-1 level was significantly associated with CA-AKI after adjustment. Biomarker levels provided modest discriminatory capacity for MAKE-D. Screening patients using the 50th percentile of preangiography plasma KIM-1 or YKL-40 levels would have reduced the required sample size by 30% (∼2,000 participants). LIMITATIONS: Evaluation of prognostic enrichment does not account for changing trial costs, time needed to screen patients, or loss to follow-up. Most participants were male, limiting the generalizability of our findings. CONCLUSIONS: Preangiography levels of injury and repair biomarkers modestly predict the development of MAKE-D and can be used to improve the efficiency of future CA-AKI trials.

A Simple Equation to Estimate Urinary Flow Rate Using Urine Creatinine.

BACKGROUND: Accurate assessment of urine flow remains challenging in both inpatient and outpatient settings. We hypothesized we could derive an equation that would accurately estimate urine flow rate (eV) through derivation from other existing equations commonly used in nephrology clinical practice. METHODS: The eV equation was derived using the Cockcroft-Gault and the measured creatinine clearance (CrCl = UCrV/PCr) equations. Within the African American Study of Kidney Disease and Hypertension (AASK; n = 570) and COMBINE (n = 133) clinical trials, we identified participants with concordant estimated and measured creatinine excretion rates to define a subset with highly accurate 24-h urine collections, to assure a reliable gold standard. We then compared eV to measured 24-h urine flow rates in these trials. RESULTS: In AASK, we found a high correlation between eV and measured urine flow rate (V; r = 0.91, p < 0.001); however, Bland-Altman plots showed that eV was 9.5 mL/h lower than V, on average. Thus, we added a correction factor to the eV equation and externally validated the new equation in COMBINE. eV and V were again highly correlated (r = 0.91, p < 0.001), and bias was improved (mean difference 5.3 mL/h). Overall, 80% of individuals had eV that was within 20% of V. CONCLUSIONS: A simple equation using urine creatinine, demographics, and body weight can accurately predict urine flow rate and may have clinical utility in situations where it is difficult to accurately measure the urine flow rate.

Development, implementation and user experience of the Veterans Health Administration (VHA) dialysis dashboard.

BACKGROUND: Adults with end-stage renal disease (ESRD) requiring chronic dialysis continue to suffer from poor health outcomes and represent a population rightfully targeted for quality improvement. Electronic dashboards are increasingly used in healthcare to facilitate quality measurement and improvement. However, detailed descriptions of the creation of healthcare dashboards are uncommonly available and formal inquiry into perceptions, satisfaction, and utility by clinical users has been rarely conducted, particularly in the context of dialysis care. Therefore, we characterized the development, implementation and user experience with Veterans Health Administration (VHA) dialysis dashboard. METHODS: A clinical-quality dialysis dashboard was implemented, which displays clinical performance measures (CPMs) for Veterans with ESRD receiving chronic hemodialysis at all VHA facilities. Data on user experience and perceptions were collected via an e-mail questionnaire to dialysis medical directors and nurse managers at these facilities. RESULTS: Since 2016 the dialysis dashboard reports monthly on CPMs for approximately 3000 Veterans receiving chronic hemodialysis across 70 VHA dialysis facilities. Of 141 dialysis medical directors and nurse managers, 61 completed the questionnaire. Sixty-six percent of respondents did not find the dashboard difficult to access, 64% agreed that it is easy to use, 59% agreed that its layout is good, and the majority agreed that presentation of data is clear (54%), accurate (56%), and up-to-date (54%). Forty-eight percent of respondents indicated that it helped them improve patient care while 12% did not. Respondents indicated that they used the dialysis dashboard for clinical reporting (71%), quality assessment/performance improvement (QAPI) (62%), and decision-making (23%). CONCLUSIONS: Most users of the VHA dialysis dashboard found it accurate, up-to-date, easy to use, and helpful in improving patient care. It meets diverse user needs, including administrative reporting, clinical benchmarking and decision-making, and quality assurance and performance improvement (QAPI) activities. Moreover, the VHA dialysis dashboard affords national-, regional- and facility-level assessments of quality of care, guides and motivates best clinical practices, targets QAPI efforts, and informs and promotes population health management improvement efforts for Veterans receiving chronic hemodialysis.

Iron, Hepcidin, and Death in Human AKI.

BACKGROUND: Iron is a key mediator of AKI in animal models, but data on circulating iron parameters in human AKI are limited. METHODS: We examined results from the ARF Trial Network study to assess the association of plasma catalytic iron, total iron, transferrin, ferritin, free hemoglobin, and hepcidin with 60-day mortality. Participants included critically ill patients with AKI requiring RRT who were enrolled in the study. RESULTS: Of the 807 study participants, 409 (51%) died by day 60. In both unadjusted and multivariable adjusted models, higher plasma concentrations of catalytic iron were associated with a significantly greater risk of death, as were lower concentrations of hepcidin. After adjusting for other factors, patients with catalytic iron levels in the highest quintile versus the lowest quintile had a 4.06-fold increased risk of death, and patients with hepcidin levels in the lowest quintile versus the highest quintile of hepcidin had a 3.87-fold increased risk of death. These findings were consistent across multiple subgroups. Other iron markers were also associated with death, but the magnitude of the association was greatest for catalytic iron and hepcidin. Higher plasma concentrations of catalytic iron and lower concentrations of hepcidin are each independently associated with mortality in critically ill patients with AKI requiring RRT. CONCLUSIONS: These findings suggest that plasma concentrations of catalytic iron and hepcidin may be useful prognostic markers in patients with AKI. Studies are needed to determine whether strategies to reduce catalytic iron or increase hepcidin might be beneficial in this patient population.

Urea reduction ratio may be a simpler approach for measurement of adequacy of intermittent hemodialysis in acute kidney injury.

BACKGROUND: Assessment of adequacy of intermittent hemodialysis (IHD) is conventionally based upon urea kinetic models for calculation of single pool Kt/Vurea (Kt/V), with 1.2 accepted as minimum adequate clearance for thrice weekly IHD. In the Acute Renal Failure Trial Network (ATN) Study, adequacy of IHD in patients with acute kidney injury (AKI) was assessed using Kt/V. However, equations for Kt/V require volume of distribution of urea, which is highly variable in AKI. Therefore, simpler methods are needed to assess adequacy of IHD in AKI. We assessed correlation of urea reduction ratio (URR) with Kt/V and determined URR thresholds corresponding to Kt/V values to determine if URR could be a simpler means to assess the delivered dose of IHD. METHODS: Using patients who received IHD for 2.5-6 h and with pre-dialysis BUN ≥20 mg/dL, we plotted URR against Kt/V. We determined URR thresholds (0.60 to 0.75) corresponding to Kt/V ≥ 1.2, 1.3, and 1.4. We generated receiver operating characteristic (ROC) curves for increasing URR values for each level of Kt/V to identify the corresponding thresholds of URR. RESULTS: There was strong correlation between URR and Kt/V. ROC curves comparing URR with Kt/V ≥ 1.2, 1.3, and 1.4 had area under the curves (AUC) of 0.99. Sensitivity and specificity of URR ≥0.67 for corresponding values of Kt/V ≥ 1.2 were 0.769 (95% CI: 0.745 to 0.793) and 0.999 (95% CI: 0.997 to 1.000), respectively and the sensitivity and specificity of URR ≥0.67 for corresponding values of Kt/V ≥ 1.4 were 0.998 (95% CI: 0.995 to 1.000) and 0.791 (95% CI: 0.771 to 0.811), respectively. CONCLUSIONS: Targeting a URR ≥0.67 provides a simplified means of assessing adequacy of IHD in patients with AKI. Use of URR will enhance ability to assess delivery of small solute clearance and improve adherence with clinical practice guidelines in AKI.