CureGN Study Rationale, Design, and Methods: Establishing a Large Prospective Observational Study of Glomerular Disease

Comparing adolescent glomerular disease clinical outcomes to the clinical outcomes in childhood, young adult, and adult-onset glomerular disease in the CureGN database

BACKGROUND

There is a lack of evidence to suggest that outcomes of adolescent and adult-onset glomerular disease differ. Still, most glomerular disease trials include adults but exclude adolescents.

METHODS

We designed a retrospective study using the CureGN database to compare individuals with adolescent-onset glomerular disease relative to individuals with older and younger age at onset. The two main outcomes were sustained proteinuria remission off immunosuppression treatment and composite eGFR decline.

RESULTS

Our data did not show a significant difference in sustained proteinuria remission off treatment or composite eGFR decline between adolescent onset glomerular disease and either childhood (age 5-12), young adult (age 20-29), or adult (age 30-39) onset glomerular disease. Having high-risk APOL1 alleles and hypertension at the time of study enrollment decreased the likelihood of achieving sustained proteinuria remission off treatment. While participants with minimal change disease and IgA nephropathy were similarly likely to achieve sustained proteinuria remission off treatment, participants with focal segmental glomerulosclerosis and membranous nephropathy were less likely to achieve sustained proteinuria remission off treatment compared to participants with minimal change disease. CKD stage, high-risk APOL1 alleles, hypertension stage, and education all significantly impacted the likelihood of progression to the composite eGFR decline outcome.

CONCLUSIONS

Approximately 25% of each age cohort reached the composite eGFR decline outcome within 5 years. As more glomerular disease clinical trials become available, we must consider opening these trials to people with childhood and adolescent onset disease since like adults they are at high risk of progressive kidney function decline.

Spatial transcriptomics in health and disease

The ability to localize hundreds of macromolecules to discrete locations, structures and cell types in a tissue is a powerful approach to understand the cellular and spatial organization of an organ. Spatially resolved transcriptomic technologies enable mapping of transcripts at single-cell or near single-cell resolution in a multiplex manner. The rapid development of spatial transcriptomic technologies has accelerated the pace of discovery in several fields, including nephrology. Its application to preclinical models and human samples has provided spatial information about new cell types discovered by single-cell sequencing and new insights into the cell-cell interactions within neighbourhoods, and has improved our understanding of the changes that occur in response to injury. Integration of spatial transcriptomic technologies with other omics methods, such as proteomics and spatial epigenetics, will further facilitate the generation of comprehensive molecular atlases, and provide insights into the dynamic relationships of molecular components in homeostasis and disease. This Review provides an overview of current and emerging spatial transcriptomic methods, their applications and remaining challenges for the field.

Natural History and Clinicopathological Associations of TRPC6-Associated Podocytopathy

Key Points

Background

Understanding the genetic basis of human diseases has become integral to drug development and precision medicine. Recent advancements have enabled the identification of molecular pathways driving diseases, leading to targeted treatment strategies. The increasing investment in rare diseases by the biotech industry underscores the importance of genetic evidence in drug discovery and approval processes. Here we studied a monogenic Mendelian kidney disease, TRPC6-associated podocytopathy (TRPC6-AP), to present its natural history, genetic spectrum, and clinicopathological associations in a large cohort of patients with causal variants in TRPC6 to help define the specific features of disease and further facilitate drug development and clinical trials design.

Methods

The study involved 64 individuals from 39 families with TRPC6 causal missense variants. Clinical data, including age of onset, laboratory results, response to treatment, kidney biopsy findings, and genetic information, were collected from multiple centers nationally and internationally. Exome or targeted sequencing was performed, and variant classification was based on strict criteria. Structural and functional analyses of TRPC6 variants were conducted to understand their effect on protein function. In-depth reanalysis of light and electron microscopy specimens for nine available kidney biopsies was conducted to identify pathological features and correlates of TRPC6-AP.

Results

Large-scale sequencing data did not support causality for TRPC6 protein-truncating variants. We identified 21 unique TRPC6 missense variants, clustering in three distinct regions of the protein, and with different effects on TRPC6 3D protein structure. Kidney biopsy analysis revealed FSGS patterns of injury in most cases, along with distinctive podocyte features including diffuse foot process effacement and swollen cell bodies. Most patients presented in adolescence or early adulthood but with ample variation (average 22, SD ±14 years), with frequent progression to kidney failure but with variability in time between presentation and kidney failure.

Conclusions

This study provides insights into the genetic spectrum, clinicopathological associations, and natural history of TRPC6-AP.

Clinical Trial registry name and registration number:

A Study to Test BI 764198 in People With a Type of Kidney Disease Called Focal Segmental Glomerulosclerosis, NCT05213624.

Increased risk of kidney failure in patients with genetic kidney disorders

BACKGROUNDIt is unknown whether the risk of kidney disease progression and failure differs between patients with and without genetic kidney disorders.METHODSThree cohorts were evaluated: the prospective Cure Glomerulonephropathy Network (CureGN) and 2 retrospective cohorts from Columbia University, including 5,727 adults and children with kidney disease from any etiology who underwent whole-genome or exome sequencing. The effects of monogenic kidney disorders and APOL1 kidney-risk genotypes on the risk of kidney failure, estimated glomerular filtration rate (eGFR) decline, and disease remission rates were evaluated along with diagnostic yields and the impact of American College of Medical Genetics secondary findings (ACMG SFs).RESULTSMonogenic kidney disorders were identified in 371 patients (6.5%), high-risk APOL1 genotypes in 318 (5.5%), and ACMG SFs in 100 (5.2%). Family history of kidney disease was the strongest predictor of monogenic disorders. After adjustment for traditional risk factors, monogenic kidney disorders were associated with an increased risk of kidney failure (hazard ratio [HR] = 1.72), higher rate of eGFR decline (-3.06 vs. 0.25 mL/min/1.73 m2/year), and lower risk of complete remission (odds ratioNot achieving CR = 5.25). High-risk APOL1 genotypes were associated with an increased risk of kidney failure (HR = 1.67) and faster eGFR decline (-2.28 vs. 0.25 mL/min/1.73 m2), replicating prior findings. ACMG SFs were not associated with personal or family history of associated diseases, but were predicted to impact care in 70% of cases.CONCLUSIONSMonogenic kidney disorders were associated with an increased risk of kidney failure, faster eGFR decline, and lower rates of complete remission, suggesting opportunities for early identification and intervention based on molecular diagnosis.TRIAL REGISTRATIONNA.FUNDINGNational Institute of Diabetes and Digestive and Kidney Diseases grants U24DK100845 (formerly UM1DK100845), U01DK100846 (formerly UM1DK100846), U01DK100876 (formerly UM1DK100876), U01DK100866 (formerly UM1DK100866), U01DK100867 (formerly UM1DK100867), U24DK100845, DK081943, RC2DK116690, 2U01DK100876, 1R01DK136765, 5R01DK082753, and RC2-DK122397; NephCure Kidney International; Department of Defense Research Awards PR201425, W81XWH-16-1-0451, and W81XWH-22-1-0966; National Center for Advancing Translational Sciences grant UL1TR001873; National Library of Medicine grant R01LM013061; National Human Genome Research Institute grant 2U01HG008680.

Characterization of arteriosclerosis based on computer-aided measurements of intra-arterial thickness

Purpose

Our purpose is to develop a computer vision approach to quantify intra-arterial thickness on digital pathology images of kidney biopsies as a computational biomarker of arteriosclerosis.

Approach

The severity of the arteriosclerosis was scored (0 to 3) in 753 arteries from 33 trichrome-stained whole slide images (WSIs) of kidney biopsies, and the outer contours of the media, intima, and lumen were manually delineated by a renal pathologist. We then developed a multi-class deep learning (DL) framework for segmenting the different intra-arterial compartments (training dataset: 648 arteries from 24 WSIs; testing dataset: 105 arteries from 9 WSIs). Subsequently, we employed radial sampling and made measurements of media and intima thickness as a function of spatially encoded polar coordinates throughout the artery. Pathomic features were extracted from the measurements to collectively describe the arterial wall characteristics. The technique was first validated through numerical analysis of simulated arteries, with systematic deformations applied to study their effect on arterial thickness measurements. We then compared these computationally derived measurements with the pathologists' grading of arteriosclerosis.

Results

Numerical validation shows that our measurement technique adeptly captured the decreasing smoothness in the intima and media thickness as the deformation increases in the simulated arteries. Intra-arterial DL segmentations of media, intima, and lumen achieved Dice scores of 0.84, 0.78, and 0.86, respectively. Several significant associations were identified between arteriosclerosis grade and pathomic features using our technique (e.g., intima-media ratio average [ τ = 0.52 , p < 0.0001 ]) through Kendall's tau analysis.

Conclusions

We developed a computer vision approach to computationally characterize intra-arterial morphology on digital pathology images and demonstrate its feasibility as a potential computational biomarker of arteriosclerosis.

Association of Obesity With Kidney and Cardiac Outcomes Among Patients With Glomerular Disease: Findings From the Cure Glomerulonephropathy Network

RATIONALE & OBJECTIVE

The influence of obesity on cardiorenal outcomes in individuals with glomerular disease is incompletely known. This study examined the association between obesity and kidney and cardiovascular outcomes in children and adults with glomerular kidney disease.

STUDY DESIGN

Prospective, multicenter, observational study.

SETTING & PARTICIPANTS

Participants in the Cure Glomerulonephropathy Network (CureGN) who were≥5 years of age at enrollment.

EXPOSURE

Adult body mass index (BMI) groups: 20-24 (healthy) versus 25-34 (overweight/class 1 obesity) versus≥35 (class 2-3 obesity); and pediatric BMI percentiles: 5th-84th (healthy) versus 85th-94th (overweight) versus≥95th (obese).

OUTCOME

A composite kidney outcome (40% estimated glomerular filtration rate [eGFR] decline or kidney failure) and a composite cardiovascular outcome (myocardial infarction, stroke, heart failure, or death).

ANALYTICAL APPROACH

Time to composite primary outcomes by BMI strata were estimated using Kaplan-Meier analysis. The adjusted associations between BMI and outcomes were estimated using Cox proportional hazards analysis.

RESULTS

The study included 2,301 participants (1,548 adults and 753 children). The incidence of the primary kidney end point was 90.8 per 1,000 person-years in adults with class 2-3 obesity, compared with 58.0 in normal weight comparators. In the univariable analysis, class 2-3 obesity was associated with the primary kidney outcome only in adults (HR, 1.6 [95% CI, 1.1-2.2], P=0.006) compared with the healthy weight groups. In the multivariable adjusted analysis, class 2-3 obesity did not remain significant among adults when controlling for baseline eGFR and proteinuria. Adults with class 2-3 obesity had an incidence of 19.7 cardiovascular events per 1,000 person-years and greater cardiovascular risk (HR, 3.9 [95% CI, 1.4-10.7], P=0.009) in the fully adjusted model.

LIMITATIONS

BMI is an imperfect indicator of adiposity. Residual confounding may exist from socioeconomic factors.

CONCLUSIONS

Among adult patients in CureGN, class 2-3 obesity is associated with cardiovascular but not kidney outcomes when adjusted for potential confounding factors.

PLAIN-LANGUAGE SUMMARY

Obesity is a risk factor for adverse heart and kidney outcomes in patients with chronic kidney disease, but whether it is associated with these outcomes in patients with glomerulonephropathy is not known. This study used existing data from a large sample of adults and children with glomerular diseases to address this question. The findings suggest that obesity increases the risk of cardiovascular but not kidney disease events in adult patients with glomerular disease.

Association of Preterm Birth with Adverse Glomerular Disease Outcomes in Children and Adults

Key Points

Preterm birth was a risk factor for adverse outcomes in this heterogeneous cohort of children and adults with glomerular disease. In analyses adjusted for diagnosis and apolipoprotein L1 risk status, there was less remission and faster progression of kidney disease in those born preterm. A novel finding from this study is that adults born preterm were more likely to have an apolipoprotein L1 high-risk genotype.

Background

While some studies of children with nephrotic syndrome have demonstrated worse outcomes in those born preterm compared with term, little data exist on associations of preterm birth with outcomes in adult-onset glomerular disease. Cardiovascular outcomes in those born preterm with glomerular disease are unknown.

Methods

We performed a cross-sectional and longitudinal analysis of participants in the Cure Glomerulonephropathy cohort. Preterm (<37 weeks' gestation) was compared with term (≥37 weeks' gestation). A survival analysis and adjusted Cox proportional hazards model were used to examine a composite outcome of 40% decline in eGFR or progression to kidney failure. An adjusted logistic regression model was used to examine remission of proteinuria.

Results

There were 2205 term and 235 preterm participants. Apolipoprotein L1 (APOL1 ) risk alleles were more common in those born preterm. More pediatric than adult participants in Cure Glomerulonephropathy were born preterm: 12.8% versus 7.69% (P < 0.001). Adults born preterm compared with term had a higher prevalence of FSGS (35% versus 25%, P = 0.01) and APOL1 high-risk genotype (9.4% versus 4.2%, P = 0.01). Participants born preterm had a shorter time interval to a 40% eGFR decline/kidney failure after biopsy (P = 0.001). In adjusted analysis, preterm participants were 28% more likely to develop 40% eGFR decline/kidney failure (hazard ratio: 1.28 [1.07 to 1.54], P = 0.008) and 38% less likely to attain complete remission of proteinuria (odds ratio: 0.62 [0.45 to 0.87], P = 0.006). There was no significant difference in cardiovascular events.

Conclusions

Preterm birth was a risk factor for adverse outcomes in this heterogeneous cohort of children and adults with glomerular disease. Adults born preterm were more likely to have an APOL1 high-risk genotype and FSGS. In analyses adjusted for FSGS and APOL1 risk status, there was less remission and faster progression of kidney disease in those born preterm.

Elevated Exposure to Air Pollutants Accelerates Primary Glomerular Disease Progression

Introduction

Environmental contributors to kidney disease progression remain elusive. We explored how residential air pollution affects disease progression in patients with primary glomerulopathies.

Methods

Nephrotic Syndrome Study Network (NEPTUNE) and CureGlomerulonephropathy (CureGN) participants with residential census tract data and ≥2 years of follow-up were included. Using Cox proportional hazards models, the associations per doubling in annual average baseline concentrations of total particulate matter with diameter ≤2.5 μm (PM2.5) and its components, black carbon (BC), and sulfate, with time to ≥40% decline in estimated glomerular filtration rate (eGFR) or kidney failure were estimated. Serum tumour necrosis factor levels and kidney tissue transcriptomic inflammatory pathway activation scores were used as molecular markers of disease progression.

Results

PM2.5, BC, and sulfate exposures were comparable in NEPTUNE (n = 228) and CureGN (n = 697). In both cohorts, participants from areas with higher levels of pollutants had lower eGFR, were older and more likely self-reported racial and ethnic minorities. In a fully adjusted model combining both cohorts, kidney disease progression was associated with PM2.5 (adjusted hazard ratio 1.55 [95% confidence interval: 1.00-2.38], P = 0.0489) and BC (adjusted hazard ratio 1.43 [95% confidence interval: 0.98-2.07], P = 0.0608) exposure. Sulfate and PM2.5 exposure were positively correlated with serum tumour necrosis factor (TNF) (P = 0.003) and interleukin-1β levels (P = 0.03), respectively. Sulfate exposure was also directly associated with transcriptional activation of the TNF and JAK-STAT signaling pathways in kidneys (r = 0.55-0.67, P-value <0.01).

Conclusion

Elevated exposure to select air pollutants is associated with increased risk of disease progression and systemic inflammation in patients with primary.

Integrated multi-omics with machine learning to uncover the intricacies of kidney disease

The development of omics technologies has driven a profound expansion in the scale of biological data and the increased complexity in internal dimensions, prompting the utilization of machine learning (ML) as a powerful toolkit for extracting knowledge and understanding underlying biological patterns. Kidney disease represents one of the major growing global health threats with intricate pathogenic mechanisms and a lack of precise molecular pathology-based therapeutic modalities. Accordingly, there is a need for advanced high-throughput approaches to capture implicit molecular features and complement current experiments and statistics. This review aims to delineate strategies for integrating multi-omics data with appropriate ML methods, highlighting key clinical translational scenarios, including predicting disease progression risks to improve medical decision-making, comprehensively understanding disease molecular mechanisms, and practical applications of image recognition in renal digital pathology. Examining the benefits and challenges of current integration efforts is expected to shed light on the complexity of kidney disease and advance clinical practice.

Focal Segmental Glomerulosclerosis

Focal segmental glomerular sclerosis (FSGS) is a histological lesion characterized by sclerosis in sections (segmental) of some glomeruli (focal) in association with podocyte injury. Historically, FSGS has often been characterized as a disease, but it is a heterogeneous entity based on etiology, clinical course, and therapeutic approach. A unifying feature is podocyte injury and loss, which can be primary or the result of secondary maladaptive responses to glomerular stressors. FSGS has been demonstrated over time to carry a large health burden and remains a leading glomerular cause of ESRD globally. Recent clinical practice guidelines highlight the unmet scientific need for better understanding of disease pathogenesis, particularly for immunologic etiologies, as well as more targeted therapeutic drug development. In this review, we will discuss the current FSGS classification scheme, pathophysiologic mechanisms of injury, and treatment guidelines, along with emerging and investigational therapeutics.

PatchSorter: a high throughput deep learning digital pathology tool for object labeling

The discovery of patterns associated with diagnosis, prognosis, and therapy response in digital pathology images often requires intractable labeling of large quantities of histological objects. Here we release an open-source labeling tool, PatchSorter, which integrates deep learning with an intuitive web interface. Using >100,000 objects, we demonstrate a >7x improvement in labels per second over unaided labeling, with minimal impact on labeling accuracy, thus enabling high-throughput labeling of large datasets.

Precision Medicine in Nephrology: An Integrative Framework of Multidimensional Data in the Kidney Precision Medicine Project

Chronic kidney disease (CKD) and acute kidney injury (AKI) are heterogeneous syndromes defined clinically by serial measures of kidney function. Each condition possesses strong histopathologic associations, including glomerular obsolescence or acute tubular necrosis, respectively. Despite such characterization, there remains wide variation in patient outcomes and treatment responses. Precision medicine efforts, as exemplified by the Kidney Precision Medicine Project (KPMP), have begun to establish evolving, spatially anchored, cellular and molecular atlases of the cell types, states, and niches of the kidney in health and disease. The KPMP atlas provides molecular context for CKD and AKI disease drivers and will help define subtypes of disease that are not readily apparent from canonical functional or histopathologic characterization but instead are appreciable through advanced clinical phenotyping, pathomic, transcriptomic, proteomic, epigenomic, and metabolomic interrogation of kidney biopsy samples. This perspective outlines the structure of the KPMP, its approach to the integration of these diverse datasets, and its major outputs relevant to future patient care.

The Significance of Hematuria in Podocytopathies

BACKGROUND

Hematuria is frequently present in podocytopathies, but its significance and prognostic value is not well described in these proteinuric kidney diseases. This study describes the prevalence and association between hematuria and kidney-related outcomes in these disorders.

METHODS

Hematuria was assessed at the initial urinalysis in participants with the following podocytopathies-membranous nephropathy, minimal change disease, and FSGS-in the Nephrotic Syndrome Study Network and Cure Glomerulonephropathy cohorts with >24 months of follow-up. Multivariable Cox proportional hazards models were fit for time to composite outcome (kidney failure or 40% decline in eGFR and eGFR <60 ml/min per 1.73 m 2 ) and proteinuria remission (urine protein-to-creatinine ratio [UPCR] <0.3 mg/mg).

RESULTS

Among the 1516 adults and children in the study, 528 participants (35%) had FSGS, 499 (33%) had minimal change disease, and 489 (32%) had membranous nephropathy. Median (interquartile range) time from biopsy until the initial study urinalysis was 260 (49-750) days, and 498 participants (33%) were positive for hematuria. Participants with hematuria compared with those without were older (37 [16-55] versus 33 [12-55] years), more likely to have an underlying diagnosis of membranous nephropathy (44% versus 27%), had shorter time since biopsy (139 [27-477] versus 325 [89-878] days), and had higher UPCR (3.8 [1.4-8.0] versus 0.9 [0.1-3.1] g/g). After adjusting for diagnosis, age, sex, UPCR, eGFR, time since biopsy, and study cohort, hematuria was associated with a higher risk of reaching the composite outcome (hazard ratio, 1.31; 95% confidence interval, 1.04 to 1.65; P value, 0.02) and lower rate of reaching proteinuria remission (hazard ratio, 0.80; 95% confidence interval, 0.65 to 0.98; P value, 0.03).

CONCLUSIONS

Hematuria is prevalent among participants with the three podocytopathies and is significantly and independently associated with worse kidney-related outcomes, including both progressive loss of kidney function and remission of proteinuria.

Association of COVID-19 Versus COVID-19 Vaccination With Kidney Function and Disease Activity in Primary Glomerular Disease: A Report of the Cure Glomerulonephropathy Study

RATIONALE & OBJECTIVE

Patients with glomerular disease (GN) may be at increased risk of severe COVID-19, yet concerns over vaccines causing disease relapse may lead to vaccine hesitancy. We examined the associations of COVID-19 with longitudinal kidney function and proteinuria and compared these with similar associations with COVID-19 vaccination.

STUDY DESIGN

Observational cohort study from July 1, 2021, to January 1, 2023.

SETTING & PARTICIPANTS

A prospective observational study network of 71 centers from North America and Europe (CureGN) with children and adults with primary minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, or IgA nephropathy.

EXPOSURE

COVID-19 and COVID-19 vaccination.

OUTCOME

Repeated measure of estimated glomerular filtration rate (eGFR); recurrent time-to-event outcome of GN disease worsening as defined by doubling of the urinary protein-creatinine ratio (UPCR) to at least 1.5g/g or increase in dipstick urine protein by 2 ordinal levels to 3+(300mg/dL) or above.

ANALYTICAL APPROACH

Interrupted time series analysis for eGFR. Prognostic matched sequential stratification recurrent event analysis for GN disease worsening.

RESULTS

Among 2,055 participants, 722 (35%) reported COVID-19 infection; of these, 92 (13%) were hospitalized, and 3 died (<1%). The eGFR slope before COVID-19 infection was-1.40mL/min/1.73m2 (± 0.29 SD); within 6 months after COVID-19 infection, the eGFR slope was-4.26mL/min/1.73m2 (± 3.02 SD), which was not significantly different (P=0.34). COVID-19 was associated with increased risk of worsening GN disease activity (HR, 1.35 [95% CI, 1.01-1.80]). Vaccination was not associated with a change in eGFR (-1.34mL/min/1.73m2±0.15 SD vs-2.16mL/min/1.73m2±1.74 SD; P=0.6) or subsequent GN disease worsening (HR 1.02 [95% CI, 0.79-1.33]) in this cohort.

LIMITATIONS

Infrequent or short follow-up.

CONCLUSIONS

Among patients with primary GN, COVID-19 infection was severe for 1 in 8 cases and was associated with subsequent worsening of GN disease activity, as defined by proteinuria. By contrast, vaccination against COVID-19 was not associated with change in disease activity or kidney function decline. These results support COVID-19 vaccination for patients with GN.

PLAIN-LANGUAGE SUMMARY

In this cohort study of 2,055 patients with minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, or IgA nephropathy, COVID-19 resulted in hospitalization or death for 1 in 8 cases and was associated with a 35% increase in risk for worsening proteinuria. By contrast, vaccination did not appear to adversely affect kidney function or proteinuria. Our data support vaccination for COVID-19 in patients with glomerular disease.

Evaluation of Biomarker-Based Glomerular Filtration Rate Estimating Equations in Glomerular Disease

Introduction

Glomerular filtration rate (GFR) is typically estimated with equations that use biomarkers such as serum creatinine and/or cystatin-C. The impact of these different biomarkers on GFR estimates in glomerular disease patients is unclear. In this study, we compared the different GFR estimating equations in the Cure Glomerulonephropathy (CureGN) cohort of children and adults with glomerular disease.

Methods

All available cystatin-C measurements from CureGN study participants were matched to same-day serum creatinine measurements to estimate GFR. To explore the strength of agreement between eGFR values obtained from the "Under 25" (U25) and Chronic Kidney Disease Epidemiology Collaboration (CKD-Epi) equations, we used intraclass correlation coefficients. Multivariable linear mixed effects models were used to determine which factors were independently associated with differences in eGFR values.

Results

A total of 928 cystatin-C measurements were matched to same-day serum creatinine measurements from N = 332 CureGN study participants (58% male, 69% White/Caucasian, 20% Black/African American). Among 628 measurements collected while study participants were under 25 years old, there was moderate agreement (0.731) in serum creatinine versus cystatin-C U25 equations. Models showed that higher eGFR values were associated with larger differences between the two equations (p < 0.001). Among 253 measurements collected while study participants were at least 18 years old, there was excellent agreement (0.891-0.978) among CKD-Epi equations using serum creatinine alone, cystatin-C alone, or the combination of both. Younger age was associated with larger differences between CKD-Epi equations (p = 0.06 to p = 0.016).

Conclusion

Excellent agreement between CKD-Epi equations indicates continued use of serum creatinine alone for GFR estimation could be appropriate for adults. In contrast, only moderate agreement between U25 equations indicates a need for more frequent measurement of cystatin-C among children and young adults, especially as eGFR increases.

Optimal Conservative Therapy Use among Adult Cure Glomerulonephropathy Participants with IgA Nephropathy

Optimal supportive therapy with BP and proteinuria control is pivotal in treating patients with IgA nephropathy. Suboptimal treatment of hypertension and proteinuria persisted in many patients with IgA nephropathy in the Cure Glomerulonephropathy Network study. Many patients had above-target proteinuria despite optimal BP control and may benefit from novel therapies or clinical trials.

The first randomized controlled trial in pediatric nephrology: the history of the International Study of Kidney Disease in Children (ISKDC)

The International Study of Kidney Disease in Children (ISKDC), begun in 1966, conducted the first international collaborative randomized blinded controlled trial in pediatric nephrology and one of the first in either pediatrics or nephrology. For this trial, the ISKDC developed the criteria, such as those for response and relapse, used today to describe the clinical course of the nephrotic syndrome, and the trial generated the nephropathologic terminology and criteria which largely remain the current standards. Over an approximately 20-year span, the ISKDC followed the natural history and evaluated the therapeutic effectiveness of therapies in over 500 children with the nephrotic syndrome from three continents. It published 14 peer-reviewed studies and several reports and commentaries, many of which helped create current standards of practice for therapy of childhood nephrotic syndrome and consequently remain highly cited today. The ISKDC continues to be an important model for subsequent collaborative studies and was the impetus for the development of regional and national pediatric nephrology societies leading to the recognition and growth of pediatric nephrology as a separate subspecialty. A higher resolution version of the Graphical abstract is available as Supplementary information.

Impact of Diabetic Lesions on Pathology, Treatment, and Outcomes of Glomerular Diseases

Key Points

People with glomerular disease (GD) and comorbid diabetes have similar baseline characteristics irrespective of superimposed diabetic lesions. Immunosuppression for GD with comorbid diabetes is the same regardless of superimposed diabetic glomerular lesions. ESKD or death is more rapid in GD and comorbid diabetes only in the presence of moderate-severe diabetic glomerular lesions.

Background

We aimed to evaluate whether concomitant diabetic glomerulosclerosis (DGS) and its severity affect the treatment and outcomes of primary glomerular diseases (GDs) with comorbid diabetes.

Methods

We conducted a retrospective review of people with diabetes and GD. We searched the GD Collaborative Network for biopsies from 2008 to 2015 among persons with diabetes and any of the following diagnoses: FSGS, IgA nephropathy, minimal change disease, membranous nephropathy, or antineutrophil cytoplasmic autoantibody GN. Data were abstracted from health records and histologic diabetic glomerular class scored. The primary composite end point was ESKD or death. Multivariable Cox regression models tested whether any or the severity of diabetes histopathology affected the primary end point.

Results

Data from 134 cases were available for analysis (78 DGS+GD and 56 GD alone). Diabetes duration and glycemic control were similar between the two groups (P = 0.2; P = 0.09, respectively). Use of immunosuppression did not differ between the two groups (P = 0.3). The composite end point was significantly higher in DGS+GD (22.5 cases per 100 person-years [95% confidence interval (CI), 16.6 to 30.5]) versus GD alone (10.2 cases per 100 person-years [95% CI, 6.4 to 16.2]). Regression analyses demonstrated that compared with the GD-alone group, the risk for the composite end point was similar in the group with mild DGS+GD (DGS class 1, 2a) (hazard ratio, 1.15 [95% CI, 0.54 to 2.43]) while the group with severe DGS+GD (DGS class 2b, 3, 4) had a greater risk (hazard ratio, 3.60 [1.79 to 7.22]).

Conclusions

Among people with diabetes and GD, mild diabetic glomerular lesions on biopsy do not affect outcomes, but moderate-severe lesions increase the risk for ESKD and death. Whether use of immunosuppression, particularly glucocorticoids, is less successful in inducing GD remission in people with moderate-severe diabetic lesions will be a focus of future study in a larger population.

Indian TrANslational GlomerulonephrItis BioLogy nEtwork (I-TANGIBLE): Design and Methods

Background and Aim

Primary glomerular disease accounts for one-sixth of all chronic kidney diseases (CKDs) in India. We remain limited in our ability to effectively treat these conditions because of lack of understanding of the disease mechanisms and lack of predictors to identify the clinical course and therapeutic responsiveness. We propose to develop a network of investigators in glomerular diseases, collect information in a systematic fashion to understand the clinical outcomes, answer translational research questions better, and identify and recruit patients for clinical trials.

Materials and Methods

This is a prospective, observational study. The Indian TrANslational GlomerulonephrItis BioLogy nEtwork (I-TANGIBLE) cohort will enroll patients (>18 years) with biopsy-proven minimal change disease (MCD), focal segmental glomerulonephritis (FSGS), membranous nephropathy (MN), IgA nephropathy (IgAN), or membranoproliferative glomerulonephritis (MPGN) (immune complex- and complement-mediated), with first biopsy taken within 2 years of enrollment. Patients with estimated glomerular filtration (eGFR) rate <15 ml/min/1.73 m2 for >3 months at the time of screening, kidney transplant or bone marrow transplant recipients, patients with active malignancy, and patients with active hepatitis B/C replication or human immunodeficiency virus (HIV)-I/II will be excluded. Clinical details including history, medication history and details, and family history will be obtained. Consenting patient's blood and urine samples will be collected and stored, aligned to their clinical follow-up.

Expected Outcomes

The network will allow accurate ascertainment of disease burden of glomerular diseases across study sites, establishment of the treatment pattern of common glomerular diseases, investigation of medium- and long-term outcomes (remission, relapse, rate of eGFR decline), and building a suitable infrastructure to carry out clinical trials in primary glomerular disease.

Multiomics Analysis of Plasma Proteomics and Metabolomics of Steroid Resistance in Childhood Nephrotic Syndrome Using a "Patient-Specific" Approach

Introduction

Nephrotic syndrome (NS) occurs commonly in children with glomerular disease and glucocorticoids (GCs) are the mainstay treatment. Steroid resistant NS (SRNS) develops in 15% to 20% of children, increasing the risk of chronic kidney disease compared to steroid sensitive NS (SSNS). NS pathogenesis is unclear in most children, and no biomarkers exist that predict the development of pediatric SRNS.

Methods

We studied a unique patient cohort with plasma specimens collected before GC treatment, yielding a disease-only sample not confounded by steroid-induced gene expression changes (SSNS n = 8; SRNS n = 7). A novel "patient-specific" bioinformatic approach merged paired pretreatment and posttreatment proteomic and metabolomic data and identified candidate SRNS biomarkers and altered molecular pathways in SRNS versus SSNS.

Results

Joint pathway analyses revealed perturbations in nicotinate or nicotinamide and butanoate metabolic pathways in patients with SRNS. Patients with SSNS had perturbations of lysine degradation, mucin type O-glycan biosynthesis, and glycolysis or gluconeogenesis pathways. Molecular analyses revealed frequent alteration of molecules within these pathways that had not been observed by separate proteomic and metabolomic studies. We observed upregulation of NAMPT, NMNAT1, and SETMAR in patients with SRNS, in contrast to upregulation of ALDH1B1, ACAT1, AASS, ENPP1, and pyruvate in patients with SSNS. Pyruvate regulation was the change seen in our previous analysis; all other targets were novel. Immunoblotting confirmed increased NAMPT expression in SRNS and increased ALDH1B1 and ACAT1 expression in SSNS, following GC treatment.

Conclusion

These studies confirmed that a novel "patient-specific" bioinformatic approach can integrate disparate omics datasets and identify candidate SRNS biomarkers not observed by separate proteomic or metabolomic analysis.

Age of Onset and Disease Course in Biopsy-Proven Minimal Change Disease: An Analysis From the Cure Glomerulonephropathy Network

RATIONALE & OBJECTIVE

Adolescent- and adult-onset minimal change disease (MCD) may have a clinical course distinct from childhood-onset disease. We characterized the course of children and adults with MCD in the Cure Glomerulonephropathy Network (CureGN) and assessed predictors of rituximab response.

STUDY DESIGN

Prospective, multicenter, observational study.

STUDY PARTICIPANTS

CureGN participants with proven MCD on biopsy.

EXPOSURE

Age at disease onset, initiation of renin-angiotensin-aldosterone system (RAAS) blockade, and immunosuppression including rituximab during the study period.

OUTCOME

Relapse and remission, change in estimated glomerular filtration rate (eGFR), and kidney failure.

ANALYTICAL APPROACH

Remission and relapse probabilities were estimated using Kaplan-Meier curves and gap time recurrent event models. Linear regression models were used for the outcome of change in eGFR. Cox proportional hazards models were used to estimate the association between rituximab administration and remission.

RESULTS

The study included 304 childhood- (≤12 years old), 49 adolescent- (13-17 years old), and 201 adult- (≥18 years) onset participants with 2.7-3.2 years of follow-up after enrollment. Children had a longer time to biopsy (238 vs 23 and 36 days in adolescent- and adult-onset participants, respectively; P<0.001) and were more likely to have received therapy before biopsy. Children were more likely to be treated with immunosuppression but not RAAS blockade. The rate of relapse was higher in childhood- versus adult-onset participants (HR, 1.69 [95% CI, 1.29-2.21]). The probability of remission was also higher in childhood-onset disease (HR, 1.33 [95%CI, 1.02-1.72]). In all groups eGFR loss was minimal. Children were more likely to remit after rituximab than those with adolescent- or adult-onset disease (adjusted HR, 2.1; P=0.003). Across all groups, glucocorticoid sensitivity was associated with a greater likelihood of achieving complete remission after rituximab (adjusted HR, 2.62; P=0.002).

LIMITATIONS

CureGN was limited to biopsy-proven disease. Comparisons of childhood to nonchildhood cases of MCD may be subject to selection bias, given that childhood cases who undergo a biopsy may be limited to patients who are least responsive to initial therapy.

CONCLUSIONS

Among patients with MCD who underwent kidney biopsy, there were differences in the course (relapse and remission) of childhood-onset compared with adolescent- and adult-onset disease, as well as rituximab response.

PLAIN-LANGUAGE SUMMARY

Minimal change disease is a biopsy diagnosis for nephrotic syndrome. It is diagnosed in childhood, adolescence, or adulthood. Patients and clinicians often have questions about what to expect in the disease course and how to plan therapies. We analyzed a group of patients followed longitudinally as part of the Cure Glomerulonephropathy Network (CureGN) and describe the differences in disease (relapse and remission) based on the age of onset. We also analyzed rituximab response. We found that those with childhood-onset disease had a higher rate of relapse but also have a higher probability of reaching remission when compared with adolescent- or adult-onset disease. Children and all steroid-responsive patients are more likely to achieve remission after rituximab.

Rapid Progression of Focal Segmental Glomerulosclerosis in Patients with High-Risk APOL1 Genotypes

BACKGROUND

FSGS is a heterogeneous diagnosis with a guarded prognosis. Polymorphisms in the apolipoprotein L1 ( APOL1 ) gene are associated with developing FSGS and faster progression to kidney failure in affected patients. Better understanding the natural history of patients with FSGS and APOL1 risk alleles is essential to improve patient care and support the design and interpretation of interventional studies. The objective of this study was to evaluate the quantitative association between APOL1 and kidney disease progression and the interaction with other clinical and laboratory factors.

METHODS

CureGN cohort study participants with biopsy diagnosis of FSGS, regardless of self-identified race, were included. The exposure of interest was two APOL1 risk alleles (high risk) versus zero to one risk alleles (low risk). The primary outcome was eGFR slope categorized as rapid progressor (eGFR slope ≤-5 ml/min per year), intermediate progressor (slope between 0 and -5), or nonprogressor (slope ≥0). Multivariable ordinal logistic and linear regressions were used for adjusted analyses. Missing data were addressed using multiple imputation.

RESULTS

Of 650 participants, 476 (73%) had genetic testing, among whom 87 (18%) were high risk. High-risk participants were more likely to have lower median eGFR (62 [interquartile range, 36-81] versus low-risk participants 76 ml/min per 1.73 m 2 [interquartile range, 44-106]; P <0.01). In adjusted analysis, the odds of more rapid progression of eGFR was 2.75 times higher (95% confidence interval, 1.67 to 4.53; P <0.001) in the high-risk versus low-risk groups.

CONCLUSIONS

In patients with FSGS, high-risk APOL1 genotype is the predominant factor associated with more rapid loss of kidney function.

Racial and Ethnic Disparities in Acute Care Utilization Among Patients With Glomerular Disease

RATIONALE & OBJECTIVE

The effects of race, ethnicity, socioeconomic status (SES), and disease severity on acute care utilization in patients with glomerular disease are unknown.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

1,456 adults and 768 children with biopsy-proven glomerular disease enrolled in the Cure Glomerulonephropathy (CureGN) cohort.

EXPOSURE

Race and ethnicity as a participant-reported social factor.

OUTCOME

Acute care utilization defined as hospitalizations or emergency department visits.

ANALYTICAL APPROACH

Multivariable recurrent event proportional rate models were used to estimate associations between race and ethnicity and acute care utilization.

RESULTS

Black or Hispanic participants had lower SES and more severe glomerular disease than White or Asian participants. Acute care utilization rates were 45.6, 29.5, 25.8, and 19.2 per 100 person-years in Black, Hispanic, White, and Asian adults, respectively, and 55.8, 42.5, 40.8, and 13.0, respectively, for children. Compared with the White race (reference group), Black race was significantly associated with acute care utilization in adults (rate ratio [RR], 1.76 [95% CI, 1.37-2.27]), although this finding was attenuated after multivariable adjustment (RR, 1.31 [95% CI, 1.03-1.68]). Black race was not significantly associated with acute care utilization in children; Asian race was significantly associated with lower acute care utilization in children (RR, 0.32 [95% CI 0.14-0.70]); no significant associations between Hispanic ethnicity and acute care utilization were identified.

LIMITATIONS

We used proxies for SES and lacked direct information on income, household unemployment, or disability.

CONCLUSIONS

Significant differences in acute care utilization rates were observed across racial and ethnic groups in persons with prevalent glomerular disease, although many of these difference were explained by differences in SES and disease severity. Measures to combat socioeconomic disadvantage in Black patients and to more effectively prevent and treat glomerular disease are needed to reduce disparities in acute care utilization, improve patient wellbeing, and reduce health care costs.

Kidney Disease Progression in Membranous Nephropathy among Black Participants with High-Risk APOL1 Genotype

BACKGROUND

Disparity in CKD progression among Black individuals persists in glomerular diseases. Genetic variants in the apolipoprotein L1 ( APOL1 ) gene in the Black population contribute to kidney disease, but the influence in membranous nephropathy remains unknown.

METHODS

Longitudinally followed participants enrolled in the Glomerular Disease Collaborative Network or Cure Glomerulonephropathy Network were included if they had DNA or genotyping available for APOL1 (Black participants with membranous nephropathy) or had membranous nephropathy but were not Black. eGFR slopes were estimated using linear mixed-effects models with random effects and adjusting for covariates and interaction terms of covariates. Fisher exact test, Kruskal-Wallis test, and Kaplan-Meier curves with log-rank tests were used to compare groups.

RESULTS

Among 118 Black membranous nephropathy participants, 16 (14%) had high-risk APOL1 genotype (two risk alleles) and 102 (86%) had low-risk APOL1 genotype (zero or one risk alleles, n =53 and n =49, respectively). High-risk APOL1 membranous nephropathy participants were notably younger at disease onset than low-risk APOL1 and membranous nephropathy participants that were not Black ( n =572). eGFR at disease onset was not different between groups, although eGFR decline (slope) was steeper in participants with high-risk APOL1 genotype (-16±2 [±SE] ml/min per 1.73 m 2 per year) compared with low-risk APOL1 genotype (-4±0.8 ml/min per 1.73 m 2 per year) or membranous nephropathy participants that did not identify themselves as Black (-2.0±0.4 ml/min per 1.73 m 2 per year) ( P <0.0001). Time to kidney failure was faster in the high-risk APOL1 genotype than low-risk APOL1 genotype or membranous nephropathy participants that were not Black.

CONCLUSIONS

The prevalence of high-risk APOL1 variant among Black membranous nephropathy participants is comparable with the general Black population (10%-15%), yet the high-risk genotype was associated with worse eGFR decline and faster time to kidney failure compared with low-risk genotype and participants that were not Black.

Pregnancy History and Kidney Disease Progression Among Women Enrolled in Cure Glomerulonephropathy

Introduction

Preeclampsia increases the risk for future chronic kidney disease (CKD). Among those diagnosed with CKD, it is unclear whether a prior history of preeclampsia, or other complications in pregnancy, negatively impact kidney disease progression. In this longitudinal analysis, we assessed kidney disease progression among women with glomerular disease with and without a history of a complicated pregnancy.

Methods

Adult women enrolled in the Cure Glomerulonephropathy study (CureGN) were classified based on a history of a complicated pregnancy (defined by presence of worsening kidney function, proteinuria, or blood pressure; or a diagnosis of preeclampsia, eclampsia, or hemolysis, elevated liver enzymes, and low platelets [HELLP] syndrome), pregnancy without these complications, or no pregnancy history at CureGN enrollment. Linear mixed models were used to assess estimated glomerular filtration rate (eGFR) trajectories and urine protein-to-creatinine ratios (UPCRs) from enrollment.

Results

Over a median follow-up period of 36 months, the adjusted decline in eGFR was greater in women with a history of a complicated pregnancy compared to those with uncomplicated or no pregnancies (-1.96 [-2.67, -1.26] vs. -0.80 [-1.19, -0.42] and -0.64 [-1.17, -0.11] ml/min per 1.73 m² per year, P = 0.007). Proteinuria did not differ significantly over time. Among those with a complicated pregnancy history, eGFR slope did not differ by timing of first complicated pregnancy relative to glomerular disease diagnosis.

Conclusions

A history of complicated pregnancy was associated with greater eGFR decline in the years following glomerulonephropathy (GN) diagnosis. A detailed obstetric history may inform counseling regarding disease progression in women with glomerular disease. Continued research is necessary to better understand pathophysiologic mechanisms by which complicated pregnancies contribute to glomerular disease progression.

CureGN-Diabetes Study: Rationale, Design, and Methods of a Prospective Observational Study of Glomerular Disease Patients with Diabetes

Glomerular diseases (GDs) represent the third leading cause of end-stage kidney disease (ESKD) in the US Diabetes was excluded from the CureGN Study, an NIH/NIDDK-sponsored observational cohort study of four leading primary GDs: IgA nephropathy (IgAN), membranous nephropathy (MN), focal segmental glomerulosclerosis (FSGS), and minimal change disease (MCD). CureGN-Diabetes, an ancillary study to CureGN, seeks to understand how diabetes influences the diagnosis, treatment, and outcomes of GD. It is a multicenter, prospective cohort study, targeting an enrollment of 300 adults with prevalent type 1 or type 2 diabetes and MCD, FSGS, MN, or IgAN, with first kidney biopsy obtained within 5 years of enrollment in 80% (20% allowed if biopsy after 2010). CureGN and Transformative Research in DiabEtic NephropaThy (TRIDENT) provide comparator cohorts. Retrospective and prospective clinical data and patient-reported outcomes are obtained. Blood and urine specimens are collected at study visits annually. Kidney biopsy reports and digital images are obtained, and standardized pathologic evaluations performed. Light microscopy images are uploaded to the NIH pathology repository. Outcomes include relapse and remission rates, changes in proteinuria and estimated glomerular filtration rate, infections, cardiovascular events, malignancy, ESKD, and death. Multiple analytical approaches will be used leveraging the baseline and longitudinal data to compare disease presentation and progression across subgroups of interest. With 300 patients and an average of 3 years of follow-up, the study has 80% power to detect a HR of 1.4-1.8 for time to complete remission of proteinuria, a rate ratio for hospitalizations of 1.18-1.56 and difference in eGFR slope of 6.0-8.6 mL/min/year between two groups of 300 participants each. CureGN-Diabetes will enhance our understanding of diabetes as a modifying factor of the pathology and outcomes of GDs and support studies to identify disease mechanisms and improve patient outcomes in this understudied patient population.

Cure Glomerulonephropathy Pathology Classification and Core Scoring Criteria, Reproducibility, and Clinicopathologic Correlations

Introduction

Cure Glomerulonephropathy (CureGN) is an observational cohort study of patients with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), or IgA nephropathy. We developed a conventional, consensus-based scoring system to document pathologic features for application across multiple pathologists and herein describe the protocol, reproducibility, and correlation with clinical parameters at biopsy.

Methods

Definitions were established for glomerular, tubular, interstitial, and vascular lesions evaluated semiquantitatively using digitized light microscopy slides and electron micrographs, and reported immunofluorescence. Cases with curated pathology materials as of April 2019 were scored by a randomly assigned pathologist, with at least 10% of cases scored by a second pathologist. Scoring reproducibility was assessed using Gwet's agreement coefficient (AC)1 statistic and correlations with clinical variables were performed.

Results

Of 800 scored biopsies (134 MCD, 194 FSGS, 206 MN, 266 IgA), 94 were scored twice (11.8%). Of 60 pathology features, 46 (76.7%) demonstrated excellent (AC1>0.8), and 12 (20.0%) had good (AC1 0.6-0.8) reproducibility. Mesangial hypercellularity scored as absent, focal, or diffuse had moderate reproducibility (AC1 = 0.58), but good reproducibility (AC1 = 0.71) when scored as absent or focal versus diffuse. The percent glomeruli scored as no lesions had fair reproducibility (AC1 = 0.34). Strongest correlations between pathologic features and clinical characteristics at biopsy included interstitial inflammation, interstitial fibrosis, and tubular atrophy with estimated glomerular filtration rate, foot process effacement with urine protein/creatinine ratio, and active crescents with hematuria.

Conclusions

Most scored pathology features showed excellent reproducibility, demonstrating consistency for these features across multiple pathologists. Correlations between certain pathologic features and expected clinical characteristics show the value of this approach for future studies on clinicopathologic correlations and biomarker discovery.

Present and future directions in diabetic kidney disease

Diabetic kidney disease (DKD) is the leading cause of kidney failure and is associated with substantial risk of cardiovascular disease, morbidity, and mortality. Traditionally, DKD prevention and management have focused on addressing hyperglycemia, hypertension, obesity, and renin-angiotensin system activation as important risk factors for disease. Over the last decade, sodium-glucose cotransporter-2 inhibitors and glucagon-like peptide-1 receptor agonists have been shown to meaningfully reduce risk of diabetes-related kidney and cardiovascular complications. Additional agents demonstrating benefit in DKD such as non-steroidal mineralocorticoid receptor antagonists and endothelin A receptor antagonists are further contributing to the growing arsenal of DKD therapies. With the availability of greater therapeutic options comes the opportunity to individually optimize DKD prevention and management. Novel applications of transcriptomic, proteomic, and metabolomic/lipidomic technologies, as well as use of artificial intelligence and reinforced learning methods through consortia such as the Kidney Precision Medicine Project and focused studies in established cohorts hold tremendous promise for advancing our understanding and treatment of DKD. Specifically, enhanced understanding of the molecular mechanisms underlying DKD pathophysiology may allow for the identification of new mechanism-based DKD subtypes and the development and implementation of targeted therapies. Implementation of personalized care approaches has the potential to revolutionize DKD care.

Immunosuppression Exposure and Risk of Infection-Related Acute Care Events in Patients With Glomerular Disease: An Observational Cohort Study

Rationale & Objective

Infections cause morbidity and mortality in patients with glomerular disease. The relative contributions from immunosuppression exposure and glomerular disease activity to infection risk are not well characterized. To address this unmet need, we characterized the relationship between time-varying combinations of immunosuppressant exposure and infection-related acute care events while controlling for disease activity, among individuals with glomerular disease.

Study Design

Prospective, multicenter, observational cohort study.

Setting & Participants

Adults and children with biopsy-proven minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, or immunoglobulin A nephropathy/vasculitis were enrolled at 71 clinical sites in North America and Europe. A total of 2,388 Cure Glomerulonephropathy Network participants (36% aged <18 years) had at least 1 follow-up visit and were included in the analysis.

Exposures

Immunosuppression exposure modeled on a weekly basis.

Outcome

Infections leading to an emergency department visit or hospitalization.

Analytical Approach

Marginal structural models were used to estimate the effect of time-varying immunosuppression exposure on hazard of first infection-related acute care event while accounting for baseline sociodemographic and clinical factors, and time-varying disease activity.

Results

A total of 2,388 participants were followed for a median of 3.2 years (interquartile range, 1.6-4.6), and 15% experienced at least 1 infection-related emergency department visit or hospitalization. Compared to no immunosuppression exposure, steroid exposure, steroid with any other immunosuppressant, and nonsteroid immunosuppressant exposure were associated with a 2.65-fold (95% CI, 1.83-3.86), 2.68-fold (95% CI, 1.95-3.68), and 1.7-fold (95% CI, 1.29-2.24) higher risk of first infection, respectively.

Limitations

Absence of medication dosing data, lack of a control group, and potential bias in ascertainment of outcome events secondary to the coronavirus 2 pandemic.

Conclusions

Corticosteroids with or without concomitant additional immunosuppression significantly increased risk of infection leading to acute care utilization in adults and children with glomerular disease.

Novel Treatment Paradigms: Focal Segmental Glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a histologic pattern of injury defined by the presence of sclerosis in some (segmental) of certain glomeruli (focal). On electron microscopy, it is characterized by a variable degree of podocyte foot process effacement and gaps in the coverage of the glomerular basement membrane. The pattern of injury occurs when podocytes, highly differentiated cells with limited regenerative capacity, are reduced in number. The heterogeneity in underlying causes of podocyte loss results in equally variable clinical phenotypes. Recent work acknowledging advances in defining the genetic and immunologic basis of disease has redefined the classification of FSGS. Unprecedented clinical trial activity and efficacy of repurposed agents presents hope for improved therapeutic options. This minireview summarizes recent advances with a focus on novel treatment paradigms in FSGS.

Clinicopathologic Significance of Predominant Lambda Light Chain Deposition in IgA Nephropathy

Introduction

IgA nephropathy (IgAN) differs from other glomerular diseases by the frequently predominant lambda over kappa light chain deposition. Using the Cure Glomerulonephropathy (CureGN) IgAN cohort, we aimed to determine whether predominant lambda chain deposition is associated with worse clinical outcomes or histopathologic markers of more active disease.

Methods

Patients were categorized based on the intensity of light chain staining. The lambda dominant (LD) group was defined by a difference in intensity score of lambda minus kappa ≥ 1+ and the kappa-lambda codominant (KL) group by a difference < 1+. We compared the clinical course of patients in each category from the time of kidney biopsy and time of enrollment into CureGN to the time of remission (proteinuria < 0.3 g/g), 50% reduction in estimated glomerular filtration rate (eGFR), or progression to end-stage kidney disease (ESKD). We also analyzed differences in histopathologic characteristics between the 2 groups.

Results

Among 440 patients, we found no significant differences between groups in baseline clinical characteristics nor in rates of remission, 50% reduction in eGFR, or progression to ESKD. Patients in the LD group had a modestly greater frequency of IgG staining ≥ 1+. The biopsy results of 234 patients reviewed by CureGN pathologists revealed a greater frequency of endocapillary hypercellularity (51.1% vs. 36.3%, P = 0.04) in the LD group, but no other significant difference in histopathologic features.

Conclusion

In IgAN, we found an association between lambda predominance and increased endocapillary hypercellularity, but no association with clinical outcomes.

Delivery of Active Medical Management without Dialysis through an Embedded Kidney Palliative Care Model

Background

Patients with CKD have high symptom burden, low rates of advance care planning (ACP), and frequently receive care that is not goal concordant. Improved integration of palliative care into nephrology and access to active medical management without dialysis (AMMWD) have the potential to improve outcomes through better symptom management and enhanced shared decision making.

Methods

We describe the development of a kidney palliative care (KPC) clinic and how palliative care practices are integrated within an academic nephrology clinic. We performed a retrospective electronic health record (EHR) review for patients seen in this clinic between January 2015 and February 2019 to describe key clinical activities and delivery of AMMWD.

Results

A total of 165 patients were seen in the KPC clinic (139 with CKD and 26 who were already receiving dialysis). Fatigue, mobility issues, and pain were the three most prevalent symptoms (85%, 66%, 58%, respectively). Ninety-one percent of patients had a surrogate decision maker documented in the EHR; 87% of patients had a goals-of-care conversation documented in the EHR. Of the 139 patients with CKD, 67 (48%) chose AMMWD as their disease progressed. Sixty-eight percent (41 of 60) of patients who died during the study were referred to hospice.

Conclusions

Our findings suggest that the integration of palliative care into nephrology can assist in identification of symptoms, lead to high rates of ACP, and provide a mechanism for patients to choose and receive AMMWD. The percentage of patients choosing AMMWD in our study suggests that increased shared decision making may lower rates of dialysis initiation in the United States. Additional prospective research and registries for assessing the effects of AMMWD have the potential to improve care for people living with CKD.

The Canadian Glomerulonephritis Registry (CGNR) and Translational Research Initiative: Rationale and Clinical Research Protocol

Background

Glomerulonephritis (GN) is a leading cause of kidney failure and accounts for 20% of incident cases of end-stage kidney disease (ESKD) in Canada annually. Reversal of kidney injury and prevention of progression to kidney failure is possible; however, limited knowledge of underlying disease mechanisms and lack of noninvasive biomarkers and therapeutic targets are major barriers to successful therapeutic intervention. Multicenter approaches that link longitudinal clinical and outcomes data with serial biologic specimen collection would help bridge this gap.

Objective

To establish a national, patient-centered, multidimensional web-based clinical database and federated virtual biobank to conduct human-based molecular and clinical research in GN in Canada.

Design

Multicenter, prospective observational registry, starting in 2019.

Setting

Nine participating Canadian tertiary care centers.

Patients

Adult patients with a histopathologic pattern of injury consistent with IgA nephropathy, focal and segmental glomerulosclerosis, minimal change disease, membranous nephropathy, C3 glomerulopathy, and membranoproliferative GN recruited within 24 months of biopsy.

Measurements

Initial visits include detailed clinical, histopathological, and laboratory data collection, blood, urine, and tonsil swab biospecimen collection, and a self-administered quality of life questionnaire. Follow-up clinical and laboratory data collection, biospecimen collection, and questionnaires are obtained every 6 months thereafter.

Methods

Patients receive care as defined by their physician, with study visits scheduled every 6 months. Patients are followed until death, dialysis, transplantation, or withdrawal from the study. Key outcomes include a composite of ESKD or a 40% decline in estimated glomerular filtration rate (eGFR) at 2 years, rate of kidney function decline, and remission of proteinuria. Clinical and molecular phenotypical data will be analyzed by GN subtype to identify disease predictors and discover therapeutic targets.

Limitations

Given the relative rarity of individual glomerular diseases, one of the major challenges is patient recruitment. Initial registry studies may be underpowered to detect small differences in clinically meaningful outcomes such as ESKD or death due to small sample sizes and short duration of follow-up in the initial 2-year phase of the study.

Conclusions

The Canadian Glomerulonephritis Registry (CGNR) supports national collaborative efforts to study glomerular disease patients and their outcomes.

Trial registration

NCT03460054.

IgA vasculitis nephritis

PURPOSE OF REVIEW

The purpose of this update is to summarize current knowledge on the pathophysiology of immunglobulin A (IgA) vasculitis nephritis (IgAVN) as well as to critically review evidence for established therapeutic regimes and available biomarkers. An additional purpose is to raise the discussion what could be done to further improve our understanding of IgAVN, identify patients at risk for adverse outcome and increase the evidence for therapy recommendations.

RECENT FINDINGS

Clinical and experimental studies have established the concept of a multilevel pathogenesis. Toll-like-receptor activation, B cell proliferation, micro-RNAs and complement activation have been identified or confirmed as potential therapeutic targets which can modify the course of the disease. Currently, kidney injury molecule-1, monocyte chemotactic protein-1, N-acetyl-β-glucosaminidase, and angiotensinogen are the most promising urinary biomarkers for early diagnosis of renal involvement in IgA vasculitis.

SUMMARY

Close surveillance of all IgAV patients for renal involvement is recommended. Given the multilevel pathogenesis, early treatment of even mild cases should be initiated. Further therapeutic options should be considered in case first-line therapy (mostly corticosteroids) has no effect. The evidence supporting current therapeutic regimes is predominantly based on expert opinion. Prospective studies are needed and should involve substances inhibiting B cell proliferation and complement activation.

Cellular and molecular interrogation of kidney biopsy specimens

PURPOSE OF REVIEW

Traditional histopathology of the kidney biopsy specimen has been an essential and successful tool for the diagnosis and staging of kidney diseases. However, it is likely that the full potential of the kidney biopsy has not been tapped so far. Indeed, there is now a concerted worldwide effort to interrogate kidney biopsy samples at the cellular and molecular levels with unprecedented rigor and depth. This review examines these novel approaches to study kidney biopsy specimens and highlights their potential to refine our understanding of the pathophysiology of kidney disease and lead to precision-based diagnosis and therapy.

RECENT FINDINGS

Several consortia are now active at studying kidney biopsy samples from various patient cohorts with state-of-the art cellular and molecular techniques. These include advanced imaging approaches as well as deep molecular interrogation with tools such as epigenetics, transcriptomics, proteomics and metabolomics. The emphasis throughout is on rigor, reproducibility and quality control.

SUMMARY

Although these techniques to study kidney biopsies are complementary, each on its own can yield novel ways to define and classify kidney disease. Therefore, great efforts are needed in order to generate an integrated output that can propel the diagnosis and treatment of kidney disease into the realm of precision medicine.

Impact of Consensus Definitions on Identification of Glomerular Lesions by Light and Electron Microscopy

Introduction

In 2020, a working group of 13 renal pathologists published consensus definitions for 47 individual glomerular lesions found on light microscopy (LM) and 47 glomerular lesions and 9 normal structures found on electron microscopy (EM).

Methods

To test the impact of these definitions on identification of these lesions and structures, 2 surveys were circulated to all members of the Renal Pathology Society (RPS), each having 32 images (19 LM, 13 EM) and accompanying questions with 5 multiple-choice answers, one being the consensus choice of the working group. The first survey (survey 1 [S1]), answered by 297 RPS members, was sent in September 2020, before publication of the consensus definitions. The second (survey 2 [S2]), with images of the same lesions and structures (but not the same images) and the same questions and multiple choices in different order, was sent in April 2020, 5 months after the publication of the definitions.

Results

S2 was taken by 181 RPS members; 64% also took S1 and 61% reported having read the definitions paper (def. paper). Mean agreement with the consensus answers increased modestly between the 2 surveys (65.2% vs. 72.0%, P = 0.097); the increase was greater and significant when only respondents to S2 who read the def. paper were considered (65.2% vs. 74.8%, P = 0.026). Furthermore, in S2 agreement with consensus answers was greater among respondents who read this paper versus those who did not (66.9% vs. 74.8%, P < 0.0001).

Conclusions

Publication of the consensus definitions modestly improved interobserver agreement in identification of glomerular lesions.

Precision medicine for the treatment of glomerulonephritis: A bold goal but not yet a transformative achievement

The revolution in our ability to recognize the alterations in fundamental biology brought about by disease has fostered a renewed interest in precision or personalized medicine (“the right treatment, or diagnostic test, for the right patient at the right time”). This nascent field has been led by oncology, immune-hematology and infectious disease, but nephrology is catching up, and quickly. Specific forms of glomerulonephritis thought to represent specific “diseases” have been “downgraded” to “patterns of injury”. New entities have emerged through application of sophisticated molecular technologies; often embraced by the term “multi-omics”. Kidney biopsies are now interpreted by next generation imaging and machine learning. Many opportunities are manifest that will translate these remarkable developments into novel safe and effective treatment regimens for specific pathogenic pathways evoking glomerulonephritis and its progression to kidney failure. A few successes emboldens a positive look to the future. A sustained and highly collaborative engagement with this new paradigm will be required for this field, full of hope and high expectations, to realize its goal of transforming glomerular therapeutics from “one size fits all (or many)” to a true individualized management principle.

Racial-ethnic differences in health-related quality of life among adults and children with glomerular disease

Introduction

Disparities in health-related quality of life (HRQOL) have been inadequately studied in patients with glomerular disease. The aim of this study was to identify relationships between race/ethnicity, socioeconomic status, disease severity, and HRQOL in an ethnically and racially diverse cohort of patients with glomerular disease.

Methods

Cure Glomerulonephropathy (CureGN) is a multinational cohort study of patients with biopsy-proven glomerular disease. Associations between race/ethnicity and HRQOL were determined by the following: 1. Missed school or work due to kidney disease; 2. Responses to Patient Reported Outcomes Measurement Information System (PROMIS) questionnaires. We adjusted for demographics, socioeconomic status, and disease characteristics using multivariable logistic and linear regression.

Results

Black and Hispanic participants had worse socioeconomic status and more severe glomerular disease than White or Asian participants. Black adults missed work or school most frequently due to kidney disease (30% versus 16-23% in the other three groups, p=0.04), and had the worst self-reported global physical health (median score 44.1 versus 48.0-48.2, p<0.001) and fatigue (53.8 versus 48.5-51.1, p=0.002), compared to other racial/ethnic groups. However, these findings were not statistically significant with adjustment for socioeconomic status and disease severity, both of which were strongly associated with HRQOL in adults. Among children, disease severity but not race/ethnicity or socioeconomic status were associated with HRQOL.

Conclusions

Among patients with glomerular disease enrolled in CureGN, the worse HRQOL reported by Black adults was attributable to lower socioeconomic status and more severe glomerular disease. No racial/ethnic differences in HRQOL were observed in children.

Population-based identification and temporal trend of children with primary nephrotic syndrome: The Kaiser Permanente nephrotic syndrome study

INTRODUCTION

Limited population-based data exist about children with primary nephrotic syndrome (NS).

METHODS

We identified a cohort of children with primary NS receiving care in Kaiser Permanente Northern California, an integrated healthcare delivery system caring for >750,000 children. We identified all children <18 years between 1996 and 2012 who had nephrotic range proteinuria (urine ACR>3500 mg/g, urine PCR>3.5 mg/mg, 24-hour urine protein>3500 mg or urine dipstick>300 mg/dL) in laboratory databases or a diagnosis of NS in electronic health records. Nephrologists reviewed health records for clinical presentation and laboratory and biopsy results to confirm primary NS.

RESULTS

Among 365 cases of confirmed NS, 179 had confirmed primary NS attributed to presumed minimal change disease (MCD) (72%), focal segmental glomerulosclerosis (FSGS) (23%) or membranous nephropathy (MN) (5%). The overall incidence of primary NS was 1.47 (95% Confidence Interval:1.27-1.70) per 100,000 person-years. Biopsy data were available in 40% of cases. Median age for patients with primary NS was 6.9 (interquartile range:3.7 to 12.9) years, 43% were female and 26% were white, 13% black, 17% Asian/Pacific Islander, and 32% Hispanic.

CONCLUSION

This population-based identification of children with primary NS leveraging electronic health records can provide a unique approach and platform for describing the natural history of NS and identifying determinants of outcomes in children with primary NS.

Machine Learning Applications in Nephrology: A Bibliometric Analysis Comparing Kidney Studies to Other Medicine Subspecialities

RATIONALE & OBJECTIVES

Artificial intelligence driven by machine learning algorithms is being increasingly employed for early detection, disease diagnosis, and clinical management. We explored the use of machine learning-driven advancements in kidney research compared with other organ-specific fields.

STUDY DESIGN

Cross-sectional bibliometric analysis.

SETTING & PARTICIPANTS

ISI Web of Science database was queried using specific Medical Subject Headings (MeSH) terms about the organ system, journal International Standard Serial Number, and research methodology. In parallel, we screened the National Institutes of Health (NIH) RePORTER website to explore funded grants that proposed the use of machine learning as a methodology.

PREDICTORS

Number of publications using machine learning as a research method.

OUTCOME

Articles were characterized by research methodology among 5 organ systems (brain, heart, kidney, liver, and lung). Grants funded by NIH for machine learning were characterized by study sections.

ANALYTICAL APPROACH

Percentages of articles using machine learning and other research methodologies were compared among 5 organ systems.

RESULTS

Machine learning-based articles that are focused on the kidney accounted for 3.2% of the total relevant articles from the 5 organ systems. Specifically, brain research published over 19-fold higher number of articles than kidney research. As compared with machine learning, conventional statistical approaches such as the Cox proportional hazard model were used 9-fold higher in articles related to kidney research. In general, a lower utilization of machine learning-based approaches was observed in organ-specific specialty journals than the broad interdisciplinary journals. The digestive disease, kidney, and urology study sections funded 122 applications proposing machine learning-based approaches compared to 265 applications from the neurology, neuropsychology, and neuropathology study sections.

LIMITATIONS

Observational study.

CONCLUSIONS

Our analysis suggests lowest use of machine learning as a research tool among kidney researchers compared with other organ-specific researchers, underscoring a need to better inform the kidney research community about this emerging data analytic tool.

Clinical Characteristics and Outcomes of Adults with Nephrotic Syndrome Due to Minimal Change Disease

PURPOSE

Minimal change disease (MCD) is considered a relatively benign glomerulopathy, as it rarely progresses to end-stage kidney disease. The aim of this study was to describe the characteristics and outcomes of adults with MCD and identify potential risk factors for relapse.

PATIENTS & METHODS

We retrospectively studied a cohort of adults with biopsy-proven MCD in terms of clinical features and treatment outcomes. Baseline characteristics and outcomes were recorded and predictors of relapse were analyzed using logistic regression multivariate analysis.

RESULTS

59 patients with adult-onset primary MCD with nephrotic syndrome were included. Mean serum creatinine at diagnosis was 0.8 mg/dL (±2.5) and estimated GFR (eGFR) was 87 mL/min/1.73 m² (±29.5). Mean serum albumin was 2.5 g/dL (±0.8) and 24 h proteinuria 6.8 g (±3.7). Microscopic hematuria was detected in 35 (58.5%) patients. 42 patients received prednisone alone, six patients received prednisone plus cyclophosphamide, five patients received prednisone plus cyclosporine, one patient received prednisone plus rituximab and five patients did not receive immunosuppression at all since they achieved spontaneous remission. During a mean follow up time of 34.7(22.1) months, 46.1% of patients experienced at least one episode of relapse. The mean age of patients who did not experience a relapse was significantly higher than that of patients who relapsed while relapsers had a significantly longer duration of 24 h proteinuria prior to biopsy compared to non-relapsers. Overall, 10% of patients experienced acute kidney injury while the mean eGFR at the end was 82 mL/min/1.73 m² (±29.1) and one patient ended up in chronic dialysis. Overall, the proportion of non-relapsers, who experienced acute kidney injury (17%) was significantly higher than the one recorded among relapsers (0%).

CONCLUSION

In this series of patients, almost 46% of adult-onset nephrotic MCD patients experienced a relapse, although their renal progression was rare. Younger onset age was an independent risk factor for relapse in adult-onset MCD patients.

Deconvolution of Focal Segmental Glomerulosclerosis Pathophysiology Using Transcriptomics Techniques

Background

Focal segmental glomerulosclerosis is a histopathological pattern of renal injury and comprises a heterogeneous group of clinical conditions with different pathophysiology, clinical course, prognosis, and treatment. Nevertheless, subtype differentiation in clinical practice often remains challenging, and we currently lack reliable diagnostic, prognostic, and therapeutic biomarkers. The advent of new transcriptomics techniques in kidney research poses great potential in the identification of gene expression biomarkers that can be applied in clinical practice.

Summary

Transcriptomics techniques have been completely revolutionized in the last 2 decades, with the evolution from low-throughput reverse-transcription polymerase chain reaction and in situ hybridization techniques to microarrays and next-generation sequencing techniques, including RNA-sequencing and single-cell transcriptomics. The integration of human gene expression profiles with functional in vitro and in vivo experiments provides a deeper mechanistic insight into the candidate genes, which enable the development of novel-targeted therapies. The correlation of gene expression profiles with clinical outcomes of large patient cohorts allows for the development of clinically applicable biomarkers that can aid in diagnosis and predict prognosis and therapy response. Finally, the integration of transcriptomics with other "omics" modalities creates a holistic view on disease pathophysiology.

Key Messages

New transcriptomics techniques allow high-throughput gene expression profiling of patients with focal segmental glomerulosclerosis (FSGS). The integration with clinical outcomes and fundamental mechanistic studies enables the discovery of new clinically useful biomarkers that will finally improve the clinical outcome of patients with FSGS.

Peptide profiling in cow urine reveals molecular signature of physiology-driven pathways and in-silico predicted bioactive properties

Peptidomics allows the identification of peptides that are derived from proteins. Urinary peptidomics has revolutionized the field of diagnostics as the samples represent complete systemic changes happening in the body. Moreover, it can be collected in a non-invasive manner. We profiled the peptides in urine collected from different physiological states (heifer, pregnancy, and lactation) of Sahiwal cows. Endogenous peptides were extracted from 30 individual cows belonging to three groups, each group comprising of ten animals (biological replicates n = 10). Nano Liquid chromatography Mass spectrometry (nLC-MS/MS) experiments revealed 5239, 4774, and 5466 peptides in the heifer, pregnant and lactating animals respectively. Urinary peptides of <10 kDa size were considered for the study. Peptides were extracted by 10 kDa MWCO filter. Sequences were identified by scanning the MS spectra ranging from 200 to 2200 m/z. The peptides exhibited diversity in sequences across different physiological states and in-silico experiments were conducted to classify the bioactive peptides into anti-microbial, anti-inflammatory, anti-hypertensive, and anti-cancerous groups. We have validated the antimicrobial effect of urinary peptides on Staphylococcus aureus and Escherichia coli under an in-vitro experimental set up. The origin of these peptides was traced back to certain proteases viz. MMPs, KLKs, CASPs, ADAMs etc. which were found responsible for the physiology-specific peptide signature of urine. Proteins involved in extracellular matrix structural constituent (GO:0005201) were found significant during pregnancy and lactation in which tissue remodeling is extensive. Collagen trimers were prominent molecules under cellular component category during lactation. Homophilic cell adhesion was found to be an important biological process involved in embryo attachment during pregnancy. The in-silico study also highlighted the enrichment of progenitor proteins on specific chromosomes and their relative expression in context to specific physiology. The urinary peptides, precursor proteins, and proteases identified in the study offers a base line information in healthy cows which can be utilized in biomarker discovery research for several pathophysiological studies.

Towards harmony in defining and reporting glomerular diseases on kidney biopsy

PURPOSE OF REVIEW

To review recent efforts to develop uniformity and precision in defining individual glomerular histologic and ultrastructural lesions and proposals for developing greater uniformity in reporting of glomerular diseases.

RECENT FINDINGS

Over the past 2 decades, scoring systems for multiple glomerular diseases have emerged, as have several consortia for the study of glomerular diseases. However, one important limitation faced by renal pathologists and nephrologists has been a lack of uniformity and precision in defining the morphologic lesions seen by light and electron microscopy on which the scoring systems are based. In response to this, the Renal Pathology Society organized a working group that over 4 years arrived at consensus definitions for many such lesions. These definitions can be applied within the context of scoring systems for different glomerular diseases, and recently proposed reporting systems based on pathogenic categories and for defining the overall severity of chronic changes.

SUMMARY

From extensive discussions a panel of 13 renal pathologists reached consensus in defining 47 individual glomerular lesions seen on light microscopy and 56 glomerular lesions and key normal structures seen by electron microscopy. Validation of the impact of these consensus definitions on interobserver agreement in lesion identification is currently underway.

GWAS-Based Discoveries in IgA Nephropathy, Membranous Nephropathy, and Steroid-Sensitive Nephrotic Syndrome

Over the past decade, genome-wide association studies (GWAS) have emerged as a powerful tool to understand the genetic basis of complex traits in humans. The GWAS approach has been successfully applied to primary glomerular disorders, providing numerous novel insights into the genetic architecture of IgA nephropathy, membranous nephropathy, and steroid-sensitive nephrotic syndrome. IgA nephropathy appears to have a highly complex polygenic architecture, with nearly 20 genome-wide significant loci of small-to-moderate effects discovered to date. In contrast, the genetic susceptibility to membranous nephropathy and steroid-sensitive nephrotic syndrome appears to be driven by a small number of large-effect loci. The MHC locus on chromosome 6p21 is strongly associated with genetic susceptibility to all major types of immune-mediated glomerulopathies. However, a distinct set of classical HLA alleles is associated with each individual disease type, pinpointing to specific immune mechanisms underlying each of these conditions. Additional insights from the discovery of non-HLA risk loci reinforced the role of innate and adaptive immunity in the pathogenesis of these disorders, and highlighted important susceptibility overlaps between glomerular and other autoimmune and inflammatory conditions. Despite these initial successes, much larger GWAS and sequencing studies are still needed for each individual glomerular disease type. Increased power will be critical to comprehensively test for genetic effects across the full spectrum of allelic frequencies, to detect gene-gene and gene-environment interactions, and to potentially improve the performance of polygenic risk predictors. Moreover, the existing studies are limited mostly to European and East Asian populations, stressing the urgency to expand genetic discovery efforts to more diverse populations worldwide.

Improving data quality in observational research studies: Report of the Cure Glomerulonephropathy (CureGN) network

Background

High data quality is of crucial importance to the integrity of research projects. In the conduct of multi-center observational cohort studies with increasing types and quantities of data, maintaining data quality is challenging, with few published guidelines.

Methods

The Cure Glomerulonephropathy (CureGN) Network has established numerous quality control procedures to manage the 70 participating sites in the United States, Canada, and Europe. This effort is supported and guided by the activities of several committees, including Data Quality, Recruitment and Retention, and Central Review, that work in tandem with the Data Coordinating Center to monitor the study. We have implemented coordinator training and feedback channels, data queries of questionable or missing data, and developed performance metrics for recruitment, retention, visit completion, data entry, recording of patient-reported outcomes, collection, shipping and accessing of biological samples and pathology materials, and processing, cataloging and accessing genetic data and materials.

Results

We describe the development of data queries and site Report Cards, and their use in monitoring and encouraging excellence in site performance. We demonstrate improvements in data quality and completeness over 4 years after implementing these activities. We describe quality initiatives addressing specific challenges in collecting and cataloging whole slide images and other kidney pathology data, and novel methods of data quality assessment.

Conclusions

This paper reports the CureGN experience in optimizing data quality and underscores the importance of general and study-specific data quality initiatives to maintain excellence in the research measures of a multi-center observational study.