Validation of a histopathologic classification scheme for antineutrophil cytoplasmic antibody–associated glomerulonephritis

The prognostic value of two histopathologic classification models of ANCA-associated glomerulonephritis: a prospective study

BACKGROUND

Berden Classification and anti-neutrophil cytoplasmic antibody (ANCA) Renal Risk Score are classification models for rating renal histology and predicting outcome in patients with ANCA-associated Vasculitis/Glomerulonephritis (AAV/GN). In the present study we compare their ability to predict renal function outcome in short- and long-term follow up.

METHODS

Patients with an initial diagnosis of AAV/GN based on kidney biopsy were classified according to Berden and Renal Risk Score, started on the same treatment protocol, and were followed prospectively for up to 60 months. Renal function was recorded at 3mo(T3), 6mo(T6) and 60mo(T60), and results were compared to both classification systems.

RESULTS

Ninety four AAV/GN patients, M/F = 36/58, age = 60.05 (18-82)yrs were included. Based on Berden classification, patients grouped as Focal (n = 24), Crescentic (n = 35), Mixed (n = 21) and Sclerotic (n = 14), had significant differences in estimated glomerular filtration rate (eGFR) only at T3, while the percentage of those requiring hemodialysis differed at T0, T3, T6 but not at T60. According to the Renal Risk Score, patients were classified as Low (n = 8), Medium (n = 47) and High (n = 39) risk, and showed significant differences in both eGFR levels, proportion of hemodialysis, at T0, T3, T6 and end-stage kidney disease (ESKD) at T60. Even patients classified as Mixed (Berden) and as Medium or High risk (Renal Risk Score) had significant improvement from T0 to T6. Relapse could not be predicted by either system.

CONCLUSION

Both methods were able to predict short-term renal function outcome and need for hemodialysis, but the Renal Risk Score showed significant superiority in predicting renal function outcome and ESKD after long-term follow up.

Renal histopathological predictors of end-stage kidney disease in ANCA-associated vasculitis with glomerulonephritis: a single-centre study in Korea

This study investigated whether histopathological classification and histologic lesion scores could significantly and independently predict the progression to end-stage kidney disease (ESKD) in Korean patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis-glomerulonephritis (AAV-GN). This study included 113 patients with AAV-GN confirmed by kidney biopsy. The glomerular, tubulointerstitial, and vascular lesions were systematically assessed using a scoring system. The scoring system was adopted from the Banff scoring system but also the Oxford study and the revision of the ISN/RPS. For comparison, the scores were classified into two groups; the low, and the high, and the difference was investigated between ESKD and non-ESKD groups using Cox proportional analysis. At diagnosis, the median age was 59.0 years and 33.6% were males. Of 113 patients, 44.2% had ESKD progression during follow-up. There were significant differences in several kidney-, inflammation-, and AAV-pathogenesis-related variables between AAV-GN patients with ESKD and those without. The sclerotic class exhibited the worst renal prognosis among the four histopathological classes. Among histopathological features, high interstitial fibrosis, tubular atrophy and global glomerulitis scores were significantly associated with ESKD progression. Whereas multivariable Cox analysis revealed only a high global glomerulitis score which means global endocapillary hypercellularity in a larger number of glomeruli is an independent predictor of ESKD progression. Moreover, among clinical and histopathological features, a high global glomerulitis score could also predict ESKD progression in addition to serum blood urea nitrogen and creatinine. This study demonstrated the worst renal prognosis for the sclerotic class and first discovered that a high global glomerulitis score was an independent predictor of ESKD in patients with AAV-GN.

Outcomes in ANCA-Associated Vasculitis in Scotland: Validation of the Renal Risk Score in a Complete National Cohort

Introduction

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) causes autoimmune-mediated inflammation of small blood vessels in multiple organs, including the kidneys. The ability to accurately predict kidney outcomes would enable a more personalized therapeutic approach.

Methods

We used our national renal biopsy registry to validate the ability of ANCA Renal Risk Score (ARRS) to predict end-stage kidney disease (ESKD) for individual patients. This score uses histopathological and biochemical data to stratify patients as high, medium, or low risk for developing ESKD.

Results

A total of 288 patients were eligible for inclusion in the study (low risk n = 144, medium risk n = 122, high risk n = 12). Using adjusted Cox proportional hazard models with the low-risk group as reference, we show that outcome differs between the categories: high-risk hazard ratio (HR) 16.69 (2.91-95.81, P = 0.002); medium risk HR 4.14 (1.07-16.01, P = 0.039). Incremental multivariable-adjusted Cox proportional hazards models demonstrated that adding ARRS to a model adjusted for multiple clinical parameters enhanced predictive discrimination (basic model C-statistic 0.864 [95% CI 0.813-0.914], basic model plus ARRS C-statistic 0.877 [95% CI 0.823-0.931]; P <0.01).

Conclusion

The ARRS better discriminates risk of ESKD in AAV and offers clinicians more prognostic information than the use of standard biochemical and clinical measures alone. This is the first time the ARRS has been validated in a national cohort. The proportion of patients with high-risk scores is lower in our cohort compared to others and should be noted as a limitation of this study.

Prognostic factors associated with advanced chronic kidney disease in a cohort of patients with ANCA vasculitis and renal involvement

OBJECTIVE

The aim of this study was to evaluate prognostic factors associated with advanced chronic kidney disease (ACKD) in a cohort of patients with ANCA-associated vasculitis and renal involvement.

METHODS

Observational retrospective study. We included patients with biopsy-proven ANCA glomerulonephritis (GN) diagnosed between 2001 and 2016, with at least 1-year follow-up. Data were recorded at diagnosis, end of induction, after 12 months of treatment, and at the end of follow-up. We analysed clinical-analytical data and renal histopathology, as well as treatments, dialysis requirement, relapses and death. Univariate analysis was performed to identify factors associated with long-term ACKD (eGFR < 30 ml/min). Multivariate analysis using an alternative outcome (eGFR at the end of follow-up) was performed. Diagnostic accuracy for ACKD of each predictor variable was compared using AUC of ROC curves.

RESULTS

Sixty patients were included: 17 GPA, 14 MPA, 5 EGPA, and 24 RLV. Forty-six patients were women (76.7%). Mean age at diagnosis was 67.8 years (SD 13.1), and median follow-up time was 4.2 years (IQR 2.2-6.8). At the end of follow-up, 12 patients (20.0%) had an eGFR < 30 ml/min. Univariate analysis showed a statistically significant association of ACKD with sclerotic class biopsy (OR 7.17, 95% CI 1.34-38.31), 12-month proteinuria (OR 5.16, 95% CI 1.16-22.87), and creatinine at diagnosis (OR 1.24, 95% CI 1.02-1.52), end of induction (OR 15.40, 95% CI 2.41-98.28), and after 12 months (OR 19.25, 95% CI 2.75-134.92). In the multivariate analysis, eGFR at baseline (< 0.001), after 6 months (< 0.001) and 12 months of treatment (< 0.001), remained statistically associated with eGFR at the end of follow-up. The best diagnostic accuracy in ROC curves was shown by serum creatinine at the end of induction treatment (AUC 0.93) and after 12 months (AUC 0.94).

CONCLUSION

In this cohort of patients with ANCA GN, creatinine and eGFR at baseline and after 6 and 12 months of treatment were the best predictors of ACKD at the end of follow-up.

Modified histopathological classification with age-related glomerulosclerosis for predicting kidney survival in ANCA-associated glomerulonephritis

BACKGROUND

The histopathological classification of ANCA-GN divides patients into four groups based on signs of glomerular injury. However, this classification did not consider age-related glomerulosclerosis. In this study, we aimed to compare the prediction of renal survival between Berden's ANCA-GN histopathological classification and ANCA-GN histopathological classification modified with age-related glomerulosclerosis.

METHODS

Between January 2004 and December 2019, 65 patients diagnosed with ANCA-GN were enrolled. Demographic, laboratory, and histopathologic findings were retrospectively analyzed. Renal survival analyses were compared according to classical and modified ANCA-GN histopathological classifications. Multivariate Cox regression analysis for the factors affecting renal survival was performed.

RESULTS

In Berden's ANCA-GN histopathological classification, 15 patients were in the focal group, 21 in the crescentic, 21 in the sclerotic, and 8 in the mixed group. The ANCA-GN histopathological classification model generated statistically significant predictions for renal survival (p = 0.022). When the histopathological classification was modified with age-related glomerulosclerosis, eight of the nine patients previously classified in the sclerotic group were classified in the mixed and one in the crescentic groups. Modification of histopathological classification with age-related glomerulosclerosis increases the statistical significance in renal survival analysis (p = 0.009). The multivariate Cox regression analysis showed that the disease-related global sclerotic glomeruli percentage and serum creatinine level were significant independent factors.

CONCLUSION

Modification of Berden's ANCA-GN histopathological classification model with age-related glomerulosclerosis may increase the statistical significance of the histopathological classification model.

Histopathological prognostic factors in ANCA-associated glomerulonephritis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) are a group of multisystemic autoimmune diseases characterized by necrotizing inflammation of small vessels. Kidney involvement is frequent in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), and accounts for a significant proportion of the morbidity and mortality related to these diseases. Despite improvement in therapeutic management of ANCA-glomerulonephritis (ANCA-GN), end-stage kidney disease (ESKD) still occurs in up to 30% of affected patients within 5 years following diagnosis. Thus, identifying patients for whom aggressive immunosuppressive therapy will be more beneficial than deleterious is of great importance. Several clinical, biological and histological factors have been proposed as predictors of ESKD. The kidney biopsy is essential not only for the diagnosis, but also for evaluating renal prognosis. In this review, we discuss the prognostic value of renal lesions at the diagnosis of ANCA-GN by analyzing each compartment of the nephron. We also review existing ESKD risk classification in ANCA-GN and finally propose an example of a standardized pathology report that could be used in routine practice.

Reappraisal of Renal Arteritis in ANCA-associated Vasculitis: Clinical Characteristics, Pathology, and Outcome

BACKGROUND

Renal involvement in ANCA-associated vasculitis (AAV) is associated with poor outcomes. The clinical significance of arteritis of the small kidney arteries has not been evaluated in detail.

METHODS

In a multicenter cohort of patients with AAV and renal involvement, we sought to describe the clinicopathologic characteristics of patients with AAV who had renal arteritis at diagnosis, and to retrospectively analyze their prognostic value.

RESULTS

We included 251 patients diagnosed with AAV and renal involvement between 2000 and 2019, including 34 patients (13.5%) with arteritis. Patients with AAV-associated arteritis were older, and had a more pronounced inflammatory syndrome compared with patients without arteritis; they also had significantly lower renal survival (P=0.01). In multivariable analysis, the ANCA renal risk score, age at diagnosis, history of diabetes mellitus, and arteritis on index kidney biopsy were independently associated with ESKD. The addition of the arteritis status significantly improved the discrimination of the ANCA renal risk score, with a concordance index (C-index) of 0.77 for the ANCA renal risk score alone, versus a C-index of 0.80 for the ANCA renal risk score plus arteritis status (P=0.008); ESKD-free survival was significantly worse for patients with an arteritis involving small arteries who were classified as having low or moderate risk, according to the ANCA renal risk score. In two external validation cohorts, we confirmed the incidence and phenotype of this AAV subtype.

CONCLUSIONS

Our findings suggest AAV with renal arteritis represents a different subtype of AAV with specific clinical and histologic characteristics. The prognostic contribution of the arteritis status remains to be prospectively confirmed.

Systematic Scoring of Tubular Injury Patterns Reveals Interplay between Distinct Tubular and Glomerular Lesions in ANCA-Associated Glomerulonephritis

Background: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a small vessel vasculitis, most frequently presenting as microscopic polyangiitis (MPA) or granulomatosis with polyangiitis (GPA). Acute tubular injury with the presence of tubulitis was previously reported to be of prognostic value in ANCA glomerulonephritis (GN). In particular, distinct tubular injury lesions were associated with the deterioration of kidney function at AAV disease onset, as well as renal resistance to treatment, and higher risk of progression to composite outcome in patients with AAV. To expand our knowledge regarding distinct tubular lesions in AAV, we aimed to describe acute tubular injury patterns in association with glomerular lesions in ANCA GN by systematic histological scoring. Methods: A total number of 48 renal biopsies with confirmed renal involvement of AAV admitted to the University Medical Center Göttingen from 2015 to 2020 were retrospectively examined. By systematic scoring of tubular injury lesions, the association between clinical parameters, laboratory markers, and histopathological findings was explored. Results: We have shown that cellular casts in renal biopsies were frequently observed in the majority of cases with ANCA GN. Furthermore, we showed that tubular epithelial simplification with dilatation correlated with MPA and MPO subtypes, C3c hypocomplementemia, severe renal involvement, and uACR. Red blood cell (RBC) casts were associated with increased levels of C-reactive protein (CRP), leukocyturia, and hematuria. Finally, we found that hyaline casts were associated with an increased fraction of glomeruli with global glomerular sclerosis. Conclusions: Acute tubular injury patterns were correlated with active ANCA GN, whereas tubular injury lesions reflecting the later stages of kidney disease correlated with chronic glomerular lesions. These results suggest an interplay between different renal compartments.

Muscle biopsy in anti-neutrophil cytoplasmic antibody-associated vasculitis: diagnostic yield depends on anti-neutrophil cytoplasmic antibody type, sex and neutrophil count

OBJECTIVES

This study aimed to examine the sensitivity of muscle biopsy (MB) in ANCA-associated vasculitis (AAV), identify factors predicting MB positivity and assess the prognostic value of a positive MB.

METHODS

We conducted a single-centre retrospective study of AAV with an MB performed at diagnosis. AAV classification [granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA)] followed the European Medicines Agency algorithm. A logistic regression model was used to identify the factors associated with MB positivity. Survival curves were generated using the Kaplan-Meier method.

RESULTS

Among 276 AAV patients (1995-2018), 101 had an MB. Seventy-eight patients were included: 33 with GPA, 25 with MPA and 20 with EGPA. MB samples were positive in 45 cases (58%): 17 GPA, 16 MPA and 12 EGPA. Univariate analysis focussed on GPA and MPA, revealed that the MB yield was higher in females [22/31 (71%) vs 11/27 (41%); P = 0.02] and in anti-MPO patients [25/37 (68%) vs 6/19 (32%) for anti-PR3; P = 0.01]. By multivariate analysis, three factors predicted MB positivity: anti-MPO ANCA [odds ratio (OR) 10.67 (CI 2.09, 81.68)], female sex [OR 5.3 (CI 1.16, 32.35)] and neutrophil count [OR 1.33 (CI 1.07, 1.8)]. MB positivity had no impact on relapse, death or end-stage renal disease-free survival.

CONCLUSIONS

MB is a safe and efficient diagnostic tool for AAV. Predictors of MB yield include ANCA type, sex and neutrophil count. MB cannot substitute for kidney biopsy when indicated, but should be considered in other cases.

Proteinuria Indicates Decreased Normal Glomeruli in ANCA-Associated Glomerulonephritis Independent of Systemic Disease Activity

Background: Renal involvement is a common and severe complication of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), potentially resulting in a pauci-immune necrotizing and crescentic ANCA glomerulonephritis (GN) with acute kidney injury (AKI), end-stage renal disease (ESRD) or death. There is recent evidence that the degree of proteinuria at diagnosis is associated with long-term renal outcome in ANCA GN. Therefore, we here aimed to systematically describe the association between proteinuria and clinicopathological characteristics in 53 renal biopsies with ANCA GN and corresponding urinary samples at admission. Methods: A total number of 53 urinary samples at admission and corresponding renal biopsies with confirmed renal involvement of AAV were retrospectively included from 2015 to 2021 in a single-center study. Results: Proteinuria correlated with myeloperoxidase (MPO) subtype, diagnosis of microscopic polyangiitis (MPA) and severe deterioration of kidney function. Proteinuria was most prominent in sclerotic class ANCA GN and ANCA renal risk score (ARRS) high risk attributed to nonselective proteinuria, including both glomerular and tubular proteinuria. Finally, there was no association between proteinuria and systemic disease activity, suggesting that proteinuria reflected specific renal involvement in AAV rather that systemic disease activity. Conclusions: In conclusion, proteinuria correlated with distinct clinicopathological characteristics in ANCA GN, mostly attributed to a reduced fraction of normal glomeruli. Furthermore, proteinuria in ANCA GN reflected specific renal involvement in AAV rather than systemic disease activity. Therefore, urinary findings could further improve our understanding of mechanisms promoting kidney injury and progression of ANCA GN.

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.

Histopathological Findings Predict Renal Recovery in Severe ANCA-Associated Vasculitis Requiring Intensive Care Treatment

Renal involvement is a common and severe complication of AAV as it can cause ESRD. Histopathological subgrouping and ARRS are helpful to predict long-term ESRD in patients with AAV. Because a subgroup of critically ill patients with severe AAV present with deterioration of kidney function requiring RRT at admission, we here aimed to evaluate histopathological findings and predictive value of Berden's histopathological subgrouping and ARRS for severity of AKI and requirement of RRT during the short-term clinical course in critically ill patients requiring intensive care treatment and predictors for short-term renal recovery in patients requiring RRT. A subgroup of 15/46 (32. 6%) AAV patients with biopsy-proven AAV required RRT during the short-term course of disease, associated with requirement of critical care treatment. While histopathological subgrouping and ARRS were associated with requirement of acute RRT, presence of global glomerular scarring was the strongest predictor of failure to recover from RRT after initiation of remission induction therapy. This new aspect requires further investigation in a prospective controlled setting for therapeutic decision making especially in this subgroup.

Developments in the Histopathological Classification of ANCA-Associated Glomerulonephritis

BACKGROUND AND OBJECTIVES

The histopathologic classification for ANCA-associated GN distinguishes four classes on the basis of patterns of injury. In the original validation study, these classes were ordered by severity of kidney function loss as follows: focal, crescentic, mixed, and sclerotic. Subsequent validation studies disagreed on outcomes in the crescentic and mixed classes. This study, driven by the original investigators, provides several analyses in order to determine the current position of the histopathologic classification of ANCA-associated GN.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A validation study was performed with newly collected data from 145 patients from ten centers worldwide, including an analysis of interobserver agreement on the histopathologic evaluation of the kidney biopsies. This study also included a meta-analysis on previous validation studies and a validation of the recently proposed ANCA kidney risk score.

RESULTS

The validation study showed that kidney failure at 10-year follow-up was significantly different between the histopathologic classes (P<0.001). Kidney failure at 10-year follow-up was 14% in the crescentic class versus 20% in the mixed class (P=0.98). In the meta-analysis, no significant difference in kidney failure was also observed when crescentic class was compared with mixed class (relative risk, 1.15; 95% confidence interval, 0.94 to 1.41). When we applied the ANCA kidney risk score to our cohort, kidney survival at 3 years was 100%, 96%, and 77% in the low-, medium-, and high-risk groups, respectively (P<0.001). These survival percentages are higher compared with the percentages in the original study.

CONCLUSIONS

The crescentic and mixed classes seem to have a similar prognosis, also after adjusting for differences in patient populations, treatment, and interobserver agreement. However, at this stage, we are not inclined to merge the crescentic and mixed classes because the reported confidence intervals do not exclude important differences in prognosis and because an important histopathologic distinction would be lost.

Pathological severity determines the renal recovery for anti-myeloperoxidase antibody-associated vasculitis requiring dialysis at disease onset: a retrospective study

Background

Many patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) need dialysis at disease onset due to severe kidney injury. Determining whether they can become dialysis independent is an important clinical assessment.

Methods

Forty kidney biopsy-proved myeloperoxidase (MPO)-ANCA associated AAV patients who required dialysis at disease onset were enrolled. Relationships between laboratory and pathological characteristics and prognoses were analyzed.

Results

Twenty-five patients obtained dialysis independence within 3 months, while the other 15 patients remained dialysis dependent. No sclerotic class was identified among the 40 patients. Only two biopsies exhibited focal class diagnoses and both these patients recovered their renal function. The renal recovery rate of the 20 patients with mixed class was significantly lower than that of the 18 patients with crescentic class (40.0% vs. 83.3%, p = 0.006). Receiver operating characteristics (ROC) curves showed fibrous crescent+global glomerulosclerosis greater than 32.6% was a strong predictor of dialysis dependence with a sensitivity of 93.3% and specificity of 88.0%. When the percentage of fibrous crescent+global glomerulosclerosis exceeded 47.9%, dialysis independence was not possible. Correlation analysis indicated that platelet counts were negatively correlated with the percentage of fibrous crescent+global glomerulosclerosis (R = -0.448, p = 0.004). Most patients with increased platelets (84.62%) obtained renal recovery. Compared with methylprednisolone pulse therapy, plasma exchange accelerated renal recovery (29.4 ± 15.6 vs. 41.4 ± 11.7 days, p = 0.039).

Conclusions

For MPO-ANCA AAV who required dialysis at disease onset, crescentic and mixed classes accounted for the majority of patients in our cohort. The renal outcome of mixed class patients was worse than that of crescentic class. A high proportion of fibrous crescent+global glomerulosclerosis is a predictor of dialysis dependence. Increased platelet count is associated with active and reversible renal lesions.

Estimating the Change in Renal Function During the First Year of Therapy in ANCA-Associated Vasculitis

Introduction

Studies in antineutrophil cytoplasmic autoantibody (ANCA)–associated vasculitis (AAV) consistently show that the months following diagnosis have the greatest impact on the long-term renal function. Yet, it remains uncertain how much early gain should be expected with treatment. We sought to determine the factors associated with the change in glomerular filtration rate (GFR) throughout the first year.

Methods

We retrospectively reviewed patients from 3 university hospitals who received treatments. We assessed the proportions of glomeruli with crescents, with global sclerosis, the AAV glomerulonephritis classification, the severity of chronic vascular and tubulo-interstitial disease, and the presence of acute tubular injury (ATI). We used repeated-measures analyses of variance (ANOVAs) to determine factors associated with the change in GFR throughout the first year.

Results

There were 162 individuals with AAV identified, 96 with a valid renal biopsy and 82 with at least 12 months of follow-up. The initial GFR of 30 ± 25 ml/min per 1.73 m² rose by 15 ± 20 during the first year. The severity of pathology findings, myeloperoxidase positivity, and those with kidney- and lung-limited disease presented with a lower GFR. Younger patients with a lower initial GFR and the presence of ATI correlated with a greater increase in GFR by 12 months. A higher proportion of crescents did not predict the change in GFR, contrary to global glomerulosclerosis, where each 10% increase added a loss of 2.7 ± 1.3 ml/min per 1.73 m² per year (P = 0.03). These factors remained independent of each other.

Conclusion

Multiple factors influence renal recovery during the first year of therapy. Estimating the change in GFR early on will help identify and reassess outliers.

Prognostic Factors in Anti-Neutrophil Cytoplasmic Antibody-Associated Glomerulonephritis with Severe Glomerular Sclerosis: A National Registry-Based Cohort Study

Background

Classification of patients with anti-neutrophil cytoplasmic antibody-associated glomerulonephritis (ANCA-GN) into histological classes is useful for predicting a patient's risk of progression to end-stage renal disease (ESRD). However, even in the worst prognostic group, the 5-year end-stage renal disease-free survival rate is as high as 50%.

Objectives

To investigate those prognostic factors indicative of progression to ESRD in patients with ANCA-GN and sclerosing histology.

Methods

Patients from the Norwegian Kidney Biopsy Registry between 1991 and 2012 who had biopsy verified pauci-immune glomerulonephritis, positive ANCA serology, and sclerosing histology were included. Cases with ESRD during follow-up were identified via linkage with the Norwegian Renal Registry. Potential prognostic factors with relevant cut-offs were compared in patients with and without progression to ESRD during follow-up.

Results

Of 23 included patients, 10 progressed to ESRD. ESRD patients had a lower initial estimated glomerular filtration rate (eGFR; 21 versus 52 ml/min/1.73 m²) and a lower percentage of normal glomeruli (4% versus 15%). Five-year risks of ESRD with eGFR >15 versus ≤15 ml/min/1.73 m² were 77% and 15%, with percentage normal glomeruli >10% versus ≤10%, 83% and 39%.

Conclusions

eGFR and percentage of normal glomeruli are strong risk factors for ESRD in ANCA-GN with sclerosing histology.

Prognosis and Histological Classification in Elderly Patients with ANCA-Glomerulonephritis: A Registry-Based Cohort Study

Background

The value of a histologic classification scheme to classify patients with anti-neutrophil cytoplasmic antibody-associated glomerulonephritis (ANCA-GN) into focal, mixed, crescentic, and sclerotic types for predicting risk of end-stage renal disease (ESRD) is well documented. However, the prognostic value of histological classification specifically in elderly patients (≥70 years) with ANCA-GN has not previously been investigated.

Methods

Patients with biopsy-verified pauci-immune necrotizing glomerulonephritis were identified from the Norwegian Kidney Biopsy Registry between 1991 and 2012 and those ≥70 years of age at the time of diagnosis and having positive anti-neutrophil cytoplasmic antibody serology were included in this study. The incidence rate of ESRD and/or death was determined by linking the study cohort to the Norwegian Renal Registry and the Population Registry of Norway. The ESRD-free survival and patient survival were compared between the 4 histological types.

Results

Of the 81 patients included, 20 progressed to ESRD and 34 died. The 1-year and 5-year ESRD-free survival varied between histological groups (p = 0.003) as follows: focal, 97% and 97%, respectively; mixed, 70% and 57%; crescentic, 76% and 63%; and sclerotic, 49% and 49%. Patient survival did not differ significantly between groups (p = 0.30).

Conclusion

Histological classification in elderly patients with ANCA-GN is useful for predicting ESRD but not survival.

Histopathological Classification-A Prognostic Tool for Rapidly Progressive Glomerulonephritis

Background: Recently proposed histopathological classification may predict patient outcome in pauci-immune glomerulonephritis. This study sought to prove that the prognostic effect could be extended to all types of rapidly progressive glomerulonephritis. Methods: Retrospective analysis of patients diagnosed with rapidly progressive glomerulonephritis between April 1999 and August 2015 was performed. Epidemiological and clinical data were collected from medical records. The descriptions of renal biopsies were reviewed and classified into focal, sclerotic, crescentic and mixed class according to classification proposed by Berden et al. The study end points were end stage renal disease (ESRD) or death. Survival analyses were modelled using Cox regression. Results: 73 renal biopsies with diagnosis of rapidly progressive glomerulonephritis were included in the study. 25 (34.2%), 16 (21.9%), 24 (32.9%) and 8 (11%) patients were assigned to focal, crescentic, mixed and sclerotic class, respectively. Thirty-two (42.5%) patients were anti-neutrophil cytoplasmic antibody (ANCA) negative, of which eight (10.9%) were anti–glomerular basement membrane antibody (anti–GBM) positive and 24 (32.8%) were negative for autoimmune antibodies. Six (8.2%) patients died within one year. Among patients who survived, median change in estimated glomerular filtration rate (eGFR) values were: −10.5 mL/min in focal, 4.2 mL/min in crescentic, −4.3 mL/min in mixed and 4.1 mL/min in sclerotic group, p > 0.05. In the Cox regression model, there was no significant predictor of patient survival whereas the sclerotic group (HR 3.679, 95% CI, 1.164–11.628, p < 0.05) and baseline eGFR of <15 mL/min (HR 4.832, 95% CI, 1.55–15.08, p < 0.01) had an unfavorable effect for renal survival. Conclusions: Predominant glomerular sclerosis and low eGFR at baseline are associated with higher risk of ESRD in cases with crescentic glomerulonephritis. Therefore, despite the origin of injury, histological classification might aid in prediction of patient outcomes in rapidly progressive glomerulonephritis.

End-stage renal disease in ANCA-associated vasculitis

The outcomes in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis have improved significantly over the past decades, although a significant proportion of them still reach end-stage renal disease (ESRD). Renal replacement therapy (RRT) is associated with a relatively low risk of relapsing vasculitis as a result of anti-rejection treatment after kidney transplantation or quiescence of the autoimmune process in haemodialysis patients, but a flare of vasculitis in the latter setting presents a challenge because the treatment is poorly tolerated. There are benefits of rituximab in haemodialysed patients, as it is more steroid sparing in the treatment of extrarenal disease. More favourable outcomes of kidney transplantation compared with haemodialysis support its use as a preferable method of RRT in patients with vasculitis remission or low disease activity.

Long-term renal outcome in pediatric glomerulonephritis associated with crescent formation

BACKGROUND

Information on long-term renal outcome of pediatric glomerulonephritis associated with crescent formation is limited. A single center retrospective study was conducted to assess long-term renal survival and to determine whether the 2010 classification for antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis can predict renal outcome in pediatric glomerulonephritis associated with crescent formation.

METHODS

Biopsy and clinical data of children, aged ≤ 18 years with ≥ 10 glomeruli and ≥ 10% crescentic glomeruli during January 1998 to December 2015, were reviewed. Biopsies were classified according to the 2010 classification into focal, crescentic, mixed, and sclerotic classes. The clinical endpoint was end-stage renal disease (ESRD).

RESULTS

Of 72 children, 14 patients (19.4%) had positive ANCA. The biopsy indication was rapidly progressive glomerulonephritis in 38 patients (52.8%) and 22 patients (30.6%) required dialysis at onset. Lupus nephritis was the most common diagnosis (43.1%), followed by IgA nephropathy/Henoch-Schoenlein purpura (HSP) (22.2%). ESRD occurred in 18 patients (25%) and the risk of ESRD differed among the histological classifications (p < 0.001). Dialysis at onset and sclerotic class was independent predictors of ESRD in an adjusted model. The risk of ESRD was four-fold higher in patients requiring dialysis at onset and 7.7-fold higher in sclerotic patients than in crescentic patients.

CONCLUSIONS

The probability of ESRD was substantial in pediatric glomerulonephritis associated with crescent formation. The 2010 classification is useful for establishing long-term renal prognosis. Future research is required to validate whether histological classification could be a determinant in therapeutic guideline modification, since long-term renal prognosis is different in each class.

Risk Factors for Renal Survival in Chinese Patients with Myeloperoxidase-ANCA-Associated GN

BACKGROUND AND OBJECTIVES

Our study explored the association of histopathologic classification of ANCA-associated GN with renal survival in Chinese patients with myeloperoxidase-ANCA-associated GN.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Two hundred fifteen patients with biopsy-proven myeloperoxidase-ANCA-associated GN were included from January of 1996 to December of 2014. The biopsies included focal (n=27), mixed (n=82), crescentic (n=47), and sclerotic (n=59) classes. The long-term renal outcome and risk factors of myeloperoxidase-ANCA-associated GN for different histopathologic classes were retrospectively analyzed.

RESULTS

During a median follow-up time of 22 (9-51) months, 88 (40.9%) patients reached ESRD. The 5-year renal survival (overall 58.7%) was highest in the focal class (100.0%) and lowest in the sclerotic class (20.7%), with no difference between the mixed (58.9%) and crescentic (67.4%) classes. Patients in the mixed (hazard ratio, 0.34; 95% confidence interval, 0.20 to 0.57; P<0.001) and crescentic (hazard ratio, 0.31; 95% confidence interval, 0.16 to 0.59; P<0.001) classes were at lower risk for ESRD compared with patients in the sclerotic class, as were patients who received glucocorticoids plus mycophenolate mofetil (hazard ratio, 0.32; 95% confidence interval, 0.18 to 0.60; P<0.001) compared with those receiving glucocorticoids alone. In addition, patients with a serum creatinine level ≥4 mg/dl (hazard ratio, 2.93; 95% confidence interval, 1.77 to 4.85; P<0.001) or hypoalbuminemia (hazard ratio, 2.11; 95% confidence interval, 1.32 to 3.34; P=0.002) were at higher risk for ESRD. A serum creatinine level ≥4 mg/dl and a percentage of global sclerotic glomeruli ≥60% were the two independent risk factors for ESRD in the sclerotic class.

CONCLUSIONS

The histopathologic classification of ANCA-associated GN in combination with serum creatinine and serum albumin levels and treatment regimen is associated with renal outcome in myeloperoxidase-ANCA-associated GN. The evaluation of serum creatinine level and percentage of global sclerotic glomeruli provides additional information on the risk of renal survival in the sclerotic class of myeloperoxidase-ANCA-associated GN.

Histopathological Classification and Renal Outcome in Patients with Antineutrophil Cytoplasmic Antibodies-associated Renal Vasculitis: A Study of 186 Patients and Metaanalysis

Objective.

Renal vasculitis is one of the most common manifestations of antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) and renal histology is a key predictor of the outcome. A new histopathologic classification was proposed and validated, but the results are still debated.

Methods.

We performed a retrospective analysis to validate the histopathologic classification and performed a metaanalysis to evaluate its predictive value. There were 186 patients with ANCA-associated renal vasculitis diagnosed at Ruijin Hospital who were enrolled in the retrospective study. The metaanalysis considered the data for 1601 patients.

Results.

In our retrospective study, patients with focal class had the best renal outcome while patients with mixed class had the worst (p < 0.001). Metaanalysis showed that patients with focal class had better renal outcome than did those with crescentic class [risk ratio (RR) 0.23, 95% CI 0.16–0.34, p < 0.00001], with no evidence of heterogeneity (I2 = 0%, p = 0.96). Patients with crescentic class had better renal outcome than did those with sclerotic class (RR 0.52, 95% CI 0.41–0.64, p < 0.00001), with no evidence of heterogeneity (I2 = 2%, p = 0.43). We did not find statistical significance regarding renal outcome between mixed and crescentic classes (RR 1.14, 95% CI 0.91–1.43, p = 0.27), with no evidence of heterogeneity (I2 = 23%, p = 0.19). The retrospective study showed that lung and upper respiratory tract involvement were the most common extrarenal manifestations.

Conclusion.

We demonstrated the clinical utility of histopathologic classification in determining renal outcome in patients with AAV. Metaanalysis showed that patients with focal class had the best outcome while sclerotic class had the worst.

Prognostic Value of Histologic Classification of ANCA-Associated Glomerulonephritis

BACKGROUND AND OBJECTIVES

A kidney biopsy is preferred for the diagnosis of ANCA-associated vasculitis with renal involvement. The aim of our study was to evaluate the prognostic value of a histopathologic classification scheme recently proposed by an international consortium of renal pathologists in a large Norwegian cohort.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients diagnosed with ANCA-associated GN were included from the Norwegian Kidney Biopsy Registry 1991-2012. Renal morphology was classified as focal, mixed, crescentic, or sclerotic. Study end point was ESRD. Patients were followed from kidney biopsy to end of 2012.

RESULTS

Two hundred fifty patients with ≥10 glomeruli in the biopsy were included in our study. During a median follow-up of 3.5 years (0.7-7.6), 60 cases of ESRD occurred. Ninety-six (38%) biopsies were classified as focal, 61 (24%) biopsies were classified as mixed, 71 (28%) biopsies were classified as crescentic, and 22 (9%) biopsies were classified as sclerotic; 1- and 5-year cumulative renal survival rates were 96% and 90%, respectively, for the focal class, 86% and 75%, respectively, for the mixed class, 81% and 69%, respectively, for the crescentic class, and 56% and 51%, respectively, for the sclerotic class. By multivariate Cox regression analyses, the sclerotic class had a significantly worse renal prognosis than the focal (hazard ratio, 9.65; 95% confidence interval, 2.38 to 39.16) or combined mixed/crescentic classes (hazard ratio, 3.27; 95% confidence interval, 1.41 to 7.61), but no significant differences in outcome were observed in the crescentic class compared with the mixed class (hazard ratio, 1.13; 95% confidence interval, 0.44 to 2.87) or the combined mixed/crescentic class compared with the focal class (hazard ratio, 1.93; 95% confidence interval, 0.61 to 6.12). Accuracy by receiver operator characteristic curve analysis was estimated to be 0.72 (95% confidence interval, 0.65 to 0.80). In 108 additional patients with three to nine glomeruli in the biopsy, the prognostic value of this classification scheme was unchanged.

CONCLUSIONS

The histopathologic classification is a predictor of renal outcome of moderate quality. Merging the mixed and crescentic classes in the future could simplify the scheme.

Pauci-Immune Crescentic Glomerulonephritis: An ANCA-Associated Vasculitis

Rapidly progressive glomerulonephritis (RPGN) is a syndrome signified by a precipitous loss of renal function, with features of glomerulonephritis including dysmorphic erythrocyturia and glomerular proteinuria. RPGN is associated with extensive crescent formation, and, thus, the clinical term RPGN is often used interchangeably with the pathologic term crescentic glomerulonephritis (CGN). From an immunopathologic standpoint, primary RPGN is divided into pauci-immune GN (PICG), anti-GBM GN, and immune complex GN. PICG, the most common etiology of primary RPGN, refers to a necrotizing glomerulonephritis with few or no immune deposits by immunofluorescence (IF) or electron microscopy (EM). In most patients, pauci-immune CGN is a component of a systemic small vessel vasculitis such as granulomatosis with polyangiitis (GPA). Approximately 90% of patients with PICG have circulating ANCA antibodies, leading to the nomenclature ANCA-associated vasculitis (AAV). Recent research has identified several other antibodies associated with PICG, which is now understood to be a complex spectrum of disease with considerable overlap in terms of clinical phenotype and outcomes. In addition, several genetic and environmental factors have recently been implicated in the pathogenesis of this disorder. With new prognostic classifications, enhanced understanding of immunopathologic mechanisms, and novel treatment paradigms, clinical and experimental interest in PICG remains high.

ANCA positive crescentic glomerulonephritis outcome in a Central East European cohort: a retrospective study

BACKGROUND

The recently suggested distinct pathogenic pathways for myeloperoxidase (MPO) and proteinase 3 (PR3) anti-neutrophilic cytoplasmic antibodies (ANCA) associated vasculitis could result in different modes of presentation and outcome. Moreover, kidney outcome was related to a new histopathologic classification of pauci-immune glomerulonephritis. As reports were not always concordant, possible because differences in severity of organ lesions and ethnicity, we evaluated the outcome of a cohort of Central-East European patients with crescentic glomerulonephritis in relation with ANCA specificity and histopathological classification.

METHODS

Seventy-five patients were consecutively diagnosed by kidney biopsy (76 % MPO-ANCA specificity, 52 % crescentic) and followed for a median period of 3.2 years. Study end-points were response to therapy, end stage renal disease (ESRD) and death.

RESULTS

PR3-ANCA patients were younger, in higher proportion male and had higher Birmingham Vasculitis Activity Scores (BVAS). The kidney disease was severe at presentation (median creatinine 5 mg/dL; 27 % required temporary dialysis) and worst in PR3-ANCA positive patients (50 % patients needed temporary dialysis vs. 19 %). The lung was the second most affected organ (31 % severe lung hemorrhage). Lung and kidney damage were related; the odds of hemorrhagic alveolitis in patients needing dialysis at presentation were 4 (95 % CI 1-13; p = 0.006) times higher than in those who did not. The rate of response to therapy (without signs of active vasculitis and stable or declining serum creatinine) was 60 % and was associated with dialysis independency, older age and higher platelet number at presentation. The probabilities to survival 1 and 5 years for kidney and patient were 93 and 64 %, and respectively 88 and 67 %. Kidney survival was predicted by response to therapy and dialysis independency at presentation. Patients with BVAS < 15 and responding to induction therapy had better chances of survival. Neither response to therapy nor outcome was influenced by ANCA specificity or by the histopathological class.

CONCLUSIONS

When kidney damage is severe in ANCA vasculitis, the need of dialysis at presentation and the response to induction therapy overcome the prognostic utility of both ANCA specificity and histopathological class.

Twenty-five years of RENHIS: a history of histopathological studies within EUVAS

In the early 1990s, an international working group of experienced renal pathologists, the Renal Histology group, set up a scoring system for biopsies with anti-neutrophil cytoplasmic autoantibody (ANCA)-associated glomerulonephritis. This scoring system subdivided glomerular, interstitial and vascular lesions and served as a tool for the evaluation of all renal biopsies from studies of the European Vasculitis Study Group (EUVAS). Histopathological studies gave new insights into the prediction of renal outcome in patients with ANCA-associated glomerulonephritis. Percentage of normal glomeruli and a selected number of interstitial parameters were reliable predictors of long-term follow-up glomerular filtration rate in all studies. Out of these results, a histopathological classification distinguishing focal, crescentic, mixed and sclerotic classes of ANCA-associated glomerulonephritis was developed. Until today, 13 studies have validated this classification system. Future studies will try to determine if and how renal histology could be helpful in guiding treatment of ANCA-associated glomerulonephritis.