Histopathological subgrouping versus renal risk score for the prediction of end-stage renal disease in ANCA-associated vasculitis

The Improved Kidney Risk Score in ANCA-Associated Vasculitis for Clinical Practice and Trials

SIGNIFICANCE STATEMENT

Reliable prediction tools are needed to personalize treatment in ANCA-associated GN. More than 1500 patients were collated in an international longitudinal study to revise the ANCA kidney risk score. The score showed satisfactory performance, mimicking the original study (Harrell's C=0.779). In the development cohort of 959 patients, no additional parameters aiding the tool were detected, but replacing the GFR with creatinine identified an additional cutoff. The parameter interstitial fibrosis and tubular atrophy was modified to allow wider access, risk points were reweighted, and a fourth risk group was created, improving predictive ability (C=0.831). In the validation, the new model performed similarly well with excellent calibration and discrimination ( n =480, C=0.821). The revised score optimizes prognostication for clinical practice and trials.

BACKGROUND

Reliable prediction tools are needed to personalize treatment in ANCA-associated GN. A retrospective international longitudinal cohort was collated to revise the ANCA renal risk score.

METHODS

The primary end point was ESKD with patients censored at last follow-up. Cox proportional hazards were used to reweight risk factors. Kaplan-Meier curves, Harrell's C statistic, receiver operating characteristics, and calibration plots were used to assess model performance.

RESULTS

Of 1591 patients, 1439 were included in the final analyses, 2:1 randomly allocated per center to development and validation cohorts (52% male, median age 64 years). In the development cohort ( n =959), the ANCA renal risk score was validated and calibrated, and parameters were reinvestigated modifying interstitial fibrosis and tubular atrophy allowing semiquantitative reporting. An additional cutoff for kidney function (K) was identified, and serum creatinine replaced GFR (K0: <250 µ mol/L=0, K1: 250-450 µ mol/L=4, K2: >450 µ mol/L=11 points). The risk points for the percentage of normal glomeruli (N) and interstitial fibrosis and tubular atrophy (T) were reweighted (N0: >25%=0, N1: 10%-25%=4, N2: <10%=7, T0: none/mild or <25%=0, T1: ≥ mild-moderate or ≥25%=3 points), and four risk groups created: low (0-4 points), moderate (5-11), high (12-18), and very high (21). Discrimination was C=0.831, and the 3-year kidney survival was 96%, 79%, 54%, and 19%, respectively. The revised score performed similarly well in the validation cohort with excellent calibration and discrimination ( n =480, C=0.821).

CONCLUSIONS

The updated score optimizes clinicopathologic prognostication for clinical practice and trials.

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.

A modified renal risk score for Chinese patients with antineutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND

The renal risk score (RRS) is a useful tool to predict end-stage renal disease (ESRD) in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The current study aimed to validate the predictive performance of RRS and to further modify this model in Chinese AAV patients.

METHODS

Two hundred and seventy-two patients diagnosed with AAV confirmed by renal biopsies were retrospectively enrolled from a single center. The RRS was calculated based on 3 categorical variables, i.e., the proportion of normal glomeruli, the proportion of interstitial fibrosis and tubular atrophy (IF/TA), and eGFR at biopsy, classifying these patients into low-, medium-, and high-risk groups. In addition, a modified model was developed based on the RRS and was further validated in another independent cohort of 117 AAV patients. The predictive performance of each model was evaluated according to discrimination and calibration.

RESULTS

Patients were classified by the RRS into low- (26.5%), medium- (46.7%), and high-risk (26.8%) groups, with 120-month renal survival rates of 93.3%, 57.2%, and 18.4%, respectively (P < 0.001). The RRS showed good discrimination but less satisfactory calibration. Therefore, a modified model with improved discrimination and calibration was developed in Chinese AAV patients, with eGFR, proportion of normal glomeruli (both as continuous variables), and IF/TA (< 25%, 25-50%, > 50%) included. Internal and external validation of the modified model were performed. Finally, an online risk prediction tool was developed based on the modified model.

CONCLUSIONS

The RRS was an independent predictor of ESRD of AAV patients. The modified model could predict the probability of ESRD for AAV patients with improved performance in Chinese AAV patients.

Evaluation of a renal risk score for Japanese patients with ANCA-associated glomerulonephritis in a multi-center cohort study

Background

In patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis, prediction of renal survival should guide the choice of therapy, but a prediction of the histological classification has inconsistencies.

Objectives

To evaluate the usefulness of renal risk score (RRS) for Japanese patients with ANCA-associated glomerulonephritis (AAGN) and compare the prediction for end-stage renal disease (ESRD) between RRS and the histological classification.

Methods

We retrospectively analyzed 96 patients with AAGN who underwent a renal biopsy. Renal survival was categorized by RRS, and the histological classification was assessed separately. We compared the predictive values for RRS and the histological classification.

Results

The median observational period was 37.5 (interquartile range [IQR] 21.5-77.0) months. The median RRS point at the time of renal biopsy was 2 (IQR 0-7.8), and the patients were categorized into low- (n = 29), medium- (n = 43), and high-risk groups (n = 24) using RRS. As expected, the renal prognosis was the worst in the "high-risk" group and the best in the "low-risk" group. In the histological classification, the survival deteriorated progressively from "focal" (best) to "mixed," "crescentic," and "sclerotic" (worst) classes, different from the order in the original proposal for this system. Multivariable Cox regression analysis revealed that RRS was independently associated with ESRD. The difference in prediction for renal survival between RRS and the histological classification was not significant using area under receiver-operating-characteristic curves.

Conclusion

We evaluated the usefulness of RRS in Japanese patients with AAGN and found it a stable predictor of renal survival in such patients.

Urinary Matrix Metalloproteinase 7 Activated by Oxidative Stress Predicts Kidney Prognosis in Myeloperoxidase-Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

Aims: Effective and applicable predictors of end-stage kidney disease (ESKD) are needed for patients with myeloperoxidase-antineutrophil cytoplasmic antibody-associated vasculitis (MPO-AAV) and kidney involvement. We investigated whether urinary matrix metalloproteinase-7 (uMMP7) was associated with kidney injury severity and incident ESKD in MPO-AAV. Results: A prospective two-stage study was conducted in 150 patients with newly diagnosed MPO-AAV in two independent cohorts. uMMP7 was measured on the days of initial and repeat kidney biopsies. In stage I, a higher initial uMMP7 level was associated with a lower estimated glomerular filtration rate (eGFR), higher level of proteinuria, and greater extent of kidney pathologic lesions. This elevated uMMP7 protein level is activated and potentially derived from the enhanced kidney production induced by oxidative stress. In stage II, uMMP7 at initial biopsy was independently associated with the incidence of ESKD over 6 years. The higher uMMP7 group (vs. lower) had an adjusted hazard ratio of 3.79 (95% confidence interval [CI], 1.49-6.09) for ESKD in the test cohort. Findings were similar in the validation cohort. A combination of data from the two cohorts revealed that adding uMMP7 into clinical or clinicopathologic models significantly improved risk discrimination for future ESKD. Innovation: An elevated uMMP7 level in MPO-AAV was independently associated with severe kidney injury and incident ESKD. Conclusions: uMMP7 in MPO-AAV improves identification of patients at risk of ESKD and may enable early and optimized therapy to improve outcomes. Antioxid. Redox Signal. 37, 246-256.

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.

Assessment of Renal Risk Score and Histopathological Classification for Prediction of End-Stage Kidney Disease and Factors Associated With Change in eGFR After ANCA-Glomerulonephritis Diagnosis

Introduction

The “Renal Risk Score” (RRS) and the histopathological classification have been proposed to predict the risk of end-stage kidney disease (ESKD) in ANCA-associated glomerulonephritis (ANCA-GN). Besides, factors associated with kidney function recovery after ANCA-GN onset remain to be more extensively studied. In the present study, we analyzed the value of the RRS and of the histopathological classification for ESKD prediction. Next, we analyzed factors associated with eGFR change within the first 2 years following ANCA-GN diagnosis.

Materials and Methods

We included patients from the Maine–Anjou ANCA-associated vasculitis registry with at least 6 months of follow-up. The values of ANCA-GN, histopathological classification, and RRS, and the factors associated with eGFR variations between ANCA-GN diagnosis and 2 years of follow-up were assessed.

Results

The predictive values of the histopathological classification and RRS were analyzed in 123 patients. After a median follow-up of 42 months, 33.3% patients developed ESKD. The predictive value of RRS for ESKD was greater than that of the histopathological classification. Determinants of eGFR variation were assessed in 80/123 patients with complete eGFR measurement. The median eGFR increased from ANCA-GN diagnosis to month 6 and stabilized thereafter. The only factor associated with eGFR variation in our study was eGFR at ANCA-GN diagnosis, with higher eGFR at diagnosis being associated with eGFR loss (p<0.001).

Conclusion

The RRS has a better predictive value for ESKD than the histopathological classification. The main determinant of eGFR variation at 2 years was eGFR at ANCA-GN diagnosis. Thus, this study suggests that eGFR recovery is poorly predicted by histological damage at ANCA-GN diagnosis.

Meta-Analytical Accuracy of ANCA Renal Risk Score for Prediction of Renal Outcome in Patients With ANCA-Associated Glomerulonephritis

Background: To evaluate the diagnostic accuracy of antineutrophil cytoplasmic antibody (ANCA) renal risk score (ARRS) for prediction of renal outcome in patients with ANCA-associated glomerulonephritis (ANCA-GN).

Methods: We searched PubMed, EMBASE, Ovid, Web of Science, the Cochrane Library, and ClinicalTrials.gov for studies, which used ARRS to predict end-stage renal disease (ESRD) in patients with ANCA-GN. Two reviewers independently screened articles for inclusion, assessed the quality of studies with both an adapted Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. We calculated the combined patients with ESRD in the ARRS categories and presented the summary and individual estimates based on the ARRS categories. Then, the sensitivity, specificity, diagnostic odds ratio (DOR), positive/negative likelihood ratio, and the area under the receiver operating characteristic (AUROC) curves of the pooled data for ARRS were used to assess the accuracy of the “above the low-risk threshold” (ARRS ≥ 2) and “high-risk grade” (ARRS ≥ 8) for renal outcome of patients with ANCA-GN. The hierarchical summary ROC (HSROC) was used to verify the accuracy value. The clinical utility of ARRS was evaluated by the Fagan plot. Heterogeneity was explored using meta-regression and subgroup analysis.

Results: A total of 12 distinct cohorts from 11 articles involving 1,568 patients with ANCA-GN were analyzed. The cumulative patients with ESRD at the maximum follow-up of 60 months was 5% (95% CI: 0.02–0.07; p < 0.001) for ANCA-GN with low ARRS (0–1 points) and significantly increased to 22% (95% CI: 0.15–0.29; p < 0.001) medium ARRS (2–7 points). The combined cumulative patients with ESRD was 59% (95% CI: 0.49–0.69; p < 0.001) high ARRS (8–11 points). The pooled sensitivity of ARRS ≥ 2 in predicting ESRD was 98% with a specificity of 30% and a DOR of 15.08 and the mean AUROC value was 0.82. The pooled sensitivity of ARRS ≥ 8 in predicting ESRD was 58% with a specificity of 86% and a DOR of 7.59. The meta-regression and subgroup analysis indicated that variation in the geographic regions, study design, index risk, follow-up time, age of patient, publication year, and number of patient could be the potential sources of heterogeneity in the diagnosis of ARRS ≥ 8.

Conclusion: This meta-analysis emphasized the good performance of the ARRS score in predicting the renal outcome in patients with ANCA-GN. However, these findings should be verified by future large-scale prospective studies.

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.

Validation of the renal risk score for antineutrophil cytoplasmic antibody-associated glomerulonephritis in a Chinese population

INTRODUCTION

In 2018, a renal risk score of antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (AAGN) based on estimated glomerular filtration rate (eGFR), normal glomeruli, and tubular atrophy/interstitial fibrosis (TA/IF) was proposed to predict renal outcomes. We aimed to evaluate this renal risk score in a myeloperoxidase (MPO)-ANCA predominant population in Northeast China.

METHODS

We retrospectively analyzed the clinicopathologic data of 65 patients biopsy-proven from a Chinese medical center. Each patient was assessed by eGFR, normal glomeruli, and TA/IF, and the renal outcome was evaluated using the renal risk score.

RESULTS

In our study, 95.4% of patients were ANCA positive (78.5% MPO-ANCA positive and 16.9% proteinase 3-ANCA positive). The average follow-up period was 14.3 months. Thirty-four patients (52.3%) reached end-stage renal disease (ESRD). Based on the renal risk score, 8 (12.3%), 31 (47.7%), and 26 (40%) patients were divided into the low-risk, medium-risk, and high-risk groups, respectively. Kaplan-Meier survival curves revealed the high-risk group had worse renal outcomes than the low-risk group (p<0.01) and the medium-risk group (p<0.01), but the renal outcome did not differ between the low-risk and medium-risk groups (p>0.017). Similar results were obtained by the competitive survival analysis. The AUC for 3-year overall ESRD predictions was 0.845. In the regression analysis, the renal risk score was a favorable predictor for the development of ESRD (HR 3.13, 95%CI 1.58-6.19, p=0.001).

CONCLUSION

The renal risk score is a preferred index that can predict ESRD in Chinese AAGN patients, especially in the high-risk group with worse renal outcomes. Key Points • The eGFR and percentage of normal glomeruli were valuable predictors of renal outcome, whereas TA/IF was not. • We confirmed the renal risk score is a preferred index that can predict ESRD in Chinese AAGN patients. • Based on the renal risk score, the high-risk group had worse renal outcomes than the low-risk group and the medium-risk group.

Antineutrophil Cytoplasmic Antibody-Associated Vasculitis With Acute Kidney Injury: Short-Term Recovery Predicts Long-Term Outcome

Background

Kidney involvement is common in antineutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV). It tends to be aggressive, and in some patients, the kidney involvement may reach the criteria of acute kidney injury (AKI). Here, we aim to describe the clinical characteristics of these patients and find risk factors for poor outcomes.

Methods

Patients diagnosed with AAV in our hospital from February 2003 to February 2017 were included. Those who reached the KDIGO AKI criteria were reclassified according to the KDIGO AKI stage. The clinical features of these patients were analyzed. Also, according to the variation of serum creatinine 3 months after AKI episode, patients were further divided into two groups: patients whose serum creatinine (Scr) level at the third month decreased by 30% or more from the peak Scr level was classified into G1 and others were classified into G2. Long-term renal and survival outcomes of these patients were analyzed with a Cox model. The renal endpoint was reaching end-stage renal disease (ESRD), and the survival endpoint was death. Nomograms were built based on cox models.

Results

Of 141 AAV patients included, during the median follow-up period of 64.0 (IQR 34.8, 85.4) months, 36 (25.5%) patients reached renal endpoints, and 22 (15.6%) patients died. The median renal survival time was 35.9 (IQR 21.3, 72.6) months and the median survival time was 48.4 (IQR 26.8, 82.8) months. Multivariate analysis showed that poor recovery of Scr level at 90 days (P < 0.001, RR = 9.150, 95%CI 4.163-20.113), BVAS score (P = 0.014, RR = 1.110, 95% CI1.021-1.207), and AKI stage 3 (P = 0.012 RR = 3.116, 95%CI 1.278-7.598) were independent risk factors for renal endpoints; poor recovery of Scr level at 90 days (P = 0.010, RR = 3.264, 95%CI 1.326-8.035), BVAS score (P = 0.010, RR = 1.171, 95%CI 1.038-1.320) and age (P = 0.017, RR = 1.046, 95%CI 1.008-1.086) were independent risk factors for all-cause death. The c-index of nomograms is 0.830 for the renal outcome and 0.763 for the survival outcome.

Conclusion

KDIGO AKI stage 3 is the risk factor for ESRD in AAV patients with AKI. The BVAS score and level of kidney function recovery at 90 days are the independent risk factors for both ESRD and all-cause death and are of predictive value for the outcome.

Histopathologic and clinicopathologic classifications of antineutrophil cytoplasmic antibody-associated glomerulonephritis: a validation study in a Korean cohort

Background

Antineutrophil cytoplasmic antibodies (ANCA)-associated glomerulonephritis (AAGN) is a common cause of rapidly progressive glomerulonephritis and requires prompt and proper immunosuppressive therapy to improve renal prognosis. This study aimed to evaluate the predictive value of two different classifications for renal outcomes in Korean AAGN patients.

Methods

Ninety-two patients who were diagnosed with AAGN at two tertiary hospitals between 2004 and 2018 were retrospectively analyzed retrospectively. The histopathologic classification according to glomerular pathology and the clinicopathologic classification according to normal glomeruli ratio, degree of interstitial fibrosis/tubular atrophy, and baseline renal function were evaluated using the Cox proportional hazards model.

Results

Forty-five patients (48.9%) progressed to end-stage kidney disease (ESKD) during the observation period. The mean age was 61.0 ± 15.3 years, and most patients had myeloperoxidase-ANCA (93.5%). In the histopathologic classification, the best renal survival occurred in the focal class, whereas the sclerotic class had the worst renal survival (sclerotic class vs. focal class; adjusted hazard ratio [aHR], 5.05; 95% confidence interval [CI], 1.32–19.31; p = 0.018). The mixed class had intermediate renal outcomes (mixed class vs. focal class; aHR, 4.23; 95% CI, 1.23–14.58; p = 0.022). In the clinicopathologic classification, the high-risk group had poor renal outcomes compared with the low-risk group (aHR, 6.56; 95% CI, 1.25–34.26; p = 0.026), but renal outcomes did not differ between the low- and medium-risk groups.

Conclusion

In Korean AAGN patients, histopathologic and clinicopathologic classifications had predictive value for renal outcomes, especially in the sclerotic class or the high-risk group with higher risk of progression to ESKD despite treatment.