A Meta-Analysis and Cohort Study of Histopathologic and Clinical Outcomes in ANCA-Negative versus -Positive Vasculitis

ANCA Kidney Risk Score Performance in a German Cohort of Patients with Histologically Confirmed ANCA-Associated Renal Vasculitis

Key Points

The revised ANCA kidney risk score accurately predicts ESKD in patients with ANCA-associated vasculitis, with increasing risk associated with higher scores. ANCA kidney risk score performs well in this population, identifying new risk factors and showing similar effectiveness to the previous ANCA renal risk score.

Background

Predicting the outcome of ANCA-associated vasculitis is a difficult task. One of the most promising prognostic scores, the ANCA renal risk score, has recently been updated and renamed to ANCA kidney risk score (AKRiS). We wanted to test its performance in our population.

Methods

In total, 164 patients were included and categorized in subgroups analogous to that of both scores. Multivariable logistic regression analysis was applied to assess the risk of renal failure. In addition, baseline data and outcome were compared between the subgroups of each score to retrieve useful clinical information.

Results

Stratified by AKRiS category, the proportions of patients who developed ESKD at 36 months were 9.8%, 29.1%, 63.0%, and 83.3%, respectively (P < 0.001). Those belonging to the higher risk groups showed more pronounced proteinuria and anemia at diagnosis (P = 0.001, P < 0.001, respectively). Although our patients exhibited a more severe disease phenotype than those of ANCA renal risk score and AKRiS, both scores performed equally well: The Harrell C-index was similar (0.8381 versus 0.8337). Beyond that, we found differences and similarities in the risk associations between the subgroups of both scores and disease activity or patient outcome, with some of them being described for the first time. For example, there was a higher risk of renal failure with anemia but not with C-reactive protein and the Birmingham Vasculitis Activity Score and an increased incidence of relapsing disease in the lower risk categories of ANCA renal risk score.

Conclusions

Here, we present the first external AKRiS validation confirming the improved ESKD prediction of the revised score in our cohort. Furthermore, we highlighted associations between risk score categories and patient mortality or vasculitis relapse.

Kidney Biopsy and Immuno-Rheumatological Diseases: A Retrospective and Observational Study

Renal involvement is a common occurrence in patients with immuno-rheumatological diseases (IRDs). Several instances of glomerulonephritis (GN) occur in the setting of IRD and complicate the clinical course of an underlying condition. The aim of this study was to observe the spectrum of nephropathies according to age, kidney function, history of IRD at the time of biopsy, and histopathological kidney diagnosis. We evaluated data relating to 699 consecutive kidney native biopsies (female 52.1%) with a median age of 48 years (IQR 34-62) performed in adult patients collected over 15 years. The study population was divided into three groups: patients with kidney histological findings correlated to underlying IRD (Group 1), patients with kidney histological findings not correlated to underlying IRD (Group 2), and patients with kidney histological findings compatible with "de novo" IRD (absent in personal medical history) (Group 3). Kidney involvement related to IRD was found in 25.2% of patients. Group 1 was mostly represented by lupus nephritis (76.6%), with a younger age than Group 3 (p < 0.001) and by a higher percentage of females than other groups (p < 0.001). Group 3 was the most represented by microscopic polyangiitis (50.8%) when compared with the other two groups (p < 0.001). Acute nephritic syndrome (p < 0.001), acute kidney injury (AKI), and abnormal urinalysis (p < 0.001) were more represented in Group 3 than the other groups. In conclusion, IRDs are characterized by different clinical presentations and heterogeneous histological findings. Kidney biopsy remains fundamental to achieving the correct diagnosis and starting targeted therapy.