OBJECTIVE: ANCA-associated vasculitis (AAV) is a relapsing-remitting disease, resulting in incremental tissue injury. The gold-standard relapse definition (Birmingham Vasculitis Activity Score, BVAS>0) is often missing or inaccurate in registry settings, leading to errors in ascertainment of this key outcome. We sought to create a computable phenotype (CP) to automate retrospective identification of relapse using real-world data in the research setting. METHODS: We studied 536 patients with AAV and >6 months follow-up recruited to the Rare Kidney Disease registry (a national longitudinal, multicentre cohort study). We followed five steps: (1) independent encounter adjudication using primary medical records to assign the ground truth, (2) selection of data elements (DEs), (3) CP development using multilevel regression modelling, (4) internal validation and (5) development of additional models to handle missingness. Cut-points were determined by maximising the F1-score. We developed a web application for CP implementation, which outputs an individualised probability of relapse. RESULTS: Development and validation datasets comprised 1209 and 377 encounters, respectively. After classifying encounters with diagnostic histopathology as relapse, we identified five key DEs; DE1: change in ANCA level, DE2: suggestive blood/urine tests, DE3: suggestive imaging, DE4: immunosuppression status, DE5: immunosuppression change. F1-score, sensitivity and specificity were 0.85 (95% CI 0.77 to 0.92), 0.89 (95% CI 0.80 to 0.99) and 0.96 (95% CI 0.93 to 0.99), respectively. Where DE5 was missing, DE2 plus either DE1/DE3 were required to match the accuracy of BVAS. CONCLUSIONS: This CP accurately quantifies the individualised probability of relapse in AAV retrospectively, using objective, readily accessible registry data. This framework could be leveraged for other outcomes and relapsing diseases.

• Keywords
• Classification, Epidemiology, Outcome Assessment, Health Care, Vasculitis,
• MeSH
• Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis * diagnosis   MeSH
• Adult MeSH
• Phenotype * MeSH
• Middle Aged MeSH
• Humans MeSH
• Longitudinal Studies MeSH
• Recurrence * MeSH
• Registries MeSH
• Retrospective Studies MeSH
• Aged MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Multicenter Study MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides are a group of diseases characterised by necrotizing inflammation of small vessels such as arterioles, venules, and capillaries. ANCA-associated vasculitides (AAV) are referred to as small vessel vasculitides. Three AAV subgroups, namely granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic GPA (EGPA), are defined according to clinical features. The most common disease with renal involvement in AAV is MPA Approximately 90% of patients with MPA have renal involvement. While this rate is 70-80% in GPA, less than half of EGPA patients have renal involvement. Untreated survival in AAVs is less than one year. With appropriate immunosuppressive therapy, the 5-year renal survival rate is 70-75%. Without therapy, the prognosis is poor but treatments, typically immunosuppressants, have improved survival, albeit with considerable morbidity from glucocorticoids and other immunosuppressive medications. Current challenges include improving the measures of disease activity and risk of relapse, uncertainty about optimal therapy duration and a need for targeted therapies with fewer adverse effects. In this review, we described the treatment of renal involvement in AAV in line with current studies.

• Keywords
• Anti-neutrophil cytoplasmic antibody, Eosinophilic GPA, Granulomatosis with polyangiitis, Microscopic polyangiitis,
• MeSH
• Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis * complications   drug therapy   MeSH
• Churg-Strauss Syndrome * drug therapy   MeSH
• Granulomatosis with Polyangiitis * complications   drug therapy   MeSH
• Immunosuppressive Agents therapeutic use   MeSH
• Humans MeSH
• Microscopic Polyangiitis * drug therapy   MeSH
• Kidney Diseases * drug therapy   MeSH
• Antibodies, Antineutrophil Cytoplasmic MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Immunosuppressive Agents MeSH
• Antibodies, Antineutrophil Cytoplasmic MeSH

Updated guidelines on the management of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) were released in 2021 by the American College of Rheumatology jointly with the Vasculitis Foundation and, subsequently, in 2022 by the European Alliance of Associations for Rheumatology. In addition, in 2021, the Kidney Disease: Improving Global Outcomes had released updated recommendations on the treatment of AAV with glomerulonephritis (AAV-GN). Kidney involvement is particularly relevant in microscopic polyangiitis and granulomatosis with polyangiitis, but is less frequent in eosinophilic granulomatosis with polyangiitis. The management of AAV-GN has been a focus for drug development and change over the past 10 years. Avoidance of progression to end-stage kidney disease (ESKD) or kidney failure is one of the main unmet needs in the management of AAV, with ESKD having a major impact on morbidity, health costs and mortality risk. Relevant changes in AAV-GN management are related to remission-induction treatment of patients with severe kidney disease, the use of glucocorticoids and avacopan, and remission-maintenance treatment. All the documents provide guidance in accordance with the evidence-based standard of care available at the time of their release. With our work we aim to (i) show the progress made and identify the differences between guidelines and recommendations, (ii) discuss the supporting rationale for those, and (iii) identify gaps in knowledge that could benefit from additional research and should be revised in subsequent updates.

• Keywords
• ANCA-associated vasculitis, glomerulonephritis, granulomatosis with polyangiitis, guidelines, microscopic polyangiitis,
• MeSH
• Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis * complications   drug therapy   MeSH
• Kidney Failure, Chronic * etiology   therapy   MeSH
• Churg-Strauss Syndrome * MeSH
• Glomerulonephritis * drug therapy   MeSH
• Granulomatosis with Polyangiitis * therapy   MeSH
• Humans MeSH
• Microscopic Polyangiitis * therapy   MeSH
• Antibodies, Antineutrophil Cytoplasmic MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Antibodies, Antineutrophil Cytoplasmic MeSH

OBJECTIVE: Following induction of remission with rituximab in anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) relapse rates are high, especially in patients with history of relapse. Relapses are associated with increased exposure to immunosuppressive medications, the accrual of damage and increased morbidity and mortality. The RITAZAREM trial compared the efficacy of repeat-dose rituximab to daily oral azathioprine for prevention of relapse in patients with relapsing AAV in whom remission was reinduced with rituximab. METHODS: RITAZAREM was an international randomised controlled, open-label, superiority trial that recruited 188 patients at the time of an AAV relapse from 29 centres in seven countries between April 2013 and November 2016. All patients received rituximab and glucocorticoids to reinduce remission. Patients achieving remission by 4 months were randomised to receive rituximab intravenously (1000 mg every 4 months, through month 20) (85 patients) or azathioprine (2 mg/kg/day, tapered after month 24) (85 patients) and followed for a minimum of 36 months. The primary outcome was time to disease relapse (either major or minor relapse). RESULTS: Rituximab was superior to azathioprine in preventing relapse: HR 0.41; 95% CI 0.27 to 0.61, p<0.001. 19/85 (22%) patients in the rituximab group and 31/85 (36%) in the azathioprine group experienced at least one serious adverse event during the treatment period. There were no differences in rates of hypogammaglobulinaemia or infection between groups. CONCLUSIONS: Following induction of remission with rituximab, fixed-interval, repeat-dose rituximab was superior to azathioprine for preventing disease relapse in patients with AAV with a prior history of relapse. TRIAL REGISTRATION NUMBER: NCT01697267; ClinicalTrials.gov identifier.

• Keywords
• B-lymphocytes, granulomatosis with polyangiitis, rituximab, systemic vasculitis, therapeutics,
• MeSH
• Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis * drug therapy   MeSH
• Azathioprine * therapeutic use   MeSH
• Cyclophosphamide therapeutic use   MeSH
• Immunosuppressive Agents therapeutic use   MeSH
• Remission Induction MeSH
• Humans MeSH
• Antibodies, Antineutrophil Cytoplasmic MeSH
• Recurrence MeSH
• Rituximab therapeutic use   MeSH
• Treatment Outcome MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Randomized Controlled Trial MeSH
• Names of Substances
• Azathioprine * MeSH
• Cyclophosphamide MeSH
• Immunosuppressive Agents MeSH
• Antibodies, Antineutrophil Cytoplasmic MeSH
• Rituximab MeSH

The specific B-cell depleting anti-CD20 monoclonal antibody rituximab (RTX) is effective in terms of the treatment of various immune-mediated glomerulopathies. The administration of RTX has been shown to be reliable and highly effective particularly in patients with ANCA-associated vasculitis, which is manifested predominantly with non-nephrotic proteinuria. Stable long-term B-cell depletion is usually readily attained in such patients using standard dosing regimens. However, in patients with nephrotic syndrome and non-selective proteinuria, the RTX pharmacokinetics is altered profoundly and RTX does not maintain high enough levels for a sufficiently long period, which may render RTX treatment ineffective. Since complement-derived cytotoxicity is one of the important modes of action of RTX, hypocomplementemia, frequently associated with systemic lupus erythematodes, may act to hamper the efficacy of RTX in the treatment of patients with lupus nephritis. This review provides a description of RTX pharmacokinetics and pharmacodynamics in several selected glomerulopathies, as well as the impact of proteinuria, anti-drug antibodies and other clinical variables on the clearance and volume of distribution of RTX. The impact of plasmapheresis and peritoneal dialysis on the clearance of RTX is also discussed in the paper. A review is provided of the potential association between pharmacokinetic and pharmacodynamic alterations in various kidney-affecting glomerular diseases, the sustainability of B-cell depletion and the clinical efficacy of RTX, with proposals for potential dosing implications. The role of therapeutic drug monitoring in treatment tailoring is also discussed, and various previously tested RTX dosing schedules are compared in terms of their clinical and laboratory treatment responses. Since alternative anti-CD20 molecules may prove effective in RTX unresponsive patients, their pharmacokinetics, pharmacodynamics and current role in the treatment of glomerulopathies are also mentioned.

• Keywords
• ANCA-associated vasculitis, lupus nephritis, membranous nephropathy, minimal change disease, obinutuzumab, ocrelizumab, ofatumumab, vedolizumab,
• MeSH
• Antigens, CD20 * MeSH
• Humans MeSH
• Antibodies, Monoclonal MeSH
• Kidney Diseases * MeSH
• Proteinuria MeSH
• Rituximab therapeutic use   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Antigens, CD20 * MeSH
• Antibodies, Monoclonal MeSH
• Rituximab MeSH