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Abstract: TH-PO603

Treatment, Relapse, and Complications of Myeloperoxidase (MPO) and PR3 ANCA-Associated Glomerulonephritis: Report from an Australian Centre

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Chau, Ken Wang Tat, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia
  • Khoo, Tien K., Griffith University, Gold Coast, Queensland, Australia
  • Lam, Alfred K., Griffith University, Gold Coast, Queensland, Australia
  • Ranganathan, Dwarakanathan, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia
Background

ANCA-associated vasculitis is a group of autoimmune vasculitides of unknown aetiology, with different phenotypic manifestations. Myeloperoxidase (MPO) and Proteinase 3 (PR3) have emerged as two main serological subtypes and growing evidence reported differences between their disease characteristics. We investigate the disease manifestation, progression and complications in patients with biopsy-confirmed ANCA-associated glomerulonephritis (AAGN).

Methods

This retrospective study was performed at the Royal Brisbane and Women’s Hospital, a major tertiary hospital with a population catchment of approximately 1,030,006 people in North Brisbane, Australia. Patients with pauci-immune glomerulonephritis confirmed on kidney biopsy between 1st January 2005 to 1st October 2021 were identified. Clinical data were collected via medical records.

Results

A total of 1,433 kidney biopsy results were reviewed. 80 cases of pauci-immune AAGNs were identified. Majority were MPO-positive AAGN (53/80), as opposed to PR3-positive disease (21/80). 5/80 were ANCA negative and 1/80 did not have ANCA serology available.
Pulmonary involvement rates in PR3 and MPO AAGN were similar at 29% (6/21) and 30% (16/53) respectively.
Majority patients (58/73) had induction treatment with cyclophosphamide. More patients on cyclophosphamide developed malignancy compared to the patients on alternative therapy (14% (8/58) vs 5% (1/22), p=0.43).
Approximately one in five (17/80) patients had a relapse over the study period. More relapses occurred in PR3 than MPO disease (38% (8/21) vs 13% (7/53), p=0.02). Most relapses (12/17 cases) occurred within 2 years of diagnosis. The longest time to relapse was 12 years.
Numerous AAGN cases developed deep vein thrombosis or pulmonary embolism (8/80). The risks were higher in PR3 compared to the MPO group (3/21 vs 4/53, RR 1.89).
Malignancy was common (16/80). No difference was observed between MPO and PR3 subgroups (21% vs 24%). 56% (9/16) of malignancies were diagnosed after AAGN diagnosis.

Conclusion

This is the first study in Australia that reports on AAGN outcomes and disease associations. Both, MPO and PR3 AAGN are associated with pulmonary involvement. PR3 AAGN is associated with a significantly higher relapse rate compared to MPO disease, this finding is consistent with other cohort studies in Europe.