Summary:
Introduction: long-term observation of patients with
ANCA-associated vasculitis (AAV) allows the identification of different
longitudinal patterns of ANCA levels during follow-up. This study aimed
to characterise these patterns and to determine their prognostic
significance.
Methods: all ANCA determinations performed in two university
hospitals along a 2-year period were retrospectively reviewed. Patients
were included in the analysis if they had high titers of
anti-myeloperoxidase (anti-MPO) or anti-proteinase 3 (anti-PR3)
antibodies at least once, they had ≥5 serial ANCA determinations, and
they had AAV diagnosed by biopsy or ACR classification criteria.
Patients’ time-course ANCA patterns were classified as monophasic,
remitting, recurrent or persistent. Associations between ANCA patterns
and prognostic variables (relapse rate and renal outcome) were analysed
by univariate and multivariate statistics.
Results: A total of 99 patients (55 with microscopic
polyangiitis [MPA], 36 with granulomatosis with polyangiitis
[GPA], and 8 with eosinophilic granulomatosis with polyangiitis)
were included. Median follow-up was 9 years. Among patients diagnosed
with MPA or GPA, recurrent or persistent ANCA patterns were associated
with a higher risk of clinical relapse (HR 3.7 [95% CI 1.5-9.1] and
HR 2.9 [95% CI 1.1-8.0] respectively), independently of clinical
diagnosis or ANCA specificity. In patients with anti-MPO antibodies, the
recurrent ANCA pattern was associated with worsening renal function (OR
5.7 [95% CI 1.2-26.0]).
Conclusion: Recurrent or persistent ANCA patterns are
associated with a higher risk of clinical relapse. A recurrent ANCA
pattern was associated with worsening renal function in
anti-MPO-associated vasculitis.