Routine monitoring of ANCA antibody levels should be implemented in AAV patients in remission as a means to determine their risk of relapse, according to Japanese researchers.
Their study, “Association between reappearance of myeloperoxidase-antineutrophil cytoplasmic antibody and relapse in antineutrophil cytoplasmic antibody-associated vasculitis: Subgroup analysis of nationwide prospective cohort studies,” was published in the journal Arthritis & Rheumatology.
Levels of antineutrophil cytoplasmic antibodies (ANCA) have been used in the clinic to diagnose AAV. While these antibodies usually drop to normal levels in patients who achieve remission, studies suggest that a rise in ANCA antibodies may be predictive of future disease relapse.
But these studies were heterogeneous, and whether monitoring the levels of ANCA could be used to predict disease relapse has been controversial.
Now, researchers analyzed data from two Japanese nationwide group studies to determine the usefulness of this testing. They focused on AAV patients with autoantibodies against the myeloperoxidase (MPO) protein.
The team included data from AAV patients who had achieved disease remission within six months of remission induction therapy. They used the Birmingham Vasculitis Activity Score (BVAS) 2003 to assess disease activity.
“Remission was defined as BVAS = 0 on two consecutive occasions at least one month apart, according to the European League against Rheumatism (EULAR) recommendations plus a daily dose of glucocorticoid of 15 mg of prednisolone (PSL) or less by month 6,” they wrote.
Among the 477 patients enrolled in the two studies, 271 were included in the analysis. Most patients were women and their median age was 73.
Also, 183 patients had microscopic polyangiitis, 34 were classified as having granulomatosis with polyangiitis, and 15 had eosinophilic granulomatosis with polyangiitis.
Most patients (72%) achieved normal MPO antibody levels within six months of induction therapy. However, by the 24th month, 40% of patients had a reappearance of these antibodies, which was associated with a subsequent or concomitant relapse.
“Reappearance of MPO-ANCA was more frequent in patients with relapse than in 75 age- and sex-matched control patients without relapse,” researchers wrote.
Indeed, after taking into account age, sex, AAV type, and BVAS score, patients who had a reappearance of MPO antibodies were found to be 26.2 times more likely to experience a relapse.
Overall, these findings suggest that routine monitoring of MPO antibody levels could be useful as a biomarker for predicting the risk of relapse in these patients.