The French Vasculitis Study Group Relapse Score (FRS) may be a useful diagnostic tool for assessing the relapse risk in patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA), both types of antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV), according to a study published in RMD Open.
The study authors obtained patient and disease characteristics at diagnosis as well as long-term follow-up data from 5 consecutive prospective trials conducted by the French Vasculitis Study Group. They analyzed the data of 203 patients with GPA and 224 patients with MPA.
The patient characteristics at diagnosis were entered into a competing-risks model, with relapse as the event of interest and death as the competing event. The researchers statistically analyzed the data using univariate and multivariate analyses, identified the variables associated with relapse, and constructed a score. The score was then validated in an independent cohort of 209 patients with GPA or MPA.
According to the results, 207 (48.5%) patients experienced at least 1 relapse during the mean follow-up duration of 80.6±51.3 months. The risk of relapse was associated with proteinase 3 positivity, age of at least 75 years, and estimated glomerular filtration rate of at least 30 mL/min/1.73 m² at diagnosis.
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Furthermore, the FRS was based on 3 variables and ranged from 0 to 3 points: 1 point each for proteinase 3-ANCA positivity, estimated glomerular filtration rate of at least 30 mL/min/1.73 m², and age of at least 75 years. A higher FRS may show a greater risk of relapse: a score of 0 indicates a very low relapse risk, a 1 indicates a moderate relapse risk, and a FRS of 2 or 3 suggests a high relapse risk.
The validation analysis showed the 5-year relapse risk for an FRS of 0 was 8%, 30% for 1, 48% for 2, and 76% for 3.
“Estimation of the risk of relapse in the subgroup of MPA or GPA patients in the validation cohort showed that for the same FRS, the risk of relapse was higher in GPA than in MPA, although the confidence interval was wide due to the small number of patients, and remained significantly predictive of relapse in both vasculitides, ” Samson and colleagues highlighted.
“After 5 years of follow-up, none of the GPA patients with an FRS of 0 points had relapsed, 3/4 of those with an FRS of 3 points had relapsed, and about 1 in 2 patients with an initial intermediate FRS (1 or 2 points) had relapsed.”
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Most patients with GPA or MPA receive glucocorticoids and cyclophosphamide or rituximab as maintenance treatment. However, relapse occurs in 13.7% to 44% of patients after 18 to 36 months, and there are no reliable relapse predictive indicators. This score, if evaluated and validated in future prospective trials, may help clinicians tailor the duration of maintenance therapy for patients with AAV.
“In any case, it will be necessary to validate the FRS in a larger and more recent cohort of patients, in whom rituximab is the main used agent for induction and maintenance, as per current guidelines,” the study authors concluded.
Samson M, Devilliers H, Thietart S, et al. Score to assess the probability of relapse in granulomatosis with polyangiitis and microscopic polyangiitis. RMD Open. Published online March 27, 2023. doi:10.1136/rmdopen-2022-002953.