Factors Associated With Relapses and Performance of the French Vasculitis Study Group Relapse Score in a Cohort of Mexican Patients With Antineutrophil Cytoplasmic Antibody–Associated Vasculitis

Relapses occur in 14% to 44% of patients with antineutrophil cytoplasm antibody-associated vasculitis (AAV). The French Vasculitis Study Group Relapse Score (FRS) was recently proposed to predict relapse risk. This study aimed to identify relapse-associated factors and evaluate the FRS performance in a Mexican cohort. We performed a medical records review study including patients with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) who were followed for ≥12 months at a Mexican tertiary care center. Demographic, clinical, laboratory, and treatment data were analyzed using descriptive statistics, survival analysis, and ROC curves. Among 147 patients (110 GPA, 37 MPA), the median age at diagnosis was 49 years (IQR: 36 to 59). Over a median follow-up of 93 months (IQR: 48 to 152), 90 patients (61%) relapsed. Cumulative relapse rates at 12, 24, 36, 48, and 60 months were 13.6%, 32.3%, 40.3%, 47.5%, and 58.0%, respectively. FRS scores of 1, 2, and 3 corresponded to median relapse-free survivals of 85, 68, and 33 months, with 5-year relapse risks of 40.5%, 48.4%, and 68.3%, respectively. Discrimination was significant (log-rank p < 0.0004). The C-statistic for FRS alone was 0.648 (95% CI: 0.586-0.710); for model 1 (adding cluster 4), 0.666 (95% CI: 0.605-0.728); and for model 2 (adding cluster 4 and rituximab as maintenance), 0.700 (95% CI: 0.643-0.757). An age cutoff of ≤50 years showed better accuracy (AUC: 0.67, p = 0.0006) for relapse prediction. In this cohort, relapses were frequent. Incorporating clinical clusters and rituximab therapy to the FRS may enhance its predictive performance.