Association between longitudinal ANCA patterns and risk of clinical relapse
The proportion of patients who developed a clinical relapse was similar in patients with recurrent or persistent ANCA patterns (34/39; 87.2% vs. 15/21; 71.4%; p=0.13). These relapse rates were much higher than those observed in patients with monophasic or remitting ANCA patterns (6/29; 23.1% and 4/13; 30.8% respectively)(Table 2). Because of these similarities, in some analyses the four subsets were joined into two groups, the recurrent/persistent (R/P) pattern and the monophasic/remitting (M/R) pattern (Fig 1).
In the univariate analysis, other variables associated with an increased risk of clinical relapse were the diagnosis of GPA, the anti-PR3 specificity, the presence of arthritis, ENT or ocular involvement, and having received treatment with azathioprine, methotrexate or rituximab. Clinical features such as renal failure were associated with a lower risk of clinical relapse (Table 3).
In the multivariate Cox regression analysis, the recurrent or persistent ANCA patterns together with the presence of arthritis or ocular involvement, the absence of fever or having received rituximab treatment were independently associated with a higher risk of clinical relapse. Neither the clinical diagnosis, nor the antigenic specificity were associated with an increased risk of clinical relapse (Table 4).