Abstract 2023: Comparison of Predictors of Relapse in ANCA Vasculitis in 2 Independent Cohorts
Phil Seo
Authors
Christian Pagnoux1, Hyunsook Chin2, Susan L. Hogan2, Loïc Guillevin1, Ronald J. Falk2, Patrick H. Nachman2.
Purpose
After an initial diagnosis of Wegener’s granulomatosis, some—but not all—patients will experience disease relapse. Determining which patients are at the highest risk of relapse is crucial, since it would allow us to determine who stands to benefit most from prolonged immunosuppression. The purpose of this study was to examine the ability of certain risk factors to predict relapse among patient cohorts in the United States and in France.
Methods
Both the American and French groups maintained prospective inception cohorts comprised of patients with microscopic polyangiitis, Wegener’s granulomatosis, and renal-limited vasculitis. Hazard ratios were calculated using a multivariate analysis that controlled for age, gender, race, baseline serum creatinine, and cyclophosphamide exposure.
Results
Together, the cohorts had collected prospective data on 784 patients with ANCA associated vasculitis; the two patient groups had comparable distributions in terms of age, gender, and race. In both cohorts, the presence of PR3-ANCA or a history of pulmonary involvement was associated with an elevated hazard ratio for flare. PR3-ANCA positivity was associated with a hazard ratio of 1.87 (95% CI: 1.11, 3.14; P=0.022) in the American cohort, and a hazard ratio of 1.46 (95% CI: 1.03, 2.09; P=0.035) in the French cohort. Similarly, the presence of lung involvement was associated with a hazard ratio of 1.71 (95% CI 1.04, 2.81; P=0.034) in the American cohort, and 1.46 (95% CI 1.02-1.95) the French cohort. Disparate findings were reported for upper respiratory tract involvement. The American cohort reported a positive association, with a hazard ratio of 1.73 (95% CI 1.04-2.88, P=0.030), while the French cohort demonstrated a hazard ratio of 1.00 (95% CI: 0.69, 1.46; P=0.981).
Conclusions
Both PR3-ANCA and pulmonary involvement are independently associated with an increased risk of disease flare among patients with Wegener’s granulomatosis, microscopic polyangiitis, or renal-limited vasculitis.
Editorial Comment
This abstract provides further evidence that patients with PR3-ANCA (or C-ANCA) form a distinct subset of the ANCA-associated vasculitides and may behave differently from patients with other forms of this disease. Anecdotally, patients with PR3-ANCA positivity are more likely to have fulminant disease; this data implies that they are also more likely to suffer disease relapse. The strength of this cohort is that patients included in this analysis were followed since the time of diagnosis; in many cohorts, the length of disease activity prior to inclusion is unclear, making treatment history an important, unmeasured variable. Given how comparable the cohorts seem to be, it would have been interesting to see the results of a pooled analysis. The discrepancy in hazard ratios reported for upper respiratory tract disease raises an important question regarding disease state definitions: PR3-ANCA status is easy to assess; differentiating between an upper respiratory tract infection and Wegener’s granulomatosis is not, and may have lead to the differences seen in this study.
