Risk of Relapse of Antineutrophil Cytoplasmic Antibody–Associated Vasculitis in a Randomized Controlled Trial of Plasma Exchange and Glucocorticoids

OBJECTIVE: Relapses of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis are important events that can cause organ dysfunction and reduce quality of life. Understanding the effects of the initial treatments for ANCA-associated vasculitis on the subsequent risk of relapse may help guide monitoring and treatment. METHODS: We performed a post hoc analysis of participants with severe ANCA-associated vasculitis enrolled in an international two-by-two factorial randomized controlled trial comparing the effects of plasma exchange (PLEX) to no PLEX and a regimen of reduced glucocorticoid exposure to a standard regimen. We estimated the effects of treatments on relapses of any severity using three competing risk time-to-event models adjusted for patient and disease characteristics and other treatments. Each model was adjusted for disease manifestations in different ways. RESULTS: Of 704 participants, 649 (92.2%) achieved remission and 147 (22.7%) experienced 204 relapses. The relapse rate was 10.3 (95% confidence interval [CI] 8.4-12.1) relapses per 100 patient-years. Neither the use of PLEX (subhazard ratio 0.91-0.94; 95% CIs range from 0.66 to 1.31) nor a glucocorticoid regimen (subhazard ratio 0.93-0.94; 95% CIs range from 0.67 to 1.35) appreciably changed the risk of relapse. Proteinase 3-ANCA and the presence of nonhemorrhagic respiratory manifestations of the disease at trial entry were associated with increased risks of relapse. Receiving dialysis at baseline and administration of oral cyclophosphamide as induction therapy were associated with lower risks of relapse. CONCLUSION: In patients with severe ANCA-associated vasculitis, relapses remain common; neither the use of PLEX nor an initial glucocorticoid tapering regimen impacted relapse risk.