Relapse in Anti-Neutrophil Cytoplasm Antibody (ANCA)-Associated Vasculitis.

Clinical relapses are common in anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis, necessitating repeated treatment with immunosuppressive therapy, and increasing the risks of severe adverse events. Better understanding the basis of relapse would help stratify patients, testing the notion that more treatment may prevent development of relapse, whereas in those at low risk of disease flares, treatment minimization may be appropriate, reducing risks of adverse events, most notably infectious complications and drug toxicity. However, relapse can only occur following remission, and although defining clinical remission may seem straightforward, there is evidence in many remission patients of persistent inflammatory and immunological activity, at levels above those found in healthy individuals. This suggests that we may not truly be achieving disease remission in many patients and these persistent responses may set the patient up for subsequent disease flares. Understanding the underlying pathophysiological basis of disease activity and remission is paramount to help define better biomarkers of relapse, which should positively affect adverse events and patient outcomes.