In ANCA-associated small vessel vasculitis, patients may present with life threatening rapid clinical decline due to single or multiple organ involvement, especially targeting kidney and lungs (1). The sooner the diagnosis is made, the sooner appropriate and efficacious therapy can be installed. In an ideal situation, patient-tailored therapy should be available, optimizing the risk/benefit ratio of treatment, especially since the burden of toxicity of the induction and maintenance agents of choice can be huge. In this view, duration of maintenance therapy is also important and both choices of specific agents as well as the duration of treatment may have implications for the risks of morbidity, mortality and the quality of life. Following the initial treatment phase, there are several known risk factors for relapse and poor long term prognosis. In this thesis, we go into these factors to improve the clinical management and outcome of ANCA-associated vasculitis
