Treatment outcomes in ANCA-associated vasculitis:Determinants of efficacy and toxicity

In the last 50 years, ANCA-associated vasculitis changed from a lethal disease to a chronic disease with a much better life expectancy. This has led to new challenges in its treatment. For example, patients still experience frequent relapses of vasculitis, resulting in damage from disease activity and adverse effects of treatment. As a result, patients experience limitations in daily activities, even after successful treatment. A personalised treatment might improve the balance between efficacy and toxicity of treatment. In this thesis, we show that several genes affect efficacy and toxicity of drugs used for vasculitis. If this knowledge is expanded on in independent research, we will be closer to a personalised treatment.We have shown that classification based on ANCA type is important, although some geographical differences cannot be explained by ANCA type alone. Patients receiving azathioprine maintenance therapy have an increased risk of developing hypersensitivity for this drug than previously assumed. Its symptoms strongly resemble an infection or disease relapse. It is important to be aware of this adverse effect, since it can simply be treated by stopping and replacing azathioprine. Lastly, it is important to study a rehabilitation or training programme to improve daily functioning. Because every vasculitis patient is unique, among other reasons because of differences in organ involvement, the individual patient should be considered instead of developing one training programme for all vasculitis patients