Objectives To study the efficacy of rescue treatment strategies and outcomes in patients with Wegener's granulomatosis (WG) and microscopic polyangiitis (MPA) not achieving remission with first-line induction with corticosteroids (CS) and intravenous cyclophosphamide (CYC).

Methods 159 eligible patients in the Wegener's Granulomatosis-Entretien (WEGENT) trial newly diagnosed with systemic or renal WG or MPA with ≥1 poor prognosis factors were included in this prospective study. Rescue treatment strategies and outcomes in patients with induction-refractory disease were analysed and patient characteristics at diagnosis were compared with those of induction-responders.

Results Most patients (n=126, 79.2%) achieved remission; 1 stopped induction because of allergy and 32 were induction-refractory (24 WG and 8 MPA); 11 died rapidly within a median of 2.5 months, 6 of uncontrolled disease, 1 of an infectious complication and 4 of both. Treatment was discontinued in 1 patient with MPA with end-stage renal disease. Induction was switched to oral CYC in 20 patients, combined with infliximab in 1; 15 (75%) achieved remission or low disease activity state, 3 subsequently died of uncontrolled disease and 2 entered remission using several other agents including biological agents. Alveolar haemorrhage and a creatinine level >200 μmol/l were independently associated with induction-refractory disease. Among patients with induction-refractory disease, massive alveolar haemorrhage was associated with higher mortality.

Conclusion Switching to oral CYC can be an effective rescue treatment for patients with systemic forms of WG or MPA who fail to achieve remission with first-line CS and intravenous CYC. However, a more rapidly effective regimen remains to be identified for most severely affected patients whose outcomes can be rapidly fatal.