Long-term outcomes of patients with propylthiouracil-induced anti-neutrophil cytoplasmic auto-antibody-associated vasculitis

Objective. It was well known that propylthiouracil (PTU) could induce ANCA-associated vasculitis (AAV) and clinical evident vasculitis could resolve after cessation of PTU with or without immunosuppressive therapy. However, the treatment strategy for patients with PTU-induced AAV remained inconclusive and their long-term outcomes were lacking. The aim of our study was to summarize these data. Methods.Fifteen patients with PTU-induced AAV, receiving immunosuppressive agents for <12 months and following over 24 months, were selected in the current study. The clinical and pathological data, including treatment protocols and outcomes, were retrospectively investigated. Results. All the patients were followed for a mean of 55.0 (25-98) months. PTU was discontinued upon diagnosis of PTU-induced AAV. Immunosuppressive therapy was administrated only for patients with vital organ involvements, such as lung and kidney, and lasted only 7.9 +/- 3.3 (0.27-12) months. No relapse of vasculitis occurred during follow-up, even after withdrawal of immunosuppressive therapy. Twelve (80%) patients remained in complete remission and one patient remained in partial remission at the latest follow-up. Two patients were treatment resistant due to late referral and late withdrawal of PTU, both of them progressed to end-stage renal disease. For uncontrolled hyperthyroidism on presentation, six patients switched to methimazole and none of them experienced relapse of vasculitis. Conclusions. The long-term outcomes of patients with PTU-induced AAV were relatively good. PTU should be discontinued immediately after diagnosis. Immunosuppressive therapy may be only used in patients with vital organ involvements, and a long-term maintenance therapy may not be necessary.