Hydroxychloroquine as an add-on therapy for the induction therapy of MPO-AAV: a retrospective observational cohort study

Background The remission rate of myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV) patients who received standard induction therapy is far from satisfactory. Improving the remission rate of MPO-AAV patients is essential. Hydroxychloroquine (HCQ), one of the classic antimalarial drugs, has been widely used in various autoimmune rheumatic diseases. This retrospective observational cohort study is aimed to evaluate the efficacy and safety of HCQ during induction treatment for MPO-AAV. Methods The medical records of patients diagnosed with MPO-AAV at Xiangya Hospital, Central South University from January 2021 to September 2023 were collected. They were assigned to the HCQ group or control group according to whether they used HCQ. The patients included were screened by propensity score matching. To evaluate whether MPO-AAV patients benefited from HCQ, we compared the prognosis of the two groups. The adverse effects of HCQ during follow-up were recorded. Results The composition ratio of complete remission, response and treatment resistance between HCQ group and control group were different statistically (P = 0.021). There was no significant difference between the two groups in one-year renal survival (P = 0.789). The HCQ group had better one-year patient survival than the control group (P = 0.049). No serious adverse effects were documented in the HCQ group. Conclusions HCQ together with standard induction treatment may improve the remission rate of MPO-AAV patients, and HCQ has good safety in our study.