Objectives: Rituximab (RTX) is a key treatment for ANCA-associated vasculitis (AAV), but RTX-induced acute thrombocytopenia (RIAT) remains a concern. We aimed to evaluate the risk and risk factors of RIAT in patients with AAV undergoing RTX induction therapy.
Methods: Patients with new-onset microscopic polyangiitis or granulomatosis with polyangiitis who received RTX in a nationwide multicentre registry in Japan were included. RIAT was defined by platelet count reductions within 28 days post-RTX. Risk factors for RIAT were identified by using logistic regression with stepwise selection, and prediction models were developed. Model performance was assessed using C-statistics.
Results: Among 175 patients with AAV receiving RTX, RIAT occurred in 35.4% of them. Diabetes mellitus (odds ratio [OR] = 4.96), cardiac disease (OR = 3.57), low platelet count (OR = 1.04 per 104/μl decrease), increased serum creatinine (OR = 1.44 per 1 mg/dl increase), low albumin (OR = 2.33 per 1 g/dl decrease), and high KL-6 (OR = 1.09 per 100 U/ml increase) were identified as significant predictors. A predictive model incorporating these factors achieved a C-statistic of 0.817.
Conclusion: RIAT is a frequent complication of RTX induction in patients with AAV, with diabetes mellitus and cardiac disease being strong risk factors. Our predictive model enables risk assessment for RIAT, allowing clinicians to optimize treatment strategies.
Keywords: ANCA-associated vasculitis; cardiac disease; diabetes mellitus; predictive model; rituximab; thrombocytopenia.
© The Author(s) 2025. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.