Rituximab in rheumatoid arthritis. Phase IIa: American College of Rheumatology (ACR) responses at 48 weeks (NRI). *P < 0.0001; †P = 0.003; ‡P = 0.03; §P = 0.01; P values using Fisher's exact test, comparing MTX with each RTX group. CTX, cyclophosphamide; MTX, methotrexate; NRI, nonresponder imputation; RTX, rituximab. With permission from Edwards and coworkers . Copyright © 2004 Massachusetts Medical Society. All rights reserved.