Treatment with Infliximab plus Methotrexate Improves Anemia in Patients with Rheumatoid Arthritis Independent of Improvement in Other Clinical Outcome Measures-A Pooled Analysis from Three Large, Multicenter, Double-Blind, Randomized Clinical Trials

Objective: To evaluate the effect of antitumor necrosis factor-alpha monoclonal antibody infliximab treatment on anemia in patients with rheumatoid arthritis (RA). Methods: Data from patients with RA who received infliximab or placebo in the multicenter, placebo-controlled, double-blind, randomized ATTRACT, ASPIRE, and START studies were included in this post-hoc, pooled analysis. Infliximab (3 to 10 mg/kg) was administered every 4 or 8 weeks, and all patients received stable doses of methotrexate (MTX). We determined the percentage of anemic patients (baseline hemoglobin level <12 g/dL) who had an increase from baseline in hemoglobin level greater than or equal to 1 or 2 g/dL or achieved normal hemoglobin level at week 22. The association of improvement in anemia with improvement in clinical parameters was also evaluated. Results: Among patients with anemia at baseline, infliximab plus MTX treatment produced a significantly greater mean (standard deviation) increase in hemoglobin level from baseline to week 22 (0.74 [1.12], P < 0.0001) than placebo plus MTX (0.30 [0.92]). Significantly (P < 0.001) greater proportions of anemic patients treated with infliximab plus MTX had either at least a 1 g/dL (40%) or at least a 2 g/dL (12%) increase in hemoglobin level from baseline to week 22 or achieved normal hemoglobin level (43%) when compared with placebo plus MTX (19, 5, and 28%, respectively). Greater improvement in hemoglobin level among infliximab plus MTX-treated patients was consistently observed across subgroups and in patients without clinical response (American College of Rheumatology 20% response criteria) at week 22. Multiple regression analysis indicated that the effect of infliximab plus MTX on anemia was independent of improvement in disease activity. Conclusion: Treatment with infliximab plus MTX significantly improved hemoglobin level among anemic RA patients when compared with treatment with placebo plus MTX, even after adjusting for improvement in disease activity.