The primary outcome of the study was time to development of clinical arthritis in subjects in both treatment groups. Clinical arthritis was defined as swollen and tender joints observed by two independent, blinded investigators.
Researchers found that, compared with placebo, a single infusion of rituximab reduced the baseline risk of arthritis development by 55% at 12 months (hazard ratio [HR] 0.45, 95% confidence interval [CI] 0.15 to 1.32; P=0.15) and 53% at 18 months (HR 0.48, 95% CI 0.19 to 1.19). In total, 30 participants developed arthritis. At the point in the study when 25% of subjects had developed arthritis, rituximab treatment caused a delay in arthritis development of 12 months compared with placebo.