Impact of Non-Fixed Versus 6 Month Fixed Retreatment Schedules on Serum Immunoglobulins Following Rituximab in Patients with Rheumatoid Arthritis

Results: The percentages of patients developing low IgG or IgM did not differ between groups after the 3rd cycle, but those with non-fixed retreatment tended to be higher. After 4 cycles, median IgM levels were significantly lower in both groups compared with pretreatment (p<0.05). Only patients in the fixed retreatment group receiving 4 cycles of treatment showed a significant drop in median IgG level (p<0.05). IgA levels remained within the normal range. Withdrawals due to infections per 100 patient years (py)s in patients with low IgG were higher after 3 Cycles in patients within the fixed retreatment group (4.60/100py vs 1.36/100py, CI: 0.59, 6.23). DAS28 did not differ between cohorts after multiple cycles.