Eficiency of different doses of rituximab in rheumatoid arthritis.
OBJECTIVE
Evaluate the effectiveness, cost and safety of rituximab in patients with rheumatoid arthritis (RA) depending on the dose used.


MATERIAL AND METHODS
Retrospective observational study conducted on 52 patients with RA treated with at least one dose of rituximab for 135.3 patient-years were included. Three treatment groups were obtained: (G1) First course and following two 1g infusions separated by 15 days; (G2) First course 2 infusions of 1g followed by 2 infusions of 500mg; (G3) First course and followed by 2 infusions of 500mg separated by 15 days. Re-treatments were administered on-demand according to the clinical activity. The retention time (Log-Rank), retreats and adverse events rates (incidence rate ratio) and treatment costs per patient-month of rituximab were analysed by groups.


RESULTS
Group 2 showed a better cost-effectiveness ratio than group 1, as it was associated with a longer retention of rituximab (mean [95% CI] 65.7 [60.8 to 70.7] months vs 33.5 [22.7 to 44.3]; P<.001) and a lower rate of severe adverse events with only a slight increase in the rate of retreatment (courses/patient-year [95% CI] 1.66 [1.39 to 1.93] vs. 1.01 [0.69 to 1.34]; P=.005), and in the costs (median/patient-month, €484.89 vs. €473.45). Although group 3 was €41.20/patient-month cheaper than group 2, it was associated with a higher rate of re-treatments and shorter retention of rituximab (P<.001).


CONCLUSIONS
The use of full-dose rituximab at onset, followed by reduced doses in successive courses administered on-demand retreatment may be the most cost-effective option.