Eficiency of different doses of rituximab in rheumatoid arthritis

Abstract

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.

Keywords: Adult; Adulto; Agentes antirreumáticos/administración y dosis; Agentes antirreumáticos/efectos adversos; Agentes antirreumáticos/uso terapéutico; Antibodies, monoclonal, murine-derived; Antibodies, monoclonal/administration and dosage; Antibodies, monoclonal/adverse effects; Antibodies, monoclonal/therapeutic use; Anticuerpos, monoclonal, derivado-murino; Anticuerpos, monoclonal/administración y dosis; Anticuerpos, monoclonal/efectos adversos; Anticuerpos, monoclonal/uso terapéutico; Antirheumatic agents/administration and dosage; Antirheumatic agents/adverse effects; Antirheumatic agents/therapeutic use; Arthritis, rheumatoid/drug therapy; Arthritis, rheumatoid/immunology; Artritis, reumatoide/inmunología; Artritis, reumatoide/terapia farmacológica; Dose-response relationship, drug; Drug administration schedule; Humanos; Humans; Pauta administración fármaco; Relación dosis-respuesta, fármaco; Rituximab; Tratamiento desenlace; Treatment outcome.