[Dose adjustment in patients treated with infliximab in routine rheumatologic care in Germany. Results from the Biologics Register RABBIT]

OBJECTIVE: Data from international observational studies show that a considerable proportion of patients use higher dosages of infliximab (INF) than the usual 3 mg every 8 weeks used in Germany for treatment of rheumatoid arthritis. The Data are, however, inconsistent and vary between countries. Using data from the German Biologics Register RABBIT we investigated: (1) how dosage of INF develops during the first year of treatment in routine care, and (2) how dosage translates into clinical effectiveness. PATIENTS: We analysed data from 344 patients who started a treatment with INF at their inclusion into the register and who were observed for the subsequent 12 months. Mean dosage at 3 months (after the loading dose) was 3.2 mg/kg body weight/infusion and 3.3 mg/kg after 1 year. If we also consider shortening the infusion intervals, the mean dosages at the start and after 1 year were 4.0 mg/kg body weight every 8 weeks. RESULTS: Patients who were treated with low dosages of up to 3 mg/kg/8 weeks showed significantly less improvement (EULAR response) than those who were treated with higher dosages. CONCLUSIONS: The data show that German rheumatologists are aware of the high costs of treatment and try to use the lowest possible dosage. However, for a certain proportion of the patients this might be insufficient.