Infliximab treatment for rheumatoid arthritis, with dose titration based on the Disease Activity Score: dose adjustments are common but not always sufficient to assure sustained benefit

Background: Randomised controlled trials have shown that treatment with anti-tumour necrosis factor (anti-TNF) agents is effective in refractory rheumatoid arthritis (RA). Objective: To determine the effectiveness of anti-TNF in a general unselected group of patients with refractory RA. Methods: 68 patients with active RA despite treatment with disease modifying antirheumatic drugs were studied during 12 infliximab infusions. Infliximab (3 mg/kg/infusion) was given every 8 or 6 weeks. Clinical efficacy was assessed by the Disease Activity Score (DAS) index (44 joints). Dose adjustments were based on residual disease activity (DAS score>2.4). The primary end points were the percentage of patients achieving good or moderate response by the EULAR response criteria and the proportion of patients requiring dose adjustment. Results: 20 (29%) patients discontinued treatment owing to side effects, early inefficacy, or other considerations. Among the patients who continued treatment, 27 (56%) and 32 (67%) were responders on the 6th and 12th infliximab infusion, respectively. In the same patients, disease activity gradually improved without modifications in the initial dosing in 10 (21%), whereas in 38 (79%) the dose of infliximab and/or methotrexate was increased. Intensification of treatment led to a significant decrease in the mean DAS score in this group (from 5.27 just before dose modification to 4.54 before the 12th infusion, p<0.002). The EULAR response category improved in only 10/38 (26%), however. Conclusions: In this initial observational study of patients with RA treated with recommended doses of infliximab, adjustments in treatment were common but not always sufficient to maintain adequate disease control. Longitudinal controlled trials are needed to define the optimal dose escalation in patients with suboptimal response.