EFFICACY OF INFLIXIMAB IN RHEUMATOID ARTHRITIS: A RELATIONSHIP TO THE TOTAL DOSE OF THE DRUG

Objective: to analyze the relationship of the clinical and antidestructive effect of infliximab (INF) to its total dose in patients with rheumatoid arthritis (RA).Subjects and methods. A one-year investigation included 135 patients with RA. All patients received INF 3 mg/kg at weeks 0, 2, 4 and then every 8 weeks. During each visit, the number of tender and swollen joints, C-reactive protein level, and erythrocyte sedimentation rate were determined and the Health Assessment Questionnaire (HAQ) was filled out. DAS-28 changes were used to assess therapeutic effect of INF. Joint destruction was evaluated by the Sharp method modified by van der Heijde. All patients were examined according to the protocol before each INF infusion. The result of INF therapy was assessed at week 54 in all patients (including in those who had not completed a one-year INF therapy cycle). According to the total dose of INF, the patients were divided into three groups: 1) ≤4 infusions (low-dose, n = 63); 2) 5–7 infusions (medium-dose, n = 31); 3) ≥8 infusions (full-dose, n = 41). Group 1 received an average of 2.5 IFN infusions; Group 2 and 3 – 5.8 and 8.8 infusions, respectively.Results. Baseline high disease activity (DAS28 > 5.1) was noted in the majority of the patients: 69% in Group 1, 86.6% in Group 2, and 62.1% in Group 3. All the patients showed a prompt (just at 14 weeks of treatment) and significant (p < 0.05) decrease of RA activity. This reduction remained significant at week 54. By the end of follow-up there were more patients with low disease activity (including those with DAS28 remission) in Group 3 than the other groups (53.9% versus 27.3 and 50% in Groups 1 and 2, respectively). After the completion of therapy, the highest percentage of patients with high disease activity was seen in Group 1 (36.4%). The number of remissions was comparable in Groups 2 and 3 (28.6 and 23.1%, respectively) and smaller in Group 1 (18.2%). Significantly more obvious radiographic disease progression was noted in Group 1 than in the two other groups.Conclusion. The lower total dose of INF can cause a long-lasting clinical effect in some patients with RA, but it does not substantially suppress joint destruction. There were no significant differences between patients receiving medium and full doses of this drug in and the degree of radiographic disease progression.