Effectiveness and safety of infliximab in rheumatoid arthritis: analysis from a Canadian multicenter prospective observational registry

Objective: To describe the profile of rheumatoid arthritis (RA) patients treated with infliximab in Canadian routine care and to assess the real-world effectiveness and safety of infliximab.

Methods: Biologics-naive RA patients from the Biologic Treatment Registry Across Canada were stratified based on their enrollment year. Effectiveness was assessed with the changes in clinical/laboratory parameters and patient-reported outcomes and the achievement of minimal disease activity and remission. Safety was assessed with the incidence of treatment-emergent adverse events (AEs).

Results: Among 628 patients, 45.9%, 34.6%, and 19.6% were enrolled between 2002-2005, 2005-2008, and 2008-2011, respectively. Patients recruited in more recent years had significantly lower Disease Activity Score with a 28-joint count using the C-reactive protein level (DAS28-CRP), Simplified Disease Activity Index (SDAI), Clinical Disease Activity Index (CDAI), swollen joint count in 28 joints, tender joint count in 28 joints, physician's global assessment of disease activity, patient's global assessment of disease activity, Health Assessment Questionnaire disability index, pain, erythrocyte sedimentation rate, and CRP level (P < 0.01 for all). Patient management also changed with a trend to initiate infliximab after failure of fewer disease-modifying antirheumatic drugs (DMARDs). Six-month treatment with infliximab resulted in statistically significant and clinically important improvements in all disease parameters examined, which were sustained over 36 months. The cumulative probability of achieving remission by 36 months, as defined by the DAS28, SDAI, and CDAI, was 56.2 (95% confidence interval [95% CI] 47.8-64.8), 31.0 (95% CI 23.8-39.8), and 36.2 (95% CI 28.5-45.3), respectively, which was significantly greater in patients with lower baseline disease activity. The profile and incidence of AEs were comparable to data previously reported for tumor necrosis factor α inhibitors.

Conclusion: RA patient characteristics at infliximab initiation changed over time toward lower disease activity. Furthermore, a trend to treat patients with fewer DMARDs before initiation of infliximab was observed. However, treatment with infliximab was effective in significantly reducing disease activity independent of the treatment initiation year.