Biologic Treatment Registry Across Canada (BioTRAC): a multicentre, prospective, observational study of patients treated with infliximab for ankylosing spondylitis

OBJECTIVES: To describe the profile of patients with ankylosing spondylitis (AS) treated with infliximab in Canadian routine care and to assess the effectiveness and safety of infliximab in real world. SETTING: 46 primary care rheumatology practices across Canada. PARTICIPANTS: 303 biological-naïve patients with AS or patients previously treated with a biological for <6 months and who were eligible for infliximab treatment as per routine care within the Biologic Treatment Registry Across Canada (BioTRAC). INTERVENTION: Not applicable (non-interventional study). PRIMARY AND SECONDARY OUTCOMES: Effectiveness was assessed with changes in disease parameters (AS Disease Activity Score (ASDAS), Bath AS Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI), Health Assessment Questionnaire Disease Index (HAQ-DI), physician global assessment of disease activity (MDGA), patient global disease activity (PtGA), back pain, C-reactive protein, erythrocyte sedimentation rate (ESR), morning stiffness). Safety was assessed with the incidence of adverse events (AEs). RESULTS: Of the 303 patients included, 44.6% were enrolled in 2005-2007 and 55.4% in 2008-2013. Patients enrolled in 2005-2007 had significantly higher MDGA and ESR at baseline while all other disease parameters examined were numerically higher with the exception of PtGA. Treatment with infliximab significantly (p<0.001) improved all disease parameters over time in both groups. At 6 months, 56% and 31% of patients achieved clinically important (change≥1.1) and major (change≥2.0) improvement in ASDAS, respectively; at 48 months, these proportions increased to 75% and 50%, respectively. Among patients unemployed due to disability at baseline, 12.1% returned to work (mean Kaplan-Meier (KM)-based time=38.8 months). The estimated retention rate at 12 and 24 months was 78.3% and 60.1%, respectively. The profile and incidence of AEs were comparable to data previously reported for tumour necrosis factor-α inhibitors. CONCLUSIONS: Characteristics of patients with AS at infliximab initiation changed over time towards lower disease activity and shorter disease duration. Infliximab treatment significantly reduced disease activity independent of treatment initiation year, although patients enrolled in recent years achieved lower disease activity over 48 months. TRIAL REGISTRATION NUMBER: NCT00741793.