Retention Rate and Efficacy of the Biosimilar CT-P13 Versus Reference Infliximab in Patients with Ankylosing Spondylitis: A Propensity Score–Matched Analysis from the Korean College of Rheumatology Biologics Registry

Background: Long-term, real-world data are required to support the use of CT-P13 in chronic conditions such as ankylosing spondylitis. However, real-world evidence may be influenced by selection bias, which can confound outcomes. The aim of the current analysis was to confirm the long-term comparability of CT-P13 and reference infliximab treatment in patients with ankylosing spondylitis, using propensity score matching to adjust for baseline differences between groups. Methods: A propensity score–matching analysis was conducted on data from patients with ankylosing spondylitis in the Korean College of Rheumatology Biologics registry who received CT-P13 or reference infliximab. Drug retention, reasons for biologic therapy changes or discontinuation, and efficacy parameters were analyzed overall and by treatment line with up to 4 years of follow-up. Adverse events were recorded for each treatment group. Results: Propensity score matching was effective in matching 124 CT-P13–treated and 124 reference infliximab-treated patients. Median treatment duration and drug retention were similar between CT-P13 and reference infliximab. Three-year retention rates (95% confidence interval [CI]) were 64.2% (53.5–73.0) for CT-P13 and 55.6% (42.9–66.6) for reference infliximab. Overall, 17.1% (CT-P13) and 29.3% (reference infliximab) of patients discontinued biologic therapy, and 20.0% (CT-P13) and 15.2% (reference infliximab) changed biologic therapy. Efficacy assessments were generally similar between groups; both treatments were well tolerated. Conclusions: Propensity score–matching analysis confirmed that CT-P13 treatment was not associated with significant differences in drug retention, treatment duration, most efficacy parameters, or safety versus reference infliximab in Korean patients with ankylosing spondylitis, building evidence for the long-term comparability of these treatments. Trial registration: ClinicalTrials.gov identifier: NCT01965132.