OBJECTIVES: Rituximab and its biosimilars are considered the first treatment for active rheumatoid arthritis (RA) with high disease activity despite at least 3 conventional disease-modifying antirheumatic drugs (DMARDs) in Thailand. The annual direct medical costs of rituximab seem to be lower than other biologic DMARDs. This option contrasts the recommendations in other countries, as tumor necrosis factor inhibitors (TNFi) are the first treatment. This study aims to assess the cost-effectiveness and budget impact of TNFi and biosimilars compared to rituximab and its biosimilar.

METHODS: A Markov model was employed to estimate lifetime societal costs, life years (LY), and quality-adjusted life years (QALY) for RA patients with Disease Activity Score of 28-erythrocyte sedimentation rate > 5.1. We compare the effectiveness of six TNFi (etanercept, infliximab, golimumab, two infliximab biosimilars; Remsima® and Ixifi®, and an adalimumab biosimilar: Amgevita®) with rituximab or its biosimilar, Truxima®. Efficacy data were sourced from a systematic review, network meta-analysis, and existing literature. Costs and health outcomes were discounted at an annual rate of 3% (2022 values). The incremental cost-effectiveness ratio (ICER) was calculated against a threshold of 160,000 THB (4,634 USD) per QALY gained. Probabilistic and one-way sensitivity analyses are conducted to assess parameter uncertainties.

RESULTS: All TNFi options yielded comparable LY and QALY to rituximab. While etanercept incurred higher costs and inferior health outcomes, golimumab was not cost-effective despite improved QALY. In contrast, infliximab and its biosimilars exhibited lower costs and comparable outcomes. Adalimumab biosimilar was the only TNFi considered cost-saving with superior outcomes compared to RTX biosimilar. Potential savings from using adalimumab biosimilar over rituximab could range from 12 to 221 million THB per year.

CONCLUSIONS: For RA patients with high disease activity eligible to a biologic DMARDs in Thailand, adalimumab biosimilar should be considered the first option over rituximab, regarding the potential budget savings and enhanced patient outcomes.