Early Intervention With Biosimilars Compared With Leflunomide in Established Rheumatoid Arthritis: A Cost-Effectiveness Analysis in Hong Kong

OBJECTIVES: Among patients with rheumatoid arthritis (RA) who had inadequate response or intolerance to methotrexate, leflunomide is frequently recommended before biological disease-modifying antirheumatic drugs (bDMARDs), as the incremental monetary cost of using bDMARDs outweighs the improved clinical efficacy it provides. Biosimilar DMARDs share comparable efficacy and safety to the reference biologics with a 50 - 80% price reduction, providing an opportunity for early use of bDMARDs. We aim to evaluate the cost-effectiveness of biosimilar DMARDs versus leflunomide to inform formulary listing decisions for biosimilars.

METHODS: From an institutional perspective in Hong Kong, a Markov disease transition model was developed to simulate the lifetime disease progression of patients with RA who failed with methotrexate. The model contains three competing treatments: biosimilar infliximab (CT-P13), biosimilar adalimumab (ABP-501), and leflunomide. Model inputs were sourced from local population-based electronic health records databases, landmark clinical trials, and meta-analyses. Probabilistic and deterministic sensitivity analyses were conducted to address parameter uncertainties.

RESULTS: The lifetime healthcare cost and quality-adjusted life years (QALYs) for leflunomide, CT-P13, and ABP-501 are USD 118,316, 11.63; USD 113,850, 12.00; USD 107,311, 12.16, respectively. Both biosimilars demonstrated lower costs and greater QALYs compared to leflunomide. CT-P13 is associated with greater healthcare cost (USD 6539) but lower QALY gain (-0.16) compared to ABP-501. At the willingness-to-pay threshold USD 48,555/QALY gain (local GDP per capita in 2022 year), the probability of leflunomide, CT-P13, and ABP-501 being cost-effective out of 2,000 iterations was 0%, 10%, and 90%.

CONCLUSIONS: Biosimilar DMARDs are likely to be the cost-effective alternatives to leflunomide in the management of patients with RA who failed initial methotrexate treatment in Hong Kong. Local reimbursement agencies should give full consideration to the early use of biosimilars given the fact that none of the reference bDMARDs are reimbursed at present.