The effective threshold dose of etanercept in patients with methotrexate-resistant rheumatoid arthritis.

Introduction: The therapy of rheumatoid arthritis (RA) was advanced by biological agents, yet costly. This study aims to identify the effective threshold dose of etanercept (ENT) and cost-effectiveness in methotrexate (MTX)-resistant RA in real world.

Methods: Eligible patients had an inadequate response (DAS28-ESR > 3.2) to initial MTX monotherapy, and subsequently received etanercept. The effective cut-off value of cumulative dose was identified to maintain remission response (DAS28-ESR < 2.6) at month 24 by using restricted cubic splines. Remission rate, low disease activity (LDA) rate, glucocorticoid exposure, safety, and cost-effectiveness were compared between the saturated and non-saturated dose groups divided by the cut-off dose.

Results: Seventy-eight (14.2%) of 549 enrolled patients were eligible, and 72 patients completed follow-up. The 2-year cumulative cut-off dose that maintained remission response at 24 months was 1975 mg. And the recommended threshold dosing strategy of etanercept was twice weekly (BIW) for the first 6 months, every week (QW) for the next 6 months, and every 2 weeks (Q2W) and every month (QM) for the second year. Greater net changes in DAS28-ESR score were observed in the ENT saturated dose group than in the non-saturated dose group (average change 0.569, 95%CI 0.236-0.901, p = 0.001). The proportion of patients achieving remission (27.8% vs 72.2%, p < 0.001) and LDA (58.3% vs 83.3%, p = 0.020) in the non-saturated group was both significantly lower than that in the saturated group at 24 months. The incremental cost-effectiveness ratio of the saturated group referred to the non-saturated group was 5791.2 $/QALY.

Conclusions: In refractory RA patients, the effective cumulative cut-off dose of etanercept for sustained remission at 24 months was calculated as 1975 mg, and receiving saturated dose was more effective and cost-effective than with non-saturated dose. Key Points • The effective cumulative cut-off dose of etanercept for sustained remission at 24 months in RA patients is calculated as 1975 mg. • Receiving saturated dose of etanercept is more effective and cost-effective than with non-saturated dose in refractory RA patients.