The Cost-Effectiveness of Early Versus Delayed Belimumab Treatment for Systemic Lupus Erythematosus

Objectives Belimumab is an approved biologic therapy for active, autoantibody-positive SLE that has been shown to reduce disease activity, flare frequency, and glucocorticoid use, thereby preventing organ damage.[1] It is typically reserved for refractory disease but emerging evidence suggests earlier initiation of belimumab may lead to higher response rates, greater achievement of remission or low disease activity, and further reduction in glucocortoid use.[2] This cost-utility analysis evaluates the economic and health impacts of early vs delayed belimumab initiation for biologic-naïve adult patients with clinically active SLE, comparing direct medical costs and quality-adjusted life-years (QALYs). Methods A Markov model was developed to simulate disease progression over 5 years with monthly cycles from the U.S. payer perspective. Costs included drug acquisition, hospitalizations, outpatient care, and emergency visits, updated to 2024 USD. Transition probabilities, Euro-QoL-5D utility values, and healthcare resource utilization were derived from a targeted literature review. Patients began in a pre-treatment state and transitioned monthly between 4 health states: complete response (assessed by SLE Responder Index-4; SRI-4), partial response, non-response (did not meet SRI-4 and experienced a flare or treatment-emergent adverse event), and death. Patients in the early group had higher disease activity (3-point higher SLEDAI-2K) and higher glucocorticoid use (10mg/day more prednisone) at baseline relative to the delayed group. Early belimumab was defined as initiation within 2 years of diagnosis and delayed initiation followed failure of standard immunosuppressants. Results Early belimumab initiation provided an additional 0.09 QALYs at a cost savings of USD$8,639.48 per patient relative to delayed belimumab, yielding a favorable incremental cost-effectiveness ratio (ICER) of −USD$93,092.98/QALY, making it the dominant strategy. Sensitivity analyses identified utility values, flare rates, and SRI-4 response rates as key drivers (Figure 1). Early belimumab retained dominance across most parameter variations, though cost-effectiveness was attenuated in parameter extremes favoring delayed initiation. Conclusion Early initiation of belimumab in biologic-naïve adults with clinically active SLE is both clinically and economically advantageous, offering greater health benefits at a lower cost compared to delayed initiation. These findings support timely adoption of belimumab in appropriate patients and highlight the need to reform reimbursement policies that delay access. As mounting evidence across immune-mediated diseases supports early biologic intervention as disease-modifying, frameworks must evolve to recognize treatment timing as a critical driver of long-term outcomes.[3] This model highlights the potential of early belimumab to reduce morbidity, mitigate irreversible organ damage, and generate sustained value for patients and health systems. References [1.] Urowitz M. Arthritis Care Res (Hoboken) 2022;74:1822-8. [2.] Zhao Y. Rheumatology (Oxford) 2025;64:106-16. [3.] Mease P. ACR Open Rheumatol 2025;7:e70019.