Early vs Delayed Belimumab: 15‑Year Cost‑Effectiveness Findings

A modeled economic evaluation of biologic-naive adults with clinically active systemic lupus erythematosus compared early (≤2 years of disease duration) versus delayed initiation of intravenous belimumab using a cost-utility framework.

Outcomes were estimated over a 15-year horizon as total direct medical costs and quality-adjusted life-years (QALYs), presented as incremental differences between the two timing strategies. The analysis also included payer-facing uncertainty assessments, including sensitivity and scenario analyses, to show how modeled value varied under alternative assumptions.

The approach was described as a state-transition Markov model with monthly cycles across the 15-year analytic horizon, with patients occupying one mutually exclusive health state at a time (Markov model health states). The health states were pretreatment, complete response, partial response, nonresponse, no treatment, and death, with death treated as an absorbing state. As reported, all patients entered the model in pretreatment and were simulated to transition into response categories after a 4-month induction period, followed by ongoing monthly transitions. The authors describe this structure as a way to translate differences in response trajectories into long-horizon QALYs and direct medical costs for early versus delayed initiation.

In the 15-year base-case analysis, the model estimated that early initiation was associated with an incremental gain of 0.30 QALYs and an incremental cost of −$126,337.12 per patient compared with delayed initiation (15-year base-case cost-utility results). Here, “incremental” refers to the difference calculated as early initiation minus delayed initiation in the modeled cohorts. On that basis, the authors classified early initiation as “dominant” in the base-case point estimate (more QALYs and lower costs), while also reporting uncertainty intervals that crossed 0 for both incremental QALYs and incremental costs. As presented, the base-case outputs favored earlier timing on modeled health benefit and modeled spending.

Uncertainty analyses were summarized with separate metrics rather than repeating the base-case point estimates (sensitivity and scenario analyses). In probabilistic sensitivity analysis, early initiation was favored in 81.3% of 10,000 simulations, and the mean incremental net monetary benefit (INMB) was $141,337.12 using a $50,000/QALY willingness-to-pay threshold. In deterministic one-way sensitivity analysis, the model was most sensitive to assumptions about time horizon, the SRI-4 response odds ratio, and discount rate for incremental net monetary benefit, indicating where results shifted most with parameter changes. Scenario analyses also reported that biosimilar price-reduction scenarios produced positive INMBs across the evaluated conditions, keeping the direction of net value favorable within those scenarios.

In discussing coverage and reimbursement, the authors noted that the modeled findings could have implications for timing-based access criteria and stated that they may warrant reconsideration of reimbursement criteria to better reflect long-term value. The discussion emphasizes that modeled savings and modest QALY gains were estimated over an extended horizon, and that probabilistic and scenario results were used to characterize how often early timing remained favored under joint uncertainty.

The authors present the analysis as input to formulary and reimbursement conversations because it explicitly compared early versus delayed initiation while tracking downstream costs and QALYs over many years.

Key Takeaways:

• In the model’s 15-year base case, early belimumab initiation was associated with higher QALYs and lower total costs than delayed initiation.
• Probabilistic analysis reported that early initiation was favored in a majority of simulations, with a positive mean INMB at the stated willingness-to-pay threshold.
• One-way sensitivity work identified time horizon, SRI-4 response odds ratio, and discount rate as key drivers, and biosimilar price-reduction scenarios were reported to remain positive on INMB.