Cost-effectiveness analysis of gene-based therapies for patients with spinal muscular atrophy type I in Australia

Introduction Spinal muscular atrophy (SMA) is an inherited neuromuscular disorder and regarded as one of the most frequent genetic causes of infant mortality. The aim of this study is to develop a cost-effectiveness analysis of AVXS-101 (Onasemnogene Abeparvovec/Zolgensma®) and nusinersen (Spinraza®) for SMA to inform decision-making on reimbursement policies in Australia. Methods A Markov model was developed with five health states to evaluate the costs and effects for patients with SMA Type I from a healthcare system perspective over a time-horizon of 100 years. The model parameters were based on clinical trials, parametric distributions, published literature, and Australian registries. One-way and probabilistic sensitivity analysis were performed to appraise the uncertainties of the parameters in the model. A threshold analysis was conducted to estimate the cost of AVXS-101 of being cost-effective. Results The incremental cost-effectiveness ratio (ICER) of AVXS-101 was $1,808,471 per quality-adjusted life year (QALY) and that of nusinersen was $2,772,798 per QALY, compared to standard of care, respectively. The ICER of AVXS-101 was $1,238,288 per QALY compared to nusinersen. The key drivers influencing on ICERs were costs of using treatments and utility values of sitting and walking independently. Conclusion Both nusinersen and AVXS-101 resulted in health benefits, but they were not cost-effective with a commonly used willingness-to-pay (WTP) threshold of $50,000 per QALY. Developing high-quality clinical data and exploring appropriate WTP thresholds are critical for decision-making on reimbursement policies in the treatment of rare diseases.