The study offers the first de novo cost-effectiveness model of these patients in the United States, according to the researchers.
A study assessing the cost effectiveness of nusinersen (Spinraza)—approved in December 2016—compared with best supportive care (BSC) in patients with infantile-onset spinal muscular atrophy (SMA), found that the disease-modifying therapy exceeded traditional cost-effectiveness thresholds.
The study offers the first de novo cost-effectiveness model of these patients in the United States, according to the researchers, who found that at its current price, nusinersen did not fall below the $990,000 quality-adjusted life year (QALY) gained in any analyses performed in the study.
Based on the analyses, which took into account survival, costs, utilities, and whether motor function milestones were sustained over lifetime, the base-case incremental cost-effectiveness results were more than $1.1 million per QALY and nearly $600,000 per life year (LY) compared with BSC.
“The results were most sensitive to the length of survival, the costs associated with treating people with SMA, and the utilities in both the ‘sitting’ and ‘not sitting’ health states,” explained the researchers. “Results from the probabilistic sensitivity analyses found that nusinersen had a zero likelihood of achieving a cost-effective ratio of less than $500,000 per QALY gained.”
Cost effectiveness was calculated after determining that nusinersen led to greater QALYs and LYs (3.24 and 7.64, respectively) than BSC (0.46 and 2.40, respectively), and over a lifetime, the total costs associated with nusinersen were approximately $3.9 million compared with $790,000 for BSC.
“Given the relatively short-term effectiveness and utility data available, a registry to collect long-term data relating to efficacy and utility within infantile-onset SMA patients on treatment is recommended to allow a more accurate estimate of cost-effectiveness,” noted the researchers, who relied on short-term data from the ENDEAR and SHINE clinical trials. They highlight that most of the limitations of their study relate to the lack of available robust data and assumptions required to overcome it.
Their model, which took a health care sector perspective, used 5 health states: permanent ventilation, not sitting, sitting, walking, and death.
The researchers also performed scenario analyses to see if alternative inputs altered the cost-effectiveness results. For example, they used a scenario that took a modified societal perspective and found that the incremental cost per QALY and incremental cost per LY gained for nusinersen compared with BSC were slightly less favorable.
According to the researchers, this was because nonmedical costs, such as modifying the home, accrue for all the health states for a lifetime while patient productivity gains are only used for patients sitting or walking between the ages of 25 and 67 years. In the model, the productivity gains did not offset nonmedical costs since less than 20% of patients receiving nusinersen were in the “sitting” health state and none were in the “walking” health state.
Thokala P, Stevenson M, Kumar V, Ren S, Ellis A, Chapman R. Cost effectiveness of nusinersen for patients with infantile-onset spinal muscular atrophy in US. Cost Eff Resour Alloc. Published online October 6, 2020. doi:10.1186/s12962-020-00234-8.