OBJECTIVES : Until recently, the approach to preventing NMOSD relapses has been with unapproved, off-label immunosuppressant therapies (ISTs) potentially leaving patients at risk of experiencing poor outcomes. Satralizumab was recently approved in Canada based on a statistically and clinically meaningful reduction in the risk of relapse shown in the SAkuraSky and SAkuraStar (SAkura) trials. Eculizumab also demonstrated positive results; however, the high cost of therapy and requirement for access to an infusion center may limit its viability.

METHODS : To understand the economic implications of the approved therapies from the societal perspective, a de novo, Markov model was developed to estimate the cost-effectiveness of satralizumab versus eculizumab. Health states were defined based on the Expanded Disability Status Scale (EDSS); transition probabilities were based on natural history of NMOSD (preventing patients from improving their EDSS) which is in line with Canadian payers preferred assumption on the NMOSD disease course. A Network Meta-Analysis (NMA) was performed to inform comparative treatment effects. Utilities were calculated from EQ-5D values collected during the SAkura trials. Life years, quality-adjusted life years (QALYs) and costs (reported as 2021 Canadian dollars) were discounted at an annual rate of 1.5%, over a life-time horizon.

RESULTS : Deterministic results demonstrated that satralizumab was the most cost-efficient treatment strategy. Over a life-time horizon, use of satralizumab results in substantially lower costs and slightly lower, but comparable, clinical outcomes relative to eculizumab. The base case ICER is $3.65M per QALY (the south-west quadrant with both negative costs and outcomes). Results were similar probabilistically, nearly all iterations showing satralizumab would be the cost-efficient therapy. Use of satralizumab would result in life-time, discounted savings of over $9.5M per patient.

CONCLUSIONS : Satralizumab may be considered a cost-effective therapy in the treatment of NMOSD in adult and adolescent patients who are AQP4 seropositive.