Onasemnogene Abeparvovec Gene Therapy and Risdiplam for the Treatment of Spinal Muscular Atrophy in Thailand: A Cost-Utility Analysis

Abstract

Objectives: Caring for individuals with spinal muscular atrophy (SMA), a rare genetic disorder, poses tremendous challenges for the economy and healthcare system. This study evaluated the cost-utility of onasemnogene abeparvovec-xioi gene therapy and risdiplam for SMA in Thailand. Methods: A Markov model was used to analyze the lifetime costs and outcomes of these treatments compared with standard of care for symptomatic SMA types 1 and 2–3. SMA type 1 patients were treated with one of either onasemnogene or risdiplam, while SMA types 2–3 patients received risdiplam. Data on disease progression and medical costs were sourced from hospital databases, while treatment efficacy was based on clinical trials. Interviews with patients and caregivers provided data on non-medical costs and utilities. Base case cost-effectiveness and sensitivity analyses were conducted, with the incremental cost-effectiveness ratio (ICER) calculated in US dollars (USD) per quality-adjusted life year (QALY) gained, against a willingness-to-pay threshold of 4444 USD/QALY gained. Results: For SMA type 1, the ICERs for onasemnogene and risdiplam were 163,102 and 158,357 USD/QALY gained, respectively. For SMA types 2–3, the ICER for risdiplam was 496,704 USD/QALY gained. Conclusions: While onasemnogene and risdiplam exceeded the value-for-money threshold of the Thai healthcare system, they yielded the highest QALY gains among all approved medications. Policy-makers should incorporate various pieces of evidence alongside the cost-effectiveness results for rare diseases with costly drugs. Additionally, cost-effectiveness findings are useful for price negotiations and alternative financial funding, which allows policy-makers to seek solutions to ensure patient access, aligning with universal health coverage principles in Thailand.