Background: SMA is a debilitating genetic motor neuron disease, usually caused by biallelic deletion of the SMN1 gene. Disease severity (i.e., SMA clinical type) generally correlates with variable copy number of the SMN2 gene — a partially functional paralog of SMN1. Three disease-modifying treatments (DMTs) are approved for SMA treatment in the United States. Two of these are SMN2 gene splicing modifiers that require ongoing (presumably lifelong) administration: nusinersen, given as intrathecal injections, and risdiplam, a daily oral medication. Onasemnogene abeparvovec is a one-time intravenous (IV) gene replacement therapy that delivers a functional human SMN gene to target motor neurons. Data on caregiver preferences for different treatment characteristics that may inform choice of DMT are limited.
Objective: We sought to examine preferences for caregivers of patients in the US affected by SMA type 1 (non-sitters) or 2 (sitters) and preferences for different SMA DMT attributes. A preference study conducted with caregivers of patients with SMA types 1 or 2 was performed using swing weighting methodology. The results of the swing weighting exercise were used to estimate the relative value of hypothetical SMA DMT profiles exploring different modes of treatment administration.
Results: Twenty caregivers of patients with SMA type 1 or type 2 participated. Attributes with the greatest impact on treatment preference were decreases in permanent ventilation needs and reduction in risk of severe adverse events, followed by treatment covered by insurance, increased ability to sit without support, and less impact of treatment administration. Caregivers often preferred a DMT profile with reduced clinical burden, less risky treatment administration methods, and quick access to treatment covered by insurance.
Conclusions: Treatment administration can have a substantial impact on caregivers. The quantitative and qualitative parts of this study found that one-time IV infusion was preferred to all other options, and the benefits of less risk, less frequent, and less invasive procedures were reasons for preference over spinal injection options. Valuation of hypothetical treatments identified the burden of treatment administration as the driving force of the ranking of treatments. Patient and caregiver preferences should be considered by health care decision makers when determining the most suitable treatment option for individualized SMA disease management.