Longitudinal Efficacy of Nusinersen Treatment on Health-Related Quality of Life and Independence in Children With Later-Onset Spinal Muscular Atrophy

Introduction/Aims: The rising use of disease-modifying therapy is progressively impacting the health-related quality of life (HRQoL) of patients with spinal muscular atrophy (SMA) in their daily lives. This study aimed to evaluate the changes in HRQoL and independence in children with later-onset SMA receiving longitudinal treatment with nusinersen. Methods: Forty-nine pediatric patients with later-onset SMA (symptom onset after 6 months of age) and their caregivers were enrolled. The HRQoL of patients evaluated by the proxy-reported Pediatric Quality of Life Inventory 3.0 Neuromuscular Module (PedsQL NMM) and the independence level determined by the SMA Independence Scale-Upper Limb Module (SMAIS-ULM) were assessed. Caregiver HRQoL was assessed using the Pediatric Quality of Life Inventory Family Impact Module (PedsQL FIM). Motor function was recorded using the Hammersmith Functional Motor Scale Expanded (HFMSE) and the Revised Upper Limb Module (RULM), with subsequent analysis of the correlation between motor function, HRQoL, and independence scores. Results: A significant difference was observed across all domains of the proxy-reported PedsQL NMM and in the independence assessment over the 18-month follow-up period (p < 0.001). A positive correlation was identified between RULM and total PedsQL NMM scores (Pearson-r = 0.539, p < 0.001), as well as SMAIS-ULM scores (Spearman-rho = 0.507, p < 0.001). Scores in all modules of the PedsQL FIM improved over time (p < 0.001). Discussion: This study demonstrates the longitudinal effects of nusinersen treatment on multifaceted aspects of SMA patients, as captured by patient-reported outcome measures (PROMs). The inclusion of PROMs should be considered as part of the SMA multidisciplinary assessment.