Protocol Adherence in Spinal Muscular Atrophy Treated with Nusinersen and Risdiplam: A Retrospective Registry-Based Pharmacoclinical Audit

Objective: Disease-modifying therapies such as nusinersen and risdiplam have significantly changed the management of spinal muscular atrophy (SMA). In Spain, both are reimbursed under a national pharmacoclinical protocol with registry-based monitoring. The objective was to evaluate protocol adherence and treatment patterns in routine clinical practice. Methods: A retrospective registry-based pharmacoclinical audit was conducted in a tertiary hospital within the Spanish National Health System. The primary purpose of the audit was to assess adherence to the national SMA pharmacoclinical protocol and the completeness of routinely collected registry data. Patients with genetically confirmed SMA receiving nusinersen or risdiplam were identified from pharmacoclinical registries linked to national monitoring systems (VALTERMED). Demographic data, SMA phenotype, SMN2 copy number, treatment initiation, therapy sequence, and persistence were analyzed descriptively. Descriptive analysis of continuous and categorical variables; no inferential testing was performed. Results: Sixteen patients were included (nusinersen n=6; risdiplam n=10). All nusinersen-treated patients fulfilled protocol criteria with complete documentation. Seven risdiplam-treated patients met eligibility criteria with full documentation, while three had incomplete registry variables without evidence of off-protocol use. Phenotype severity and SMN2 distribution were comparable. Treatment persistence was 100% in both groups. Risdiplam was more frequently used in older patients and after prior nusinersen. Conclusion: Both therapies were implemented according to national protocol criteria. Differences reflected treatment pathways and documentation completeness. Registry-based monitoring provides valuable real-world evidence on SMA therapy implementation.