Real-World Impact of National Policy on High-Efficacy Therapy Use in Multiple Sclerosis: A Brazilian Big Data Analysis

Background In 2021, Brazil updated its Clinical Protocol and Therapeutic Guidelines (PCDT) for multiple sclerosis (MS), expanding first-line eligibility for natalizumab (NTZ) in patients with highly active disease and incorporating alemtuzumab (ALE). Evidence on temporal changes in disease-modifying therapy (DMT) dispensation within the Brazilian public health system (SUS) after this update is lacking. Methods Using big data, we analyzed 1,711,342 DMT dispensation authorizations for MS from the national outpatient registry (SIA/SUS) between 2019 and 2023. DMTs were categorized as: high-efficacy (NTZ, ALE), intermediate/moderate-efficacy (FNG), and platform therapies (IFN, GA, DMF, TERI). Quasi-Poisson space-time regression models compared pre-PCDT (2019–2021) and post-PCDT (2022–2023) periods at national and regional levels, while state-level variation was assessed relative to the national mean. Treatment switches were evaluated across periods and regions. Results From 2019 to 2023, the number of MS patients treated through the SUS increased by 25.9%. Nationwide, dispensation of NTZ (+44.5%, p<0.001), DMF (+53.1%, p<0.001), TERI (+32.5%, p<0.001), and FNG (+15.8%, p<0.001) increased, while IFN (–40.3%, p<0.001) and GA (–27.6%, p<0.001) decreased. NTZ increased across all regions, with the largest growth in the North (+82.0%, p=0.042), whereas IFN reduced only in the North (–41.9%, p =0.049). State-level analyses showed heterogeneous NTZ uptake, with higher rates in parts of the Northeast (Ceará, Paraíba, Sergipe), Center-West (Federal District, Goiás), North (Pará), and Southeast (São Paulo), and lower rates across all Southern states. Most treatment switches occurred within the same efficacy class, with no differences between pre- and post-PCDT periods or across regions. ALE dispensation was limited to the late post-PCDT period. Conclusions In this nationwide observational analysis, DMT dispensation patterns in Brazil were characterized by higher NTZ and increased dispensation of FNG, DMF, and TERI in the post-PCDT period. However, persistent regional disparities and conservative switching patterns may suggest barriers to equitable access to HE DMTs. These findings highlight the role of national guidelines in shaping real-world therapeutic practices and the value of administrative data for monitoring treatment patterns and healthcare organization in MS.