# Efficacy
Keywords: TYSABRI, Multiple Sclerosis, Observational Study, ARR, EDSS, Natalizumab, Long-term Safety, Disability Improvement

> This page provides information about the efficacy of TYSABRI, including data from observational studies, long-term safety profiles, and its impact on disability and relapse rates in patients with relapsing-remitting multiple sclerosis (RRMS).

## Details
- [Clinical and Radiological Pivotal Data](#): Overview of key clinical and radiological findings supporting TYSABRI's efficacy.
- [TYSABRI Observational Programme](#): Summary of a long-term observational study evaluating safety and efficacy, including ARR reduction and disability progression.
- [NEDA](#): Information on achieving No Evidence of Disease Activity (NEDA) with TYSABRI treatment.
- [Study Information](#): Details about the TYSABRI Observational Programme, including endpoints and patient enrollment numbers.
- [15-Year Analysis](#): Highlights from a 15-year analysis of TYSABRI’s impact on ARR and disability improvement.
- [UK 15-Year TOP Poster](#): Summary of UK-specific data presented at EAN 2023, showcasing TYSABRI's long-term effectiveness and safety.
- [Adverse Event Reporting](#): Instructions for reporting adverse events in the UK and Ireland, including contact details for Biogen.