TOP is an epidemiological observational study of participants receiving natalizumab, with each participant to be followed for up to 15 years. This study is designed to address the long-term safety profile and the long-term impact on disease activity and progression of Tysabri with marketed use, and the impact of treatment on disability in particular by comparing the results with prospectively determined controls from established databases.
The primary objective of this study is to assess the long-term safety and impact on disease activity and progression of Tysabri in participants with relapsing remitting multiple sclerosis (RRMS) in a clinical practice setting.