Onset of secondary progressive multiple sclerosis is not influenced by current relapsing multiple sclerosis therapies.

The favourable influence of disease-modifying therapies on long-term disability in relapsing-remitting multiple sclerosis is well established. However, the time to progression onset and the subsequent clinical course in treated patients seem similar to those previously reported in natural history studies. More studies are needed to clarify the effect of disease-modifying therapies once the progressive phase has been reached.