Secondary progressive multiple sclerosis may start later and go slower than PPMS

Secondary progressive multiple sclerosis (SPMS) patients appear to have slower worsening disability than people with primary progressive MS (PPMS), a new study has found.

But, those with SPMS do tend to be generally older and their disability tends to be more advanced when their condition enters the progressive stage. Because of this, those with both forms are likely to reach disability milestones like needing to use a wheelchair at similar ages.

The most common type of MS is relapsing-remitting, which sees people often have symptom-free periods, followed by relapses. Some of these people progress to SPMS, where their MS symptoms worsen independent of relapses.

Around one in ten people with MS will have PPMS, in which the worsening happens from disease onset, whether they have relapses or not.

The findings are consistent with the differences in age at onset and progression rates for both groups of patients. Collectively, the data suggest that PPMS patients tend to accrue disability more quickly than those with SPMS — but because SPMS patients usually have noteworthy disability already when they enter the progressive phase, people with either form of MS tend to be similar ages when they hit disability milestones.

This may have implications for designing clinical trials, the researchers noted. “One should exercise caution about combining PPMS and SPMS in clinical trials and consider the difference in disability trajectories when comparing disability outcomes,” they wrote.