Fewer clinical trials
focus specifically on progressive-relapsing MS (PRMS) than any other course of MS for two important reasons:
PRMS may be more difficult to diagnosis or to distinguish from other disease courses, at least initially.
PRMS is the least common disease course, which means that it is difficult to recruit adequate numbers of people to participate.
Depending on the specific inclusion criteria used in a given trial, people with PRMS may or may not be invited to participate. When they are included, it tends to be in trials for symptomatic management medications.
Read more about research in progressive MS.