The division of MS in "types" was made up just to approve interferons

[frodo]

Multiple sclerosis – a review

https://onlinelibrary.wiley.com/doi/ful ... /ene.13819

There has been a reduction in the proportion of people with PPMS. This is probably related to the fact that there are no licensed treatments for PPMS; patients may be labelled as having relapsing MS in order to receive treatment, raising ethical questions about the division of MS into distinct subtypes. This artificial division of MS into different diseases was driven by the pharmaceutical industry to get interferon beta licensed under the Orphan Drug Act in the USA.

Here there is a longer explanation:

https://multiple-sclerosis-research.org ... -kool-aid/

The construct that MS has distinct phases, an early inflammatory and a delayed degenerative phase, is artificial and comes from the Pharma industry’s need to get interferon-beta licensed under the orphan drug act, i.e. MS had to have a prevalence of fewer than 200,000 affected people for the orphan drug act to apply. The only way to get the numbers down to less than 200,000 was to salami-slice up MS into three diseases, i.e. RRMS, SPMS and PPMS.

More reports against the classification in "types" here:

viewtopic.php?f=59&t=30871
viewtopic.php?f=59&t=31281

[frodo]

New "type" under research. They are trying to achieve a standard definition for agressive MS. Maybe this will be more interesting than the previous "types". The paper has two parts:

https://journals.sagepub.com/doi/full/1 ... 8520925369
https://journals.sagepub.com/doi/full/1 ... 8520924595

Abstract

While the major phenotypes of multiple sclerosis (MS) and relapsing–remitting, primary and secondary progressive MS have been well characterized, a subgroup of patients with an active, aggressive disease course and rapid disability accumulation remains difficult to define and there is no consensus about their management and treatment.

The current lack of an accepted definition and treatment guidelines for aggressive MS triggered a 2018 focused workshop of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) on aggressive MS. The aim of the workshop was to discuss approaches on how to describe and define the disease phenotype and its treatments.

Unfortunately, it was not possible to come to consensus on a definition because of unavailable data correlating severe disease with imaging and molecular biomarkers. However, the workshop highlighted the need for future research needed to define this disease subtype while also focusing on its treatment and management.

Here, we review previous attempts to define aggressive MS and present characteristics that might, with additional research, eventually help characterize it. A companion paper summarizes data regarding treatment and management