For the first time since 1996, the definitions used to describe the different types of multiple sclerosis (MS) have been fine-tuned. Science has made huge advancements in diagnostic imaging and identifying biomarkers for MS since the original subtypes, or “phenotypes,” were first defined.
A committee made up of members of the National MS Society (the Society), the European Committee for Treatment and Research in MS, better known as ECTRIMS, and the MS Phenotype Group collaborated in the effort to redefine MS subtypes and take into account the great strides made in the field over the past two decades.
Out with the Old, in with the New
The 1996 definitions categorized a person’s MS course as either relapsing-remitting, secondary-progressive, primary-progressive, or progressive-relapsing. Under the new definitions, however, the "progressive-relapsing" phenotype has been dropped. Instead, it is described as an “active” form of primary-progressive MS.
Progressive-relapsing may be out, but clinically isolated syndrome, or CIS, is now in. This means that patients with a single MS event can be diagnosed more quickly, based on the better brain imaging techniques now available. With a definite MS diagnosis, patients may be able to start taking a disease modifying therapy (DMT) sooner—a step that the Society recommends to help lower the odds of becoming disabled.
The team also opted to add “modifiers," like adjectives added to a sentence, to more accurately describe a patient's phenotype.
Until now, someone with relapsing-remitting MS might have attacks three or four times per year, yet share the same phenotype as someone who may not recall the last time they had a flare-up. The new revisions address this disparity.
“Active” or “not active” will denote relapses, while “progressing” and “not progressing” will indicate the accumulation of disability. So someone with relapsing-remitting MS who has been having flare-ups but recovers fully will be described as having “relapsing-remitting MS that is active, not progressing”.
Using these modifiers will paint a clearer picture of the patient’s current disease state for everyone, from neurologists to physical therapists, and convey it in an understandable way.
Modifiers will also help researchers identify patients whose disease is “active” or “progressing.” Study subjects can then be chosen more selectively for clinical trials of DMTs, which are increasingly becoming more targeted and more sophisticated.
A Patient’s Perspective
How do patients feel about these new disease definitions?
“Being moved from one [phenotype] to another is still so subjective, even with these new definitions,” Anne Pappas, who lives with relapsing-remitting MS in Atlanta, GA, told Healthline. “Almost any neurologist, I believe, will continue to maintain a diagnosis level which will allow their patient access to any necessary [DMTs].”
Jessica Petroff agrees with the modifications, “to a point,” she told Healthline. Petroff, a certified medical assistant at a family practice in Indianapolis, IN, is living with a diagnosis of relapsing-remitting MS.
For those hovering between relapsing-remitting and transitioning into secondary-progressive, Petroff points out, it could be better to have relapsing-remitting MS tagged with a modifier of “progressing” rather than to be given a diagnosis of secondary-progressive MS.
“I don't like the idea of, once a person falls into a certain category of [secondary-progressive] or [primary-progressive] ‘not active,’ that it is possible they will not be offered any more treatment,” Petroff said.
The subtleties in disease definitions could have huge implications for insurance coverage. Drugs deemed effective for relapsing-remitting MS are often not covered by insurance if you are diagnosed with any other MS phenotype.
“At the end of the day, patients are just scared to death of anything occurring that will impede their ability to get [DMTs],” said Pappas. “When all is said and done, I don't care what you call me, just don't call me anything that will take away my ability to try any medical therapy or clinical trial out there.”