This is a question that lurks in the minds of many people diagnosed with relapsing-remitting MS (RRMS). For many of us, every twinge brings the worry that this is the beginning of progression to secondary-progressive MS (SPMS). New research indicates that as we age with RRMS, we may not have to worry about this quite as much.
An estimated 85% of people living with multiple sclerosis (MS) are initially diagnosed with RRMS. Some of these people will eventually develop secondary-progressive MS, which is characterized by a more steady progression of symptoms and disability and fewer or no relapses.
It used to be assumed that 80 to 90% of people with RRMS would eventually develop SPMS within 25 years (50% within 10 years) of diagnosis, although people living with MS were not followed for a sufficient length of time to really know what was happening.
SPMS is diagnosed when a person who was initially diagnosed with RRMS has worsening symptoms and/or disability without relapses for 6 months or more.
Collaborating researchers from Turkey, Lebanon and the US wanted to determine the percentage of people with relapsing-remitting MS that will never develop secondary progressive (SPMS). They combined two databases of people living with MS in order to derive the information. Of these people, approximately 30% had taken disease-modifying therapy.
The researchers found that our age impacts our chances of developing progressive MS. SPMS is typically diagnosed at an average age of 45 years, plus or minus 10 years, regardless of when people are diagnosed with RRMS. Interestingly, primary-progressive MS also tends to be diagnosed at the same age.
What does the "age effect" of the risk of progressive MS mean in terms of risk of developing SPMS?
Although it seems logical that the longer you live with RRMS, the closer you may be getting to converting to SPMS. Once you are older than 45, this does not seem to be the case. In fact, the opposite is true.
Once a person with RRMS is older than 45, their risk of converting to SPMS drops to 35%.
A person older than 50 only has a 20% risk of developing SPMS.
After age 60, the risk of SPMS conversion drops to 7%.
After 75 years of age, if a person with RRMS has not developed SPMS, it is extremely unlikely (less than 1% chance) that they will develop SPMS.
Based on the data, researchers estimate that between 43-38% of people with RRMS will never develop SPMS, even if they are followed until they are 75 years old.
I don’t have to tell you that this is good news for those of us who are middle-aged and living with relapsing-remitting MS. In my opinion, the fact that our risk of developing progressive disease actually continues to decrease as we age is one of the few positive side effects of getting older.