That's a really good question, , and I hope our members will chime in here and share.
I know you were probably asking for more of a "roll call" situation, but I did some digging about the transition from RRMS to SPMS. Please take my findings with a grain of salt, as I wasn't researching too deeply. It looks about 10% of individuals transition from RRMS to SPMS within 10 years. That number jumps to 50% at 20 years and 93% at 30 years. Keep in mind that most of this data does seem to originate from one study done in 1989. And, it does not take into consideration treatment options and early interventions. Obviously, things have changed a great deal since then.
But, all this to say is that I know you are in good company. Quite a few of our health leaders are living with SPMS and have written a lot about MS in general and the transition to SPMS. One health leader wrote about it and I wanted to share a link to her piece -- https://multiplesclerosis.net/living-with-ms/rrms-spms-transition; I would be curious to see current data on how many people worldwide transition from RRMS to SPMS. Thanks for posing this question, as it has really peaked my interest and I am curious to see what kind of response you get!
Best, Erin, Team Member.