The incidence of conversion to secondary progressive MS (SPMS) decreased significantly following the introduction of first-generation disease modifying therapies (DMTs), according to study results published in Multiple Sclerosis and Related Disorders. Researchers examined two consecutive population cohorts of patients with relapsing remitting MS before DMT availability (N=2,161) and after (N=3,510) to determine the risk for transition to SPMS. The risk for SPMS conversion, when adjusted for current age, current time since onset, calendar year, and sex, was significantly lower in the post-DMT cohort compared with the pre DMT cohort (HR, 0.58), and the risk for SPMS
conversion per calendar year decreased by 2.6% annually (P<0.001) after 1995, when DMTs first became available. The risk for SPMS conversion went up with age until 50 and was unchanged thereafter or reduced among those with early-onset MS (age, <35), but continued to rise with onset at higher age. Trends were similar between treated and
untreated subgroups.
