Multiple sclerosis from onset to secondary progression: a 30-year Italian register study.

Background: Three decades have passed since the initial approval of disease-modifying therapies (DMTs). Ongoing discussion is focused on fundamental aspects of the disease, highlighting a growing division between successes in managing relapsing multiple sclerosis (MS) and the persistent challenges posed by disease progression.

Methods: A cohort study on prospectively acquired data from the Italian MS register. The primary outcome was to describe the MS disease course from onset to secondary progression (SP) defined according to a data-driven algorithm over 30 years follow-up and according to five different eras of disease onset.

Results: A total cohort of 9958 patients was analysed; 1364 converted to SP after a mean of 8.5 (SD 5.5) years. A higher rate of patients converting to SP had never been exposed to DMTs (135, 9.9% vs 424, 5.2%) than non-converting ones. The treatment coverage was also lower in patients converting to SP than non-converting ones 58.4 (SD 31.5) vs 73.6 (SD 27.6).The SP incidence rate was 1.26 (95% CI 1.19 to 1.32) overall. The rates showed a downward trend among the different eras: from 1st era 1.98 (95% CI 1.73 to 2.27) to 5th era 1.15 (95% CI 0.97 to 1.35).In the multivariable Cox model, 10% increase of treatment coverage was associated to 19% lower risk to convert to SP (10%, HR 0.89, 95% CI 0.87 to 0.90).

Conclusions: This 30-year analysis suggests that SP conversion rates have decreased over time, partially explained by improvements in therapeutic coverage. Future research should adopt a multifaceted approach to develop more comprehensive models of disease progression.