Clinical and radiological activity of secondary progressive multiple sclerosis in a population-based cohort

Background and purpose: Patients with secondary progressive multiple sclerosis (SP MS) and clinical and/or radiological activity could be the more likely to benefit from disease-modifying treatments. To evaluate the proportions each year after progression onset, patients with SP MS onset between 2002 and 2012 from a population-based multiple sclerosis registry in northeastern France were studied.

Methods: Progression onset was first identified by the neurologist's diagnosis (N cohort), and then by using an automated data-driven definition (D cohort). In a given year after onset of progression, clinical activity was defined as at least one relapse, and radiological activity as at least one new T2 and/or gadolinium-enhancing lesion. A multivariate mixed logistic regression was used to assess factors associated with activity during the year.

Results: In the N cohort, amongst 833 patients with SP MS with a median follow-up of 8 years, 10.0%-14.8% had at least one relapse in a year during the first 5 years of progression. Including both clinical and radiological activity increased these proportions to 11.9%-23.7%, with the proportion having a magnetic resonance imaging scan in the year ranging from 29.8% to 40.5%. The first year of progression, a young age and a high relapse rate during the 5 years before progression were associated with activity in a given year. The D cohort results confirmed these findings.

Conclusions: A substantial proportion of patients with SP MS present disease activity. Further studies should evaluate the impact of disease-modifying treatments on the disease course of these patients.