Abstract
Objective To investigate the association between early relapses shortly after relapsing remitting multiple sclerosis (RRMS) onset and disability progression during secondary progressive MS (SPMS).
Methods In this observational cohort study, 4,988 patients from the MSBase registry who reached SPMS, defined by the Lorscheider criteria, were identified. 1220 patients followed within two years from RRMS onset and over at least one year after SPMS conversion, and with an EDSS score of 4 to 5.5 at SPMS conversion, were included. The outcome was the rate of disability progression during SPMS, calculated with linear regression as mean change in multiple sclerosis severity scores (MSSS) over time. Associations between early disease characteristics (especially annualised relapse rate during the first two years of MS and relapse recovery) with the MSSS change were assessed using multivariable linear regression.
Results Of 1220 patients, 67% were female and the median age of MS diagnosis was 40 years. We found no evidence for association of early relapse rate with disability progression (β=-0.014, 95% CI -0.067 to 0.037, p=0.60). Male sex, a longer RRMS period and a higher EDSS at progression were associated with faster SPMS disability progression. A higher initial MSSS was associated with slower disability progression. Importantly, a higher proportion of early relapses with incomplete recovery was associated with faster disability progression during SPMS (β=0.12, 95% CI 0.017 to 0.22, p=0.025)
Conclusion The rate of relapses during early RRMS is not associated with SPMS disability progression, while incomplete recovery of early relapses is associated with faster disability progression.
