EDSS is an ordinal scale in half-point increments that quantifies disability in participants with MS. It assesses 7 functional systems (visual, brainstem, pyramidal, cerebellar, sensory, bowel/bladder and cerebral) as well as ambulation. EDSS total score: 0 (normal neurological examination) to 10 (death due to MS). As measured by EDSS score, SAD was defined as increase of at least 1.5 points for participants with Baseline score of 0 and increase of at least 1.0 point for participants with Baseline score of 1.0 or more; and the increase persisted for at least next the 2 scheduled assessments, that is, 6 consecutive months. The onset date of SAD was date of first EDSS assessment that began 6 month consecutive period of SAD. Participants who did not reach SAD endpoint were censored at their last visit. Probability of participants with SAD, estimated by Kaplan-Meier (KM) method, was reported.

Relapse was defined as new neurological symptoms or worsening of previous neurological symptoms with an objective change on neurological examination, attributable to multiple sclerosis that lasted for at least 48 hours, that were present at normal body temperature, and that were preceded by at least 30 days of clinical stability. Annualized relapse rate was estimated using a Poisson regression model with observed number of relapses as a dependent variable, the log total amount of follow-up from date of randomization for each participant as an offset variable and treatment group indicator as a covariate.