Onset of secondary progressive multiple sclerosis is not influenced by current relapsing multiple sclerosis therapies

BackgroundDisease-modifying therapies are thought to reduce the conversion rate to secondary progressive multiple sclerosis.ObjectiveTo explore the rate, chronology, and contributing factors of conversion to the progressive phase in treated relapsing–remitting multiple sclerosis patients.MethodsOur study included 204 patients treated for relapsing–remitting multiple sclerosis between 1995 and 2002, prospectively followed to date. Kaplan–Meier analysis was applied to estimate the time until secondary progressive multiple sclerosis conversion, and multivariate survival analysis with a Cox regression model was used to analyse prognostic factors.ResultsRelapsing–remitting multiple sclerosis patients were continuously treated for 13 years (SD 4.5); 36.3% converted to secondary progressive multiple sclerosis at a mean age of 42.6 years (SD 10.6), a mean time of 8.2 years (SD 5.2) and an estimated mean time of 17.2 years (range 17.1–18.1). A multifocal relapse, age older than 34 years at disease onset and treatm...