It is expressed as a percentage indicating the yearly risk of such transition at the present time. It can be repeated at any time during the course. The calculator will use the time difference between the last attack and the present day. This capacity distinguishes the MS Prediction Score from prognosis of the distant risk based on data from onset or from the early course. It is derived from the Gothenburg multiple sclerosis incidence cohort*.
The consensus definition of secondary progression is as follows: Initial relapsing-remitting disease course followed by progression with or without occasional relapses, minor remissions and plateaus**. We refer to insidious progression as a disease course that usually leads to considerable disability, and often heralded by a progressive pyramidal syndrome.
* Runmarker and Andersen, Brain 1993; Skoog et al, Brain 2012; Tedeholm et al, Multiple Sclerosis J 2013
** Lublin and Reingold, Neurology 1996.