Lublin FD, Reingold SC, Cohen JA, et al.  Defining the clinical course   of multiple sclerosis: the 2013 revisions.  Neurology 2014;   83:278=286.
  The new classification supplants the 1996 version by Lublin et al. with   four types of MS.  Old system has PPMS, RRMS, @PMS, and progressive   relapsing.
  New classification adds CIS, NOT RIS
  deletes progressive relapsing
  Active MS is those who have clinical relapses or worse MRI's in one year   time frame.
  worsening MS is impairment due to relapses
  progression is progression of disability in a patient with progressive MS   independent of relapses
  Thus patients may have relapsing MS that is active or inactive,  with   or without worsening
  and may have primary or secondary progressive disease that is active or   inactive with or without progression
  Confirmed worsening specifies a time perido and replaces sustained   worsening.  
  Benign and malignant MS are retained but to be used   sparingly