Table 1.

Pre-MS and MS subtypes as potential targets for oral therapies

RRMS subtype	Definition	Risk of second episode/ARR over 2 years
Pre-MS
RIS13	Inflammatory lesions on MRI in the absence of clinical symptoms indicative of a related neurological episode RIS could underlie the subsequent development of RRMS or PPMS	31% (52/166)169
CIS12	A single inflammatory neurological event. Subdivided based on number of MRI lesions present initially MRI: <three lesions on MRI there is a <10% risk of MS at 15 years. If ≥three lesions the risk of MS is 50% at 15 years	<3 MRI lesions: 10% ≥3 MRI lesions: 45%170
MS
“McDonald Criteria” MS8	Single neurological episode with MRI evidence of dissemination in time and space	41%171
Clinically definite MS	Two relapses disseminated in time and space. Group 1: CDMS from 1996, Group 2: CDMS from 2008	Group 1: 1.2 relapses/year Group 2: 0.5 relapses/year21
RES RRMS14	Two clinically significant relapses in one year and one or more gadolinium-enhancing lesions on brain MRI or a significant increase in T2 lesion load	1.46 relapses/2 year172

Note: Risk of second episode and ARR are based on trial placebo data.

Abbreviations: ARR, annualized relapse rate; CIS, clinically isolated syndrome; RES, rapidly evolving severe; RIS, radiologically isolated syndrome; RRMS, relapsing-remitting multiple sclerosis.