Table 2.

Proportion of patients with relapses or confirmed disability progression, Year 2 (PRISMS-2) and 4 (PRISMS-4)

	Placebo/delayed treatment (n = 187)	IFN β-1a 22 μg SC tiw (n = 189)	IFN β-1a 44 μg SC tiw (n = 184)
Relapse by Year 2 (%)	84.5	73.0	67.9
Relapse by Year 4 (%)	90.4	82.0	78.8
Confirmed EDSS progression by Year 2 (%)	39.0	31.2	27.7
Confirmed EDSS progression by Year 4 (%)	48.1	45.0	39.7

EDSS progression was defined as an increase of ≥0.5 points if baseline EDSS was ≥6 or increase of ≥1 point if baseline EDSS was < 6, confirmed 3 months later

EDSS Expanded Disability Status Scale, IFN β-1a interferon beta-1a, SC subcutaneously, tiw three times weekly