Abstract :
Background
Previous trials of interferon β in multiple sclerosis (MS) have shown efficacy, but the degree of clinical benefit remains uncertain, and the optimum dose is not known. We undertook a double-blind, placebo-controlled study in relapsing/remitting MS to investigate the effects of subcutaneous interferon β-1a.
Methods
560 patients with Kurtzke expanded disability status scale (EDSS) scores of 0–5·0, from 22 centres in nine countries, were randomly assigned subcutaneous recombinant interferon β-1a 22 μg (n=189), or 44 μg (n=184), or placebo (n=187) three times a week for 2 years. Neurological examinations were done every 3 months. All patients had MRI twice yearly and 205 had monthly scans in the first 9 months of treatment. Analysis was by intention to treat.
Findings
Clinical data on 533 (95%) patients were available at 2 years. The relapse rate was significantly lower at 1 and 2 years with both doses of interferon β-1a than with placebo (mean number per patient 1·82 for 22 μg group, 1·73 for 44 μg group vs 2·56 for placebo group: risk reductions 27% [95% Cl 14–39] and 33 [21–44]). Time to first relapse was prolonged by 3 and 5 months in the 22 μg and 44 μg groups respectively, and the proportion of relapse-free patients was significantly increased (p < 0·05). Interferon β-1a delayed progression in disability, and decreased accumulated disability during the study. The accumulation of burden of disease and number of active lesions on MRI was lower in both treatment groups than in the placebo group.
Interpretation
Subcutaneous interferon β-1a is an effective treatment for relapsing/remitting MS in terms of relapse rate, defined disability, and all MRI outcome measures in a dose-related manner, and it is well tolerated. Longer-term benefits may become clearer with further follow-up and investigation.
