Interferon beta-1 a for optic neuritis patients at high risk for multiple sclerosis

PURPOSE: To evaluate the effect of treatment with interferon beta -1a (Avon ex) initiated at the time of a first episode of optic neuritis in patients at high risk for multiple sclerosis (MS). DESIGN: Randomized clinical trial METHODS: Prospective. SETTING: Fifty clinical centers throughout the US and Canada. STUDY POPULATION: After the onset of a first episode of optic neuritis trea ted with intravenous and oral corticosteroids, 192 patients with brain magn etic resonance imaging (MRI) evidence of subclinical demyelination were ran domly assigned to receive weekly intramuscular injections of 30 mug interfe ron beta -1a or placebo. MAIN OUTCOME MEASURE: The study outcomes were the development of clinically definite MS within 3 years of follow,up and brain MRI changes at 6, 12, an d 18 months. RESULTS: The rates of clinically definite MS and of a combined MS/MRI outco me were lower in the interferon beta -1a group than in the placebo group (a djusted rate ratios 0.58, 95% confidence interval 0.34 to 1.00; and 0.50, 9 5% confidence interval 0.34 to 0.73, respectively). Compared with the place bo group, on the 18,month brain MRI the interferon beta -1a group had a sma ller change from baseline in T2 lesion volume (P = .02), fewer new or enlar ging T2 lesions (P < .001), and a lower frequency of Gd-enhancing lesions ( P < .001). CONCLUSION: The clinical and brain MRI results of this trial support initia ting interferon beta -1a treatment at the time of a first episode of optic neuritis occurring in patients at high risk for MS based on the presence of subclinical brain MRI lesions. (C) 2001 by Elsevier Science Inc. All right s reserved.