Cognitive dysfunction is common in multiple sclerosis (MS), yet few studies have examined effects of treatment on neuropsychological (NP) performance. To evaluate the effects of interferon β‐1a (IFNβ‐1a, 30 μg administered intramuscularly once weekly [Avonex]) on cognitive function, a Comprehensive NP Battery was administered at baseline and week 104 to relapsing MS patients in the phase III study, 166 of whom completed both assessments. A Brief NP Battery was also administered at 6‐month intervals. The primary NP outcome measure was 2‐year change on the Comprehensive NP Battery, grouped into domains of information processing and learning/memory (set A), visuospatial abilities and problem solving (set B), and verbal abilities and attention span (set C). NP effects were most pronounced in cognitive domains vulnerable to MS: IFNβ‐1a had a significant beneficial effect on the set A composite, with a favorable trend evident on set B. Secondary outcome analyses revealed significant between‐group differences in slopes for Brief NP Battery performance and time to sustained deterioration in a Paced Auditory Serial Addition Test processing rate, favoring the IFNβ‐1a group. These results support and extend previous observations of significant beneficial effects of IFNβ‐1a for relapsing MS. Ann Neurol 2000;48:885–892

In patients with relapsing MS and only mild to moderate disability, significant cerebral atrophy is already developing that can be measured over periods of only 1 to 2 years. The course of cerebral atrophy in MS appears to be influenced by prior inflammatory disease activity as indicated by the presence of enhancing lesions. Brain atrophy measures are important markers of MS disease progression because they likely reflect destructive and irreversible pathologic processes.

The Multiple Sclerosis Collaborative Research Group trial was a double-blind, randomized, multicenter, phase III, placebo-controlled study of interferon beta-1a (IFNbeta-1a; AVONEX) in relapsing forms of multiple sclerosis. Initial magnetic resonance imaging results have been published; this report provides additional results. Treatment with IFNbeta-1a, 30 microg once weekly by intramuscular injection, resulted in a significant decrease in the number of new, enlarging, and new plus enlarging T2 lesions over 2 years. The median increase in T2 lesion volume in placebo and IFNbeta-1a patients was 455 and 152 mm3, respectively, at 1 year and 1,410 and 628 mm3 at 2 years, although the treatment group differences did not reach statistical significance. For active patients, defined as those with gadolinium enhancement at baseline, the median change in T2 lesion volume in placebo and IFNbeta-1a patients was 1,578 and -12 mm3 and 2,980 and 1,285 mm3 at 1 and 2 years, respectively. Except for a minimal correlation of 0.30 between relapse rate and the number of gadolinium-enhanced lesions, correlations between MR and clinical measures at baseline and throughout the study were in general poor. Once weekly intramuscular IFNbeta-1a appears to impede the development of multiple sclerosis lesions at an early stage and has a favorable impact on the long-term sequelae of these inflammatory events as indicated by the slowed accumulation of T2 lesions.

We determined inter- and intrarater Kurtzke Expanded Disability Status Scale (EDSS) scoring agreement for four trained examining physicians who evaluated 10 clinically stable multiple sclerosis patients. These patients had previously been determined to have EDSS scores of 1.0 to 3.5 and were scheduled to participate in a funded clinical trial of intramuscular recombinant interferon-beta. Intrarater reliability was greater than interrater reliability for scoring the EDSS and all of its component functional systems scores (FSS). Specifically, individual examiners were able to reproduce three serial examination scores on the same patient on the same day (intrarater agreement) within 1.0 EDSS or 2.0 individual FSS points. Reproducible scoring across examiners (interrater agreement), however, could only be accomplished within 1.5 EDSS or 3.0 individual FSS points. Additionally, the interrater scoring variability in our patients is greater than that previously reported for patients with higher EDSS scores. We conclude that clinical trials that employ the EDSS as an outcome measure of treatment efficacy should include inter- and intrarater agreement data for all examining physicians. Most importantly, studies using a single examining physician to evaluate individual patients throughout the course of a clinical trial will require less change in the EDSS to reliably measure disease activity than will studies using more than one examining physician to evaluate individual patients throughout the trial.