Expanded disability status scale progression assessment heterogeneity in multiple sclerosis according to geographical areas.

Using placebo data from 3 randomized multiple sclerosis (MS) trials with uniform inclusion criteria, we investigated heterogeneity of Expanded Disability Status Scale (EDSS) progression by geographical areas. Our analysis revealed a significantly lower EDSS progression in Eastern European countries (10.8%) compared with Western Europe (13.1%) or the USA/Canada (21.4%, p < 0.001); EDSS improvement behaved the same way. This heterogeneity is not explained by differences of baseline variables. No differences were detected on more easily quantifiable measures, the Timed 25-Foot Walk or the Multiple Sclerosis Functional Composite. At a time when disease progression represents the target for future interventions in MS, establishment of more quantitative and objective outcomes remains a key priority of MS research. Ann Neurol 2018;84:621-625.