Clinical implications of benign multiple sclerosis: a 20-year population-based follow-up study.

In 2001, we followed up all patients from the 1991 Olmsted County Multiple Sclerosis (MS) prevalence cohort. We found that the longer the duration of MS and the lower the disability, the more likely a patient is to remain stable and not progress. This is particularly powerful for patients with benign MS with Expanded Disability Status Scale score of 2 or lower for 10 years or longer who have a greater than 90% chance of remaining stable. This is important because these patients represent 17% of the entire prevalence cohort. These data should assist in the shared therapeutic decision-making process of whether to start immunomodulatory medications.