Long-term clinical relevance of criteria for designating multiple sclerosis as benign after 10 years of disease

Objectives: To determine the long-term outcome of a cohort of 436 patients with multiple sclerosis (MS) seen in 1985 and long-term predictors of benign MS. Methods: The initial 1985 group of 436 patients with possible MS, including 53 benign patients, were followed for 21 years. Disability was recorded using the Expanded Disability Status Scale (EDSS). Survival from disease onset was calculated. The indicators of benign MS in the initial 1985 cohort and in the survivors in 2006 were determined. Results: Of the original 436 patients, the 21-year follow-up outcome in 397 (91%) was established. The diagnosis of MS was incorrect in 41/397 (10%) of the whole cohort and in 2/53 (4%) of the benign group. Median survival of 356 patients with MS was 43.6 years from disease onset. Of 47/51 (92%) patients with benign MS followed in 2006, 7 (15%) remained benign, 18 had died and 22 were disabled. Median survival advantage for the 47 benign patients in 1985 compared to the 88 non-benign patients, when corrected for age, was 6 years (p<0.08). In 2006, 40/356 (11%) patients had a benign outcome at a mean follow-up of 26.1 years. A benign course was significantly associated with female sex, younger age of onset and absence of motor symptoms at presentation. Conclusions: Although designating patients as having a benign course after 10 years has a poor predictive value, three factors at presentation indicate a better prognosis.