ON DECEMBER 9,1993, the New England Journal of Medicine reported the latest and most important finding from the Optic Neuritis Treatment Trial (ONTT).1 Intravenous methylprednisolone (1 g/d for 3 days), followed by oral prednisone (1 mg/kg per day for 11 days), prescribed for patients with acute, isolated optic neuritis, reduced the 2-year incidence of definite multiple sclerosis (MS) by more than 50%.
Definite MS was diagnosed in the ONTT as soon as the patient experienced a new neurologic development, excluding recurrent optic neuritis, at least 4 weeks after entry, and was accompanied by appropriate physical abnormalities noted by the study neurologist. Among the 389 patients in the ONTT who did not have MS at study entry, 10 (7.5%) of 134 intravenously treated patients developed at least one such neurologic event within 2 years compared with 21 (16.7%) of 126 placebo-treated patients. This was an impressive difference. The relative risk