Predicting multiple sclerosis at optic neuritis onset

Using multivariate analyses, individual risk of clinically definite multiple sclerosis (CDMS) after monosymptomatic optic neuritis (MON) was quantified in a prospective study with clinical MON onset during 1990-95 in Stockholm, Sweden. During a mean follow-up time of 3.8 years, the presence of MS-like brain magnetic resonance imaging (MRI) lesions and oligoclonal immunoglobulin (Ig) G bands in cerebrospinal fluid (CSF) were strong prognostic markers of CDMS, with relative hazard ratios of 4.68 [95% confidence interval (CI) 2.21-9.91] and 5.39 (95% CI 1.56-18.61), respectively. Age and season of clinical onset were also significant predictors, with relative hazard ratios of 1.76 (95% CI 1.02-3.04) and 2.21 (95% CI 1.13-3.98), respectively. Based on the above two strong predictors, individual probability of CDMS development after MON was calculated in a three-quarter sample drawn from a cohort, with completion of follow-up at three years. The highest probability, 0.66 (95% CI 0.48-0.80), was obtained for individuals presenting with three or more brain MRI lesions and oligoclonal bands in the CSF, and the lowest, 0.09 (95% CI 0.02-0.32), for those not presenting with these traits. Medium values, 0.29 (95% CI 0.13-0.53) and 0.32 (95% CI 0.07-0.73), were obtained for individuals discordant for the presence of brain MRI lesions and oligoclonal bands in the CSF. These predictions were validated in an external one-quarter sample.