Predictors and Conversion Rate of Clinically Isolated Syndrome to Clinically Definite Multiple Sclerosis: A Follow-up Study in Patients Living in the Southern Part of Iran

Clinical course of Clinically Isolated Syndrome (CIS) is variable, and identifying patients who will eventually develop Multiple Sclerosis (MS) is essential.

To assess the conversion rate of CIS to Clinically Definite Multiple Sclerosis (CDMS) and its predictors in southern Iran.

A total of 143 CIS patients registered to Fars Multiple Sclerosis Society (FMSS) were enrolled in the study from 2006 until 2012, and all of them were followed for 5 years. Also, their demographic and MRI data were recorded. The obtained data were analyzed by univariate and multivariable Cox regression models in SPSS v. 17. P<0.05 was considered statistically significant.

About 26.6% of patients progressed to MS after a mean duration of 3.4±1.1 years. The conversion rate was 27.6% in patients presented with optic neuritis, and 25.6% in patients presented with spinal cord problems. Although it was not statistically significant (P=0.23), the mean age of the patients who converted to MS was lower at the onset of the presentation (27.6 vs. 29.4 years). In patients who had 3 or more MRI lesions, the conversion rate was 49.2%; however, it was only 9.8% in subjects who had fewer than 3 lesions (OR=8.95, 95% CI=3.69–21.7, P <0.001). Women had higher conversion rate though it was not statistically significant (OR=2.09, 95% CI=0.57–7.64, P=0.26).

Our results supported this supposition that the number of MRI lesions at baseline can be used as a predictor of CIS conversion to MS.