BOSTON—Age and any exposure to disease-modifying therapy may independently affect the likelihood of conversion from clinically isolated syndrome (CIS) to clinically definite multiple sclerosis (MS), according to the results of a large prospective cohort study presented at the 2014 Joint ACTRIMS–ECTRIMS Meeting.
The findings could have important implications for treatment initiation in patients at higher risk of conversion, said Tim Spelman, of the University of Melbourne in Parkville, Australia. These results suggest the potential utility of developing a risk calculator that considers the values for the predictors identified in this study and helps identify patients who may benefit from closer monitoring and early treatment intervention.
Patients were recruited from 50 clinics in 22 countries, contributing a total of 5,379 patient years of data with more than 30,000 observation points.
Of 3,296 patients with CIS who were enrolled in the MSBase Incident Study (MSBASIS) subset of the MSBase global registry, 1,953 (59%) experienced a second attack, marking the conversion to clinically definite MS. Age was significantly associated with conversion to MS; for every additional five years of age at the time of CIS, the likelihood of relapse was reduced by 10%, said Mr. Spelman.
Relapse risk was also lower in patients with any exposure to disease-modifying therapy, compared with those with no such exposure (hazard ratio, 0.57), and in those with increasing proportion of follow-up time on disease-modifying therapy (hazard ratio, 0.35).
Having at least one T1 gadolinium-enhancing lesion on cerebral MRI was associated with an increased risk of relapse, compared with having no such lesions (hazard ratio, 1.25). In addition, having at least one infratentorial and at least one juxtacortical lesion on cerebral MRI also were associated with an increased risk of relapse, compared with having no such lesions (hazard ratios of 1.23 and 1.21, respectively).
The presence of oligoclonal bands on baseline CSF examination also was associated with an increased risk of relapse (hazard ratio, 1.52). Baseline spinal MRI lesion frequency was co-linear with oligoclonal banding in the CSF, said Mr. Spelman.
—Sharon Worcester