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BOSTON – Age and any exposure to disease-modifying therapy were among the factors identified as independent predictors of the likelihood of conversion from clinically isolated syndrome to clinically definite multiple sclerosis in patients in a large prospective cohort study.
The findings could have important implications for treatment initiation in patients at higher risk of conversion, Dr. Tim Spelman said at a joint meeting of the Americas and European committees for Treatment and Research in Multiple Sclerosis. The logical extension of these findings would be to develop a risk calculator that considers the values for the predictors identified in this study, and that helps in the identification of patients who may benefit from closer monitoring and early treatment intervention.
Of 3,296 patients with clinically isolated syndrome 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 disease. Age was one factor found to be significantly associated with conversion; for every additional 5 years of age at the time of clinically isolated syndrome (CIS), the likelihood of relapse was reduced by 10% (hazard ratio, 0.90), Dr. Spelman said.
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), said Dr. Spelman of the University of Melbourne, Parkville, Australia.
Having at least 1 T1 gadolinium enhancing lesion on cerebral magnetic resonance imaging was associated with an increased risk of relapse, compared with having no such lesions (hazard ratio, 1.25), and having at least 1 infratentorial and at least 1 juxtacortical lesion on cerebral MRI were also associated with an increased risk of relapse, compared with having no such lesions (hazard ratios of 1.23 and 1.21, respectively).
Finally, the presence of oligoclonal bands on baseline cerebrospinal fluid examination was also 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, Dr. Spelman said.
Patients in the study were recruited from 50 clinics in 22 different countries, contributing a total of 5,379 patient years of data with more than 30,000 observation points.
Dr. Spelman reported receiving honoraria for consultancy and funding for travel from Biogen Idec.