Response to treatment with interferon beta in patients with multiple sclerosis. Validation of the Rio Score

Introduction. Different criteria have been proposed for the response to treatment with interferon beta, and the Rio Score is one of the most widely used. The aim of this study was to validate the usefulness of the Rio Score in an independent cohort. Patients and methods. A multi-centre, prospective, longitudinal study was conducted on patients with relapsing-remitting multiple sclerosis treated with interferon beta. The patients were classified according to the presence of attacks, active lesions (new in T-2 or gadolinium enhancing lesions) in magnetic resonance imaging, a confirmed increase in disability or combinations of these variables (attacks, increase on the Expanded Disability Status Scale and active lesions) after one year's treatment. Regression analysis was used in order to identify the response-predicting variables after a three-year follow-up. Results. The sample consisted of 249 patients with relapsing-remitting multiple sclerosis. The logistic model confirmed that the presence of two (odds ratio = 6.6; CI 95% = 2.7-16.1; p < 0.0001) or three (odds ratio = 8.5; CI 95% = 1.6-46; p < 0.01) positive variables during the first year of treatment were indicative of a significant risk of activity (attacks or progression) in the next two years. Conclusions. The usefulness of the Rio Score is confirmed, in an independent cohort, as a means of identifying patients with a higher risk of developing clinical activity or progression of disability during treatment with interferon beta.