Scoring the 10-year risk of ambulatory disability in multiple sclerosis: the RoAD score.

BACKGROUND Both baseline prognostic factors and short-term predictors of treatment response can influence the long-term risk of disability accumulation in patients with relapsing-remitting multiple sclerosis (RRMS). OBJECTIVE To develop and validate scoring system combining baseline prognostic factors and one-year variables of treatment response into a single numeric score predicting the long-term risk of disability. METHODS We analyzed two independent datasets of patients with RRMS who started Interferon Beta or Glatiramer Acetate, had an Expanded Disability Status Scale (EDSS) score <4.0 at treatment start and were followed for at least 10 years. The first dataset ("training set") included patients attending three MS Centers in Italy and served as framework to create the so-called RoAD score (Risk of Ambulatory Disability). The second ("validation set") included a cohort of patients followed in Barcelona, Spain, to explore the performance of RoAD score in predicting the risk of reaching an EDSS score≥6.0. RESULTS The RoAD score, derived from the training set (n = 1,225), was based on demographic (age) and clinical baseline prognostic factors (disease duration, EDSS) and one-year predictors of treatment response (number of relapses, presence of gadolinium-enhancement and new T2 lesions). The best cut-off score for discriminating patients at higher risk of reaching the disability milestone was ≥4. When applied to the validation set (n = 296), patients with a RoAD score ≥4 had an approximately 4-fold increased risk for reaching the disability milestone (p<0.001). DISCUSSION We propose the RoAD score as an useful tool to predict individual prognosis of patients with RRMS to optimize treatment strategy.