Natalizumab vs interferon beta 1a inrelapsing-remitting multiple sclerosis: a head-to-head retrospective study.

No head-to-head study has been performed yet to assess whether natalizumab is more effective than classical immunomodulators in multiple sclerosis (MS).To retrospectively compare the efficacy of natalizumab vs IFN beta 1a SC (44 ??g; Rebif(®) ) on clinical and radiological findings in two matched cohorts of patients with MS.We retrospectively enrolled two cohorts of 42 patients (F/M: 35/7) with relapsing-remitting multiple sclerosis treated with natalizumab or IFN beta 1a for at least 12 consecutive months. Outcome measures were annualized relapse rate (ARR), changes in expanded disability status scale (EDSS) score, and number of contrast-enhancing lesions (CELs) at magnetic resonance imaging (MRI).In both groups, the ARR in the 12 months of treatment was lower than in the 12 months before therapy (0.24 vs 1.50 in natalizumab-treated group, P < 0.0000; 0.55 vs 1.10 in IFN beta 1a-treated group, P = 0.0006), being the effect of natalizumab significantly stronger (P = 0.0125). EDSS reduction was significantly different between the two groups in favor of natalizumab (P = 0.0018). The frequency and number of CELs per patient were decreased in both groups. In the second year, the treatment affected ARR and EDSS progression in the two groups of patients similarly to the first year, whereas number of CELs decreased more significantly in natalizumab group (P = 0.008).After 12 and 24 months of therapy, natalizumab was more effective than IFN beta 1a SC on both disease activity and disability progression. Prospective head-to-head studies would be helpful to further evaluate the differences observed in the MRI outcomes.