RT Journal Article SR Electronic T1 Clinical effectiveness of different natalizumab interval dosing schedules in a large Italian population of patients with multiple sclerosis JF Journal of Neurology, Neurosurgery & Psychiatry JO J Neurol Neurosurg Psychiatry FD BMJ Publishing Group Ltd SP jnnp-2020-323472 DO 10.1136/jnnp-2020-323472 A1 Clara Grazia Chisari A1 Luigi Maria Grimaldi A1 Giuseppe Salemi A1 Paolo Ragonese A1 Pietro Iaffaldano A1 Simona Bonavita A1 Maddalena Sparaco A1 Marco Rovaris A1 Alessia D'Arma A1 Alessandra Lugaresi A1 Maria Teresa Ferrò A1 Paola Grossi A1 Alessia Di Sapio A1 Eleonora Cocco A1 Franco Granella A1 Erica Curti A1 Vito Lepore A1 Maria Trojano A1 Francesco Patti A1 , YR 2020 UL http://jnnp.bmj.com/content/early/2020/10/14/jnnp-2020-323472.abstract AB Introduction Natalizumab (NTZ) is one of the most effective treatment options for multiple sclerosis (MS) treatment. Our study aimed to evaluate the effectiveness of NTZ when administered according to the extended dosing strategy compared with standard 4-weekly administration in a large Italian MS population.Materials and methods This retrospective multicentre study included patients with relapsing-remitting MS (RR-MS) who received NTZ administrations between the 1 June 2012 and the 15 May 2018 and were followed by the ‘Italian MS Register’. All patients with MS were stratified into two groups based on NTZ administration schedule: standard interval dosing (SID) patients who received infusions on average from 28 to 32 days (median 30) and extended interval dosing (EID) including patients who have been infused with interval between 33 and 49 days (median 43). Clinical data were assessed at baseline (before starting NTZ), after 12 (T1) and 24 months (T2) of treatment.Results Out of 5231 patients with RR-MS screened, 2092 (mean age 43.2±12.0, 60.6% women) were enrolled. A total of 1254 (59.9%) received NTZ according to SID, and 838 (40.1%) according to EID. At 12 and 24 months, no differences in terms of annualised relapse rate and disability status were found between the two groups. Progression index and confirmed disability worsening were similar between the two groups.Discussion The use of NTZ with an extended interval schedule showed similar effectiveness compared with SID. Unchanged clinical efficacy of EID schedule may raise the question of a possible advantage in terms of tolerability and safety.