Stopping Interferon Beta 1b Does Not Influence the Risk of Disability Accrual in Non-Active SPMS: Results from an Italian Real-World Study

Background: No consensus exists on the possibility to stop disease modifying therapies (DMTs) in Secondary Progressive Multiple Sclerosis (SPMS). Methods: The primary outcome was the time to reach 24-weeks confirmed Expanded Disability Status Scale (EDSS) 7.0. We enrolled all patients with a confirmed diagnosis of non-active SPMS (here, absence of clinical or radiological activity for at least 24 months before the conversion) between 1 January 2010 and 31 December 2015, at MS centers of Catania and Foggia, Italy. Patients were divided into two groups, according to the shared decision to stop DMTs (group A) or to maintain/switch to licensed interferon beta 1b for SPMS (group B). A Cox model adjusted with an inverse probability weighted propensity score (IPTW-PS) was employed. Results: A cohort of 311 patients was enrolled, 165 were in group A and 146 were in group B. Patients in the two groups were similar for baseline characteristics. The IPTW-PS adjusted Cox model for the event time to 24-weeks confirmed EDSS 7.0 did not show differences between the two groups (ExpB 0.96, CI 0.739-1.271, p = 0.819). Conclusions: In a real-world setting, in patients with non-active SPMS, the maintaining or switching to the licensed interferon beta 1b did not reduce the risk of reaching confirmed EDSS 7.0.