Multiple sclerosis patients who are stable on interferon therapy show better outcomes when staying on same therapy than patients who switch to another interferon

BACKGROUND: Real-world outcomes from staying on an interferon beta (IFNβ) vs switching to another IFNβ could help guide treatment decisions. This study’s objective was to compare outcomes of stable multiple sclerosis (MS) patients on an IFNβ who stayed on therapy vs those who switched to another IFNβ. METHODS: MS patients were identified from the Optum Insights Clinformatics Data Mart Multi-Plan who were 18–64 years old and relapse-free (stable) over 1 year while continuously being treated with an IFNβ. Patients were propensity score matched 3:1 using age, gender, initial IFNβ, adherence, and month and year for patients who stayed on the initial IFNβ (No Switch) to patients who switched to another IFNβ (Switch). Patients had to be continuously enrolled for 1 year prior to and 1 year after the index date (date of the first claim of the switched-to IFNβ or the match date when continuing on initial IFNβ treatment). Patients were enrolled with index dates between January 1, 2005 and September 30, 2014. Relapses were recorded during the 1-year follow-up period after index date. RESULTS: After matching, there were 381 patients in the Switch group and 1,143 in the No Switch group. Baseline characteristics were well matched between groups (average age 46 years, 72% female). The percentage of patients experiencing a relapse during the follow-up was significantly higher in the Switch group than in the No Switch group (21% vs 12%, P<0.0001). Annual relapse rate during the follow-up was significantly higher in the Switch group than in the No Switch group (0.35 vs 0.20, P<0.0001). CONCLUSION: MS patients stable on IFNβ therapy who remain on initial therapy had significantly better outcomes (lower annual relapse rate and percentage of patients with relapses) than patients who switched to another IFNβ. This supports the benefits of allowing patients to remain on current IFNβ therapy when stable.