Switching IFN-Beta Therapy When Stable Raises Risk of MS Relapse


Based on the findings, patients who are stable on their current IFN-ß therapy should remain on that therapy, but further studies are needed on when to switch therapies in multiple sclerosis.

Dr Ning Wu

Ning Wu, PhD

According to a new analysis, patients with multiple sclerosis (MS) who have been relapse-free on interferon-beta (IFN-ß) therapy are significantly more likely to experience relapses when they switch to another IFN-ß than those who don’t switch.1

In this analysis of 1524 patients with MS from the Optum Insights Clinformatics Data Mart Multi-Plan, 21.26% of the group who switched IFN-ß therapy experienced a relapse in the year following the switch compared to 11.72% of those who did not switch (P <.0001). The difference was 82% higher for those who switched therapies.

“Patients who remained on their initial IFN-β therapy had 45% lower odds of experiencing a relapse and a 43% lower annual relapse rate than those patients who switched to a different IFN-β therapy,” coauthor Ning Wu, PhD, and colleagues noted. The annual relapse rate was 75% higher in the Switch group (0.35 per patient-year) compared to the No Switch group (0.20 per patient-year; P <.0001).

Wu and colleagues acknowledge that the reasons for switching from one IFN-ß therapy to another can include multiple factors, such as suboptimal response, poor adherence, disability progression, or even formulary alterations from an insurer. Additionally, a debate has recently surfaced regarding a decline in cognitive function as a clinically valid reason for switching MS treatment.2,3

Although, the authors note that not only could a switch potentially introduce clinical events but can also infer cost issues for the patient.

“The costs of moderate to severe relapses (such as those reported in this study) are high. Goldberg et al. reported an average cost of relapses in the US of $2,381 for moderately severe and $16,589 for severe relapses (weighted average $6,834 in 2008 dollars),” they wrote. “Given these costs and the higher risks of relapse in patients who are switched, formulary decision-makers need to evaluate the trade-offs of any potential cost savings of switching stable patients.”

A subgroup analysis was also performed, which compared the percent of patients relapsed and annual relapse rates between the Switch (n = 381) and No Switch (n = 1143) groups.

These subsets included patients who were on IFN-β1a intramuscular (IM; switch, 267 patients; no switch, 801 patients), IFN-ß1a subcutaneous (SC; switch, 53 patients; no switch, 159), and IFN-ß1b SC (switch, 61; no switch, 183). The IFN-β1a SC and IFN-β1b SC subgroups were considered too small to include in the subanalyses.

“The subset of patients [who were] stable on IFN-β1a IM who remained on therapy had similar results to the overall selected population, showing significantly better outcomes than those who switched to another IFN-β,” Wu and colleagues wrote.

In the subgroup of patients who stayed on IFN-β1a IM, 113% more patients relapsed when they switched from IFN-β1a IM to another IFN-β than those who did not switch (23.22% vs. 10.99%; P <.0001). Similarly, the annual relapse rate was twice as high in the Switch group (0.40 vs 0.20 relapses per patient-year; P <.0001) in the subgroup.

There are currently 4 available IFN-ß injectable therapies for MS in the United States: SC IFN-ß1b (Betaferon/Betaseron, Bayer; Extavia, Novartis), SC IFN-β-1a (Rebif, EMD Serono), and IM IFN-β-1a (Avonex, Biogen). As well, the SC pegylated form of IFN-ß1a, peginterferon β-1a (Plegridy, Biogen) is also available.

Wu and colleagues explained that all of these therapies “have comparable efficacy with respect to relapse rates and favorable safety profiles and are well tolerated,” and that “a continuous use of IFN-βs over the course of years can benefit long-term patient outcomes by reducing the number and frequency of relapses and possibly delaying disease progression.”

They concluded that these findings suggest that patients who are stable on their current IFN-ß therapy should remain on that therapy and that further studies are required to better comprehend when to switch therapies.


1. Chen C, Wu N, Watson C. Multiple sclerosis patients who are stable on interferon therapy show better outcomes when staying on same therapy than patients who switch to another interferon. Clinicoecon Outcomes Res. 2018;10:723-730. doi: 10.2147/CEOR.S163907

2. Weinstock-Guttman B, Eckert S, Benedict RH. A decline in cognitive function should lead to a change in disease-modifying therapy - Yes. Mult Scler. 2018;24(13):1681-1682. doi: 10.1177/1352458518783364

3. Portaccio E. A decline in cognitive function should lead to a change in disease-modifying therapy - No. Mult Scler. 2018;24(13):1683-1684. doi: 10.1177/1352458518783357

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