SUMMARY
- Researchers in Canada looked at real-world safety experiences related to the use of interferons in people with relapsing-remitting MS. Earlier studies have established the benefits of interferon treatment for relapsing forms of MS.
- Results confirmed some previously identified side effects, and also uncovered a possible increase in the likelihood of stroke (a 1.8-fold increase). However, the incidence of stroke overall was less than 5% over 8 years of follow-up, regardless of whether a person had taken interferons.
- The team also found a decrease in the likelihood of bronchitis and upper respiratory infections.
- These findings do not prove that interferons cause stroke or the other adverse events, but only indicate that those who experienced these events were more likely to have been exposed to interferons than those who did not experience them.
- “We still feel that overall, these drugs have an acceptable safety profile, but research like this enables healthcare professionals and patients to have a better insight into the risk-benefit profile of these medications,” noted lead investigator Dr. Helen Tremlett (University of British Columbia).
- The study, funded by the Canadian Institutes of Health and the National MS Society (USA), was published early online in Neurology on May 12, 2017.
DETAILS
Background: Forms of interferon beta have been used as
disease-modifying therapies for MS since the first – Betaseron® (interferon beta-1b) – was introduced in the U.S. in 1993, followed by Avonex® and Rebif® (interferon beta-1a). The original clinical trials showed benefits, leading to their approval. The trials also identified some potential side effects such as flu-like symptoms, elevated liver enzymes, injection-site reactions, and reductions in blood levels of immune cells (leukopenia, lymphopenia). However, clinical trials usually last only a few years, so it takes real-world use to fully understand the safety of therapies in the general population of people with MS.
The Study: To understand the real-world safety experiences related to interferons, researchers across Canada including Helen Tremlett, PhD, and Hilda de Jong, PhD (University of British Columbia) analyzed health data from the British Columbia MS database and other sources. They investigated health outcomes for people with relapsing-remitting MS who had been prescribed interferon beta between 1995 and 2004. The average length of follow-up was 8 years. Of 2,485 people included in the study, 1,031 had been treated with an interferon. The researchers compared their outcomes with people with MS who were not taking interferons.
Results: Previously reported side effects such as migraine headache, leukopenia and lymphopenia, were confirmed. This study also uncovered a possible increase in the likelihood of stroke (a 1.8-fold increase), but the incidence of stroke overall was less than 5% over 8 years of follow-up, regardless of whether a person had taken interferons. The team also reported a decrease in the likelihood of bronchitis and upper respiratory infections. In this study the previously reported risk of depression was increased by 1.3, but only during the first two years of interferon therapy.
The researchers note that they were not able to take into account all other potential contributors to the individuals’ health outcomes, including health behaviors, adherence to medication, family history and lifestyle factors.
The study, funded by the Canadian Institutes of Health and the National MS Society (USA), was published early online in
Neurology on May 12, 2017.
Comment: This study provides important real-world data related to health outcomes in people who had been treated with interferons for relapsing-remitting MS. These findings do not prove that interferons cause stroke or the other adverse events, but only indicate that those who experienced these events were more likely to have been exposed to interferons than those who did not experience them. Alternate explanations might be that one or more risk factors for any of the adverse events make it more likely for people to be on an interferon. This study was focused on real-world safety experience. Earlier studies have established the benefits of interferon treatment for relapsing forms of MS.
In a comment about their findings, project leader Dr. Helen Tremlett noted, “We still feel that overall, these drugs have an acceptable safety profile, but research like this enables healthcare professionals and patients to have a better insight into the risk-benefit profile of these medications.”
Early and ongoing treatment with disease-modifying therapy is supported by the MS Coalition, which includes the National MS Society.
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Betaseron is a registered trademark of Bayer
Avonex is a registered trademark of Biogen, Inc.
Rebif is a registered trademark of EMD Serono, Inc.