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MS Drug Interferon Beta May Not Slow Progression

Interferon beta, a group of widely-prescribed drugs for treating multiple sclerosis (MS), may not slow long-term progression of the disease, according to a new study of patients with relapsing-remitting MS that is due to be published this week in the Journal of the American Medical Association, JAMA.

Afsaneh Shirani, of the University of British Columbia (UBC), Vancouver, Canada, and colleagues concluded there was no strong evidence that interferon beta had a measurable impact on the long-term disability progression of MS.

They compared patients treated with interferon beta to untreated patients and found, after taking into account possible influencing factors, the treated patients were no less likely to progress to the point where they needed a cane to walk 100 metres, a key measure of disease progression. Relapsing-Remitting MS Relapsing-remitting multiple sclerosis is the most common form of MS, affecting about 85% of Canadians with MS. It is a form of MS where patients have relapses or "flare-ups" during which new symptoms can appear or old ones can come back or worsen. The relapses are followed by periods of remission during which patients can partially or even fully recover.

Corresponding author of the JAMA study Helen Tremlett is a professor at UBC and holds the Canada Research Chair in Neuroepidemiology and Multiple Sclerosis at UBC. She told the press the study gives patients and doctors additional information about the longer term effects of interferon beta.

"We know that this class of drugs is very helpful in reducing relapses, which can be important to patients. We do not recommend that patients stop taking these medications, but these findings provide evidence, allowing more realistic expectations as to the anticipated benefits associated with drug treatment from the disability perspective."

Study Compared Treated and Untreated MS Patients In their background information the authors note that:

"A key feature of MS is clinical progression of the disease over time manifested by the accumulation of disability. Interferon beta drugs are the most widely prescribed disease-modifying drugs approved by the US Food and Drug Administration for the treatment of relapsing-onset MS, the most common MS disease course."

But, they explain, there aren't enough studies that follow the effect of interferon beta on patients in the long term.

For their study, Shirani and colleagues examined linked health records of 2,656 British Columbia (BC) patients between 1985 and 2008 in a retrospective cohort study: that is the data had already been collected, anonymized and linked together. The data came from a number of sources, including the BC Ministry of Health, PharmaNet and the BC Multiple Sclerosis (BCMS) databases.

The records included 868 relapsing-remitting MS patients treated with interferon beta, and 829 untreated contemporary MS patients, plus 959 "historical" untreated MS patients (historical meaning they entered the study much earlier than the other two contemporary groups and predate approval of interferon beta).

The primary outcome measure of the study was the time between eligibility for treatment with interferon beta (the baseline of the study), to when the patients scored a 6 on the Expanded Disability Status Scale (EDSS). The EDSS has a range of 0 to 10, with higher scores indicating more disability: a score of 6 is when the patient requires a cane to walk 100 meters.

The follow-up period (the time that elapsed between the first and the last EDSS measurement) differed between the groups. It was much longer for the historical untreated group (the midpoint or median of their follow-up period was 10.8 years). The median follow up times for the contemporary groups were 5.1 years for the treated MS patients and 4.0 years for the untreated MS patients.

The researchers expressed the outcome measures in terms of the percentage of patients in each group that reached a sustained EDSS score of 6 during the follow up. A sustained score was one that showed no change when repeated at least 150 days later.

10.8% of the treated MS patients reached this point, compared to 5.3% of the untreated contemporaries, and 23.1% of the historical untreated group.

The researchers write that:

"After adjustment for potential baseline confounders (sex, age, disease duration, and EDSS score), exposure to interferon beta was not associated with a statistically significant difference in the hazard of reaching an EDSS score of 6 when either the contemporary control cohort or the historical control cohort were considered."

There was no change even after they adjusted, where possible, to account for socioeconomic status and co-exisiting illnesses. Conclusions Question the Use of Interferon Beta to Delay MS Progress Shirani and colleagues conclude:

"... we did not find evidence that administration of interferon beta was associated with a reduction in disability progression in patients with relapsing-remitting MS."

They suggest their findings question the use of interferon beta drugs to prevent or delay long-term disability in MS patients.

However, they also note it may be possible that some groups of MS patients may benefit from treatment with interferon beta, and this was not apparent from their analysis.

"Further work is needed to identify these potential patients; perhaps through pharmacogenomic or biomarker studies, paving the way for a tailored, personalized medicine approach. Our findings also encourage the investigation of novel therapeutics for MS," they add.

In an accompanying JAMA editorial, Tobias Derfuss and Ludwig Kappos, of University Hospital Basel, Switzerland, write that the "rigorously collected data of Shirani and colleagues reinforce the conclusion that the associations between use of interferons and long-term disability, although plausible, remain unproven".

They agree with the authors that "more effective treatment options and better criteria that lead to more accurate selection of patients who might best respond to these treatments are needed", adding that:

"The relatively low progression rate in the untreated contemporary cohort is reassuring because it indicates that despite the unreliable explicit prognostic criteria, neurologists and patients in British Columbia seem to have made the right choices."

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