Multiple sclerosis: Patients unsettled according to study - but interferon therapy remains indispensable

16.08.2012 19:17

Interferon preparations are used as standard therapy for multiple sclerosis (MS). In the past, several studies have shown that these drugs reduce inflammatory activity in the central nervous system. However, the influence on the progression of the disability, i.e. whether patients are dependent on walking aids or a wheelchair, has not yet been convincingly proven to be positive or negative. To investigate this question, scientists from Canada evaluated material from patient databases. They came to the conclusion that interferon therapy does not slow down the progression of disability. This news has unsettled many patients, but upon closer inspection the study has major methodological weaknesses: “From the perspective of the MS Competence Network, the German Society for Neurology (DGN) and the Medical Advisory Board of the German MS Society, there is currently no reason for this work “To change the current treatment and recommendation practice with interferon preparations,” says Prof. Dr. Heinz Wiendl, director of the clinic and polyclinic for neurology, inflammatory diseases of the nervous system and neuro-oncology at the Westphalian Wilhelms University of Münster. “We therefore appeal to all MS patients not to stop their interferon treatment,” said the neurologist. This study also does not indicate a need for changes to the MS guidelines published in the spring.

The Canadian scientists compared 2,556 patients who were divided into a treated with various interferon preparations, an untreated and a "historical" comparison group before the introduction of the drug. The follow-up period was approximately 5 years. It is precisely this backward evaluation of the data that represents the methodological weakness: “It is difficult to compare with a group of patients who may have a lower level of inflammation and disability. The comparison with the untreated control group is also imprecise, as there could be some patients among these patients who are not suitable for therapy with interferons.” In science, this is referred to as a so-called selection bias, i.e. the results of the study are based on pre-selection distorted.

The authors tried to limit this bias by including control values such as gender, age, duration of illness and degree of disability in the calculation. “Nevertheless, in the absence of evidence of a positive therapy effect, the opposite cannot be scientifically derived from the study design,” says Professor Wiendl. Furthermore, it is questionable whether the relatively short follow-up period is sufficient to assess the long-term effect of the drug.

Professor Hans-Christoph Diener from the German Society for Neurology also points out the following in this context: “It is scientifically questionable when data from observational studies are compared with data from large and properly conducted randomized placebo-controlled studies. Non-randomized observations are only permitted where there are no findings from randomized studies.” In addition, long-term studies have clearly proven the effectiveness of beta-interferon, says Professor Diener.

Note to the media
Press conference with an “Update Multiple Sclerosis” on Friday, September 28, 2012, from 10 a.m. to 11 a.m. in the CCH Hamburg at the annual meeting of the German Society for Neurology. www.dgn.org/presse

literature
Shirani A et al.: Association Between Use of Interferon Beta and Progression of Disability in Patients With Relapsing-Remitting Multiple Sclerosis. JAMA, 2012, 308: 247-256