A new study has found that interferon beta, the most widely prescribed drug for the treatment of multiple sclerosis, is ineffective against stopping the progression to disability for patients, the New York Times reported.

The research, out of the University of British Columbia in Vancouver, Canada, is one of only a few studies to examine the drug’s effectiveness at preventing the onset of irreversible disability. However, the medicine does help to reduce brain lesion development and the frequency of relapses.

Multiple sclerosis is an autoimmune disease that affects the central nervous system, causing damage to the protective covering of nerve cells.  The condition is characterized by periods of relapse in which patients can experience painful muscle spasms, problems with leg and arm movement and dizziness and balance problems.  While the condition is incurable, patients can expect a normal life expectancy and relatively normal day-to-day life if they manage the condition with medicine and therapy.

Interferon beta is often prescribed to treat a common form of the disease know as relapsing-remitting MS.  To analyze the drug’s effectiveness, researchers, led by Helen Tremlett, an associate professor of neurology at the University of British Columbia, collected data from 868 patients with MS who had been treated with interferon beta.  They then compared this group to 1,788 MS patients who had never taken the medicine.

According to the New York Times, the comparisons ultimately showed that patients treated with interferon beta did not have a lesser chance of suffering long-term disability than those who hadn’t taken the drug.

However, Tremlett cautioned against people discontinuing their use of interferon beta, because she said it is still useful.

“These drugs were licensed because they reduce relapse and have a better outcome with lesions,” Tremlett told the New York Times. “That has not changed.”

The study was published Tuesday in the Journal of the American Medical Association.

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