Interferon Treatment Delays Multiple Sclerosis

The drug, interferon beta-la (Avonex), is already used to treat patients with established multiple sclerosis but has never been used earlier in the course of the disease. The study, published in The New England Journal of Medicine (2000;343:898-904), was conducted at 50 hospitals in the United States and Canada.

The study involved 383 patients who had exhibited one symptom of multiple sclerosis. Following initial treatment with corticosteroids, 193 patients were randomly assigned to receive weekly intramuscular injections of interferon beta-la while the other 190 patients were assigned to receive weekly injections of placebo. Over three years, 46 patients in the interferon beta-la group developed multiple sclerosis, compared to 76 in the placebo group. The drug was well tolerated and its effects were rapid and sustained, with no serious adverse effects. Because the results of the study were so positive, the trial was stopped early to offer patients in the placebo group the benefits of treatment.

Patients are considered at risk for developing multiple sclerosis when they have neurologic symptoms that do not meet the strict definition of the disease but are known to precede it. Such symptoms include optic neuritis and incomplete transverse myelitis.