Feb. 13, 2003 -- Interferon treatments may have become the new standard of care for many multiple sclerosis (MS) patients in the last decade, but a new review of research shows little is known about the long-term effects of the popular drugs.
Researchers say the review of interferon-based treatments for relapsing remitting MS shows they slightly reduce the number of flare-ups or relapses of the disease during the first year of treatment. But the studies do not show that the drugs have are effective beyond that point.
Five drugs (Avonex, Betaseron, Copaxone, Novantrone, and Rebif) have been approved to treat MS in the U.S. The drugs are thought reduce exacerbations of the disease by slowing the immune system's attack on the nervous system that occurs in people with MS.
But researchers say it's not clear whether the drugs actually prevent disease progression or if their benefits can be sustained over time. In addition, the drugs are expensive, and some patients can't tolerate the side effects, such as flu-like symptoms and, in some cases, hair loss, blood cell abnormalities, and depression.
The study, published in the Feb. 15 issue of The Lancet, reviewed seven specific studies of recombinant interferons in MS patients that were published between 1993 and 2002. In the studies, 667 patients were followed for one year and 919 patients were followed for two years.
Researchers found that interferon seemed to reduce the number of flare-ups during the first year by 27%, but because many patients dropped out of the studies it was difficult to determine the drugs' effectiveness of reducing the flare-ups after two years of treatment.
But in those who were followed for two-years, treatment produced a 30% reduction in the risk of disease progression.
Graziella Filippini, MD, of the National Neurological Institute in Milan, Italy, and colleagues say about 20% of the patients in these studies had to be excluded from their analysis due to insufficient information.
They say future studies of interferon therapy should be better designed and include more detailed data on the nature of flare-ups that patients experience while on the drugs and how the treatment affects their overall quality of life.
SOURCE: The Lancet, Feb. 15, 2003 • WebMD Medical Reference: "Newly Diagnosed: Multiple Sclerosis."