Click to read... The study, which is still ongoing, is labeled Quality Assessment in MS Therapy, or QUASIMS. "The goal of this study was to compare the efficacy of interferon-beta products in relapsing MS in different clinical settings throughout the world," Limmoth and his fellow investigators wrote. Patients were included in the study if they had been taking one of four interferon betas uninterrupted for at least two years. That included 30 micrograms (mcg) of Avonex (interferon beta-1a) once per week, 250 mcg of Betaseron (interferon beta-1b) once every other day, or two different doses of Rebif (interferon beta-1a): 22 mcg or 44 mcg three times per week.

"Efficacy was similar among patients treated with the four different interferon-beta preparations in different countries," the researchers wrote. "Switching between different interferon preparations did not appear to provide additional benefits."