Randomized controlled trial of interferon-beta-1a in secondary progressiveMS - Clinical results

Background: The beneficial effect of interferon beta on exacerbations in re lapsing-remitting MS has been demonstrated repeatedly, but results concerni ng disability vary. Objective: This multicenter, randomized, parallel-group , placebo-controlled study tested two doses of interferon beta-la in patien ts with secondary progressive MS, which may include relapses but is dominat ed by accumulating disability. Methods: A total of 618 patients received su bcutaneous placebo or interferon beta-1a, 22 or 44 mug three times weekly f or 3 years. Patients were assessed every 3 months. Results: The primary out come, time to confirmed progression in disability, was not significantly af fected by treatment (hazard ratio, 0.83; 95% CI, 0.65 to 1.07; p = 0.146 fo r 44 mug versus placebo). Relapse rate was reduced from 0.71 per year with placebo to 0.50 per year with treatment (p < 0.001 for both doses). Signifi cant treatment effects were seen on other exacerbation-related outcomes and on a composite measure incorporating five separate clinical and MRI outcom es. The hazard ratio for time to progression for the combined interferon be ta-la groups compared with placebo was 0.74 among patients reporting relaps es in the 2 years before study (p = 0.055), and 1.01 for those without pres tudy relapses (p = 0.934), An unexpected treatment-by sex interaction favor ed women. The drug was well tolerated. Conclusions: Treatment with interfer on beta-la did not significantly affect disability progression in this coho rt, although significant treatment benefit was observed on exacerbation-rel ated outcomes. Exploratory post hoc analyses suggested greater benefit in w omen and in patients who had reported at least one relapse in the 2 years b efore the study.