Treatment with interferon beta (1a or 1b) was not associated with reduced progression of disability among patients with relapsing–remitting multiple sclerosis (MS), according to research published in the July 18 JAMA.
The observed outcome rates for reaching a sustained Expanded Disability Status Scale score of 6, which was the study’s main outcome measure, were 10.8% for treated patients, 5.3% for the contemporary control cohort, and 23.1% for the historical control cohort. After adjusting for potential baseline confounders such as sex, age, and disease duration, researchers found no statistically significant difference in this rate between cohorts. Further adjustment did not alter the results.
Afsaneh Shirani, MD, a postdoctoral research fellow at the University of British Columbia’s Pharmacoepidemiology in Multiple Sclerosis Research Group in Vancouver, and colleagues prospectively collected data on 2,656 patients with relapsing–remitting MS. Of these patients, 868 registered with a British Columbia clinic when interferon beta was available and underwent treatment, 829 registered during the same period but did not undergo treatment, and 959 registered before the availability of interferon beta and remained unexposed to the drug. Gender ratio and mean age of disease onset were similar for all cohorts.
“The ultimate goal of treatment for MS is to prevent or delay long-term disability,” stated Dr. Shirani and colleagues. “Our findings bring into question the routine use of interferon beta drugs to achieve this goal in MS. It is, however, possible that a subgroup of patients benefit from interferon beta treatment and that this association would not be discernable in our comprehensive ‘real-world’ study. Our findings also encourage the investigation of novel therapeutics for MS.”
“The differing directions of the hazard ratios found in these comparisons—although neither was statistically significant—are compatible with the assumption that the contemporary cohort included a high number of patients who did not qualify for treatment because their disease was relatively benign, thus introducing a bias against interferon treatment,” said Tobias Derfuss, MD, Professor of Biomedicine at University Hospital Basel in Switzerland, and Ludwig Kappos, MD, Professor of Biomedicine at the University of Basel in Switzerland, in an accompanying editorial. The study, however, “reinforce[s] the conclusion that the associations between use of interferons and long-term disability, although plausible, remain unproven,” they concluded.
Shirani A, Zhao Y, Karim ME, et al. Association between use of interferon beta and progression of disability in patients with relapsing-remitting multiple sclerosis. JAMA. 2012;308(3):247-256.
Derfuss T, Kappos L. Evaluating the potential benefit of interferon treatment in multiple sclerosis. JAMA. 2012;308(3):290-291.