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Review: In relapsing-remitting multiple sclerosis, recombinant interferon reduces exacerbations in the first 2 treatment years

Jock Murray, MD
[+] Article, Author, and Disclosure Information

*Calculated from data in article.

Sources of funding: Multiple Sclerosis Society of Canada and Fondazione Italiana Sclerosis Multipla.

For correspondence: Professor G.P. Rice, University of Western Ontario, London, Ontario, Canada. E-mail grice@julian.uwo.ca.

Ann Intern Med. 2002;136(3):104. doi:10.7326/ACPJC-2002-136-3-104
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Question: In patients with relapsing-remitting multiple sclerosis (MS), is recombinant interferon more effective than placebo for reducing clinical relapse and disease progression?

Data sources: Studies were identified by searching 3 databases; hand searching references in identified trials and symposia reports (1990 to 2000); and contacting trialists and 5 drug manufacturers.

Study selection: Studies were included if they were randomized, double-blind, placebo-controlled trials of α- or β-recombinant interferons given subcutaneously or intramuscularly to patients who had a diagnosis of MS and who were in a relapsing-remitting phase (i.e., ≥ 1 exacerbation followed by complete or partial recovery).

Data extraction: Reviewers independently extracted data on participant characteristics, intervention (type of interferon, dose, duration of treatment, and follow-up), outcome measures, use of corticosteroids, need for hospitalization, side effects, and adverse events. Primary outcomes were the number of patients with exacerbations during scheduled treatment and follow-up, the number of patients whose disease progressed during the first 2 years of treatment, mean change in disability score, and the number of patients unable to walk without aid at the end of follow-up.

Main results: 7 trials (n = 1215) met the selection criteria. Overall, 240 patients (20%) were excluded after randomization or were lost to follow-up. Meta-analysis showed that patients receiving interferon had a reduced risk for new exacerbations after 1 and 2 years of treatment (Table); however, at 2 years, the result became nonsignificant when interferon-treated patients who dropped out were assumed to have had exacerbations {relative risk increase (RRI) 11%, 95% CI −27 to 68}*. Fewer patients who received interferon had disease progression over the first 2 years of treatment (Table), but this result became nonsignificant when interferon-treated patients who dropped out were assumed to have progressed {RRI 31%, CI −40 to 189}*. Patients who received interferon also had lower disability scores at 2 years than did patients who received placebo (2 trials, n = 618, weighted mean difference 0.25, 95% CI 0.05 to 0.46). No data were available for the number of patients able to walk unaided at 2 years. Patients receiving interferon had a higher risk for flu-like symptoms, fever, fatigue, nausea and vomiting, headache, injection site reactions, and hair loss (all P≤ 0.05).

Conclusion: In patients with relapsing-remitting multiple sclerosis, recombinant interferon treatment results in a modest reduction in exacerbations during the first 2 years of treatment.

Recombinant interferon vs placebo for relapsing-remitting multiple sclerosis†

Outcomes (number of trials, patients)Weighted event ratesRRR (95% CI)NNT (CI)
≥ 1 exacerbation at 1 y (5, 667)45%68%27 (3 to 45)‡5 (3 to 14)
≥ 1 exacerbation at 2 y (3, 919)56%70%20% (12 to 27)§8 (6 to 13)
Disease progression at 2 y (3, 919)20%29%31% (13 to 45)§12 (7 to 30)

†Abbreviations defined in Glossary; weighted event rates, RRR, NNT, and CI calculated from data in article.

‡Meta-analysis was done using a random-effects model.

§Meta-analysis was done using a fixed-effects model.





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