Interferon Beta for Primary Progressive Multiple Sclerosis

Background Therapeutic trials with beta-interferon in Multiple Sclerosis (MS) have mainly focused on remitting-relapsing multiple sclerosis (RRMS), demonstrating a reduction in relapse rate. However, there is not enough evidence about their efficacy in patients with primary progressive multiple sclerosis (PPMS). Objectives Identify and summarize the evidence that beta-interferon is beneficial and safe in patients with PPMS. Search strategy We searched (until April 2008) the Cochrane MS Group Trials Register; The Cochrane Central Register of Controlled Trials (CENTRAL) The Cochrane Library, (2008, Issue 3,); MEDLINE (PubMed) (January 1966 to April 2008), EMBASE (January 1974 to April 2008); NICE (January 1999 to April 2008); LILACS (January 1986 to April 2008); Screening of reference lists of all primary studies found; Contact and inquiry of drug manufactures and multiple sclerosis experts. Selection criteria Randomized double or single blind, placebo-controlled trials of recombinant beta-interferon in patients with PPMS including trials of MS which report separate outcomes in subgroups of patients with PPMS. Data collection and analysis Two reviewers independently extracted and assessed trials' quality according to the criteria outlined in The Cochrane Handbook. Main results Of 1280 potential studies evaluated, only two Randomized Control Trials (123 patients) were included. beta-interferon treatment compared to placebo did not show differences regarding the proportion of patients with progression of the disease (RR 0.89, 95% CI 0.55 to 1.43), and it was associated with a greater frequency of treatment-related adverse events (RR 1.90, 95% CI 1.45-2.48). One of the trials evaluated the MRI secondary outcome pre-specified in the protocol. This trial showed that at two years the numbers of active lesions on brain MRI scan in beta-interferon arm were significantly lower than in placebo arm (weighted mean difference -1.3, 95% CI -2.15 to -0.45, P = 0.003); also, the number of participants with active lesions was significantly higher in placebo arm vs. beta-interferon arm at two years (RR 0.43, 95% CI 0.22 to 0.86, P = 0.02). Authors' conclusions Limited data on the effect of beta-interferon treatment on PPMS exists. Only two single-centre placebo controlled trials of interferon beta have been done. Based on this review, the included studies showed that beta-interferon treatment was not associated with reduced disability progression in PPMS patients. However, the trial population was too small to allow definitive conclusions on the efficacy of beta-interferon therapy in PPMS patients. Larger research studies need to be done in patients with PPMS in order to clarify whether beta-interferon is effective in this population.