Background It is unclear whether recombinant β interferons (IFNβ) can be effective in secondary progressive multiple sclerosis (SPMS). The aim was to determine whether IFNβ can reduce the risk of disability and cognitive impairment progression in SPMS.

Methods Using Cochrane methodology, we reviewed all randomised placebo controlled trials of IFNβ in SPMS patients (1995–March 2012).

Results 5 trials (3082 patients) were included. After 3 years, interferons did not reduce disability progression, confirmed at 6 months (RR 0.98, 95% CI 0.82 to 1.16). A small reduction in the number of patients who had relapses during the first 3 years of treatment (RR 0.91, 0.84 to 0.97) was found. No analysis of cognitive data was possible. More treated than placebo patients dropped out for adverse events.

Conclusion 3 year treatment with IFNβ does not delay permanent disability in SPMS but reduces relapse risk, indicating that the anti-inflammatory effect of IFNβ is unable to prevent MS progression once it has become established.