Interferon, azathioprine and corticosteroids in multiple sclerosis: 6-year follow-up of the ASA cohort

Objective To evaluate long-term effects of 2-year treatment with interferon beta combined with low-dose azathioprine and prednisone in multiple sclerosis. Methods In the original 2-year ASA study, 181 patients with early relapsing–remitting multiple sclerosis were randomised into 3 treatment arms: those treated with interferon beta ( n =60), with interferon beta and low-dose azathioprine ( n =58), and interferon beta, azathioprine and low-dose prednisone ( n =63). Of these, 172 were included in this 4-year non-study extension. Three monthly clinical controls and annual MRI scans were carried out. The primary endpoint was annual relapse activity. The secondary endpoints were disability and quantitative MRI parameters. Results Nine patients were lost to follow-up and 172 were included in the analyses. None of relapse activity, disability accumulation or MRI parameters differed significantly between the groups over 6 years. Only 5.5% and 0.6% of patients were free from disease activity at year 2 and year 6 of the treatment initiation. Conclusion The tested combined therapeutic regimen does not improve long-term outcomes in patients with multiple sclerosis. Furthermore, interferon is not able to completely abolish disease activity.