Clinical characteristics of responders to interferon therapy for relapsing MS.

Objective: To determine the proportion of patients with multiple sclerosis (MS) who respond to interferon-beta (IFNB) therapy and assess whether clinical characteristics differ in IFNB responders vs nonresponders.

Methods: Data on all patients who received IFNB who were entered in the prospective European Database for Multiple Sclerosis (EDMUS) database in Lyon as of March 31, 2001, were reviewed. Responders were defined as having a lower relapse rate on IFNB compared with the year or 2 years prior to IFNB therapy.

Results: Two hundred sixty-two patients with relapsing MS received at least 6 months of IFNB: 200 relapsing remitting (RR) and 62 relapsing secondary progressive (SP). One-third of patients experienced a higher or identical annual relapse rate while on IFNB treatment. Compared with nonresponders, responders were older and had longer disease duration at the time IFNB was initiated. RRMS responders also had a higher relapse rate during the year prior to IFNB therapy and SPMS responders had a higher Disability Status Scale score at initiation of IFNB.

Conclusion: Clinical profiles of patients with relapsing MS who respond to IFNB may differ from those who do not with a more inflammatory and less neurodegenerative disease at the time IFNB is initiated.