Quality Assessment in Multiple Sclerosis Therapy (QUASIMS): a comparison of interferon beta therapies for relapsing-remitting multiple sclerosis.

Interferon beta (IFN beta) preparations are the most frequently prescribed therapies for patients with relapsing multiple sclerosis (MS). Several open-label observational studies report similar efficacy among IFN beta preparations. The Quality Assessment in Multiple Sclerosis Therapy (QUASIMS) study is a large, open-label observational study designed to compare the effectiveness and tolerability of available IFN beta preparations as disease-modifying therapies for relapsing MS across a wide range of clinical practice settings. This retrospective, controlled cohort study was conducted by chart review at 510 sites in Germany, Austria, and Switzerland. Enrolled patients had received one of the four available IFN beta preparations/dosing regimens (intramuscular IFN beta-1a 30 microg 1x/week [Avonex], subcutaneous (SC) IFN beta-1a 22 or 44 microg 3 x/week [Rebif], or SC IFN beta-1b 250 microg 3.5x/week [Betaferon/Betaseron]) for >or= 2 years. Pre-planned outcomes at 1 and 2 years included change from baseline Expanded Disability Status Scale (EDSS) score, percentage of progression-free patients (< 1.0 EDSS point), annualised relapse rate (RR), percentage of relapse-free patients, and reasons for therapy change. Of 4754 evaluable patients, 3991 (84%) received IFN beta as initial therapy. There were no significant differences among IFN betas when used as initial or follow-up therapy on almost all outcome variables. Relapse rate was consistently higher and percentage of relapse-free patients consistently lower for all products used as follow-up versus initial therapy. Results of QUASIMS showed similar effectiveness among IFN beta products. Benefits were consistently superior when IFN beta was used as initial rather than follow-up therapy. Our results suggest that patients do not benefit in terms of disease outcome from switching between IFN beta preparations/dosing regimens.