Long Term Study of Avonex Therapy Following a First Attack of Multiple Sclerosis

The CHAMPS study determined that immediate initiation of interferon beta 1a therapy (AVONEX) immediately following a first clinical demyelinating event in high risk patients (i.e. those with at least 2 asymptomatic white matter lesions on cranial MR imaging \> 3 mm in diameter or ovoid) delayed the development of clinical definite Multiple Sclerosis (CDMS)(as defined by a second, clinically verifiable attack involving another part of the central nervous system) over 2 years of observation and significantly decreased the development of new or enlarging white matter lesions on MRI over 18 months (see reference). The current study is a long term extension of a cohort of CHAMPS study site and participants. The three main aims of the study are as follows: 1. To determine the long term neurological outcome in patients treated with interferon beta 1a (AVONEX) from onset of a first clinical demyelinating event 2. To determine if immediate initiation of AVONEX therapy (the CHAMPS Avonex treatment group) confers long term benefits compared to delayed initiation of therapy (the CHAMPS placebo group) on the rate of development of CDMS, annualized relapse rates, the development of permanent disability and MR measures of disease activity and progression. 3. To determine predictors of long term disease activity and disability in patients following a first clinical demyelinating event