In their article in the November 1998 issue of the ARCHIVES, Rice and Ebers1 raised concerns about the best method for defining disease progression for patients with relapsing-remitting multiple sclerosis (MS) in clinical trials, and they cast doubt on the significance of disability progression as defined in the pivotal interferon beta-1a (IFN-β-1a) (Avonex; Biogen Inc, Cambridge, Mass) trial.2 I would like to comment, in part because I was quoted out of context in the article.