"Adherence is a critical component in chronic disease treatment, directly impacting long-term efficacy. The GAP study suggests that AVONEX leads to superior adherence which may contribute to long-term effectiveness," said Bernd Kieseier, MD, Professor of Neurology, Heinrich-Heine-Universität, Düsseldorf, Germany, and a lead investigator in the project.
While the first half of the above statement cannot be argued with, i.e., in order for a treatment to be effective its dosing regimen must be adhered to, the second half of the above statement seems like too big of a logistical leap and is based on assumption. Although I have not read the original study, the news article does not discuss effectiveness. It only discusses adherence. One would need to compare the long term effectiveness of particular treatments in order to make the second statement. If the study had done that, then I'm sure they would be reporting that information though they don't.