Multiple sclerosis (MS) is a chronic disease for which there is currently no proven cure. Nevertheless, desperate views have changed to substantial optimism over recent years, as several lines of evidence have indicated that disease-modifying drugs (DMDs) have beneficial effects on neurological deterioration in MS. However, assessing the success of DMD therapy in an individual patient may not always be clear-cut for the doctor. In order to address this issue, an International Working Group of doctors experienced in treating patients with MS convened to discuss the optimization of DMD therapy, and the outcome of this consensus meeting is reported here. Participants developed statements that classify changes in relapses, disease progression and brain magnetic resonance imaging in a patient with MS who is taking DMD therapy, according to whether they are worthy of note, of some concern, or of serious concern and requiring a reassessment of current therapy. Based on these statements, the performance of standardized examinations to document changes in the disease enables a visual measure of the progress of an individual patient to be built up on an analogue model. This model provides a useful framework to help the neurologist to identify those patients for whom the therapeutic options should be reconsidered.