The present disclosure relates to the field of diagnostics, specifically, to a method of identifying progressing multiple sclerosis (MS) in a subject. At least one performance parameter is determined from a dataset of activity measurements obtained from the subject using a mobile device, and the performance parameter is compared to a reference, whereby a subject with progressing MS will be identified. Also disclosed is a method of recommending an anti-CD20 antibody therapy against MS that includes the steps just mentioned and the further step of recommending the anti-CD20 antibody therapy if the subject suffers from progressing MS. Also disclosed is a mobile device having a processor, at least one sensor and a database as well as software which is tangibly embedded to the device and, when running on said device, carries out the method of this disclosure as well as the use of such a device for identifying a subject suffering from progressing MS.