Inclusion Criteria:  Signed informed consent Adult patients with a documented diagnosis of SPMS with inflammatory disease activity who are going to be treated with Siponimod under routine medical care and in accordance with the Swiss label Patient willing and able to complete the questionnaires  Exclusion Criteria:  Patients treated outside of the approved Swiss label for Siponimod Prior treatment or already ongoing treatment with Siponimod Use of investigational drugs during the study, OR within 3 months before enrollment, OR within 5 half-lives of investigational drug before enrollment, OR until the expected pharmacodynamic effect has returned to baseline, whichever is longer Subjects who are not able to provide consent due to incapable judgement