Real World Analysis on Lymphocyte Reconstitution After Lymphopenia in Participants Treated by Tecfidera

The primary objective of the study is to describe absolute lymphocyte count (ALC) reconstitution after Dimethyl fumarate (DMF) discontinuation, in Relapsing-Remitting Multiple Sclerosis (RRMS) participants with lymphopenia. The secondary objectives of the study are characterization of lymphopenia in overall population; characterization of lymphopenia in participant with DMF discontinuation ; description of the evolution of ALC during DMF treatment; description of the time to reach a discontinuation of DMF treatment; exploration of the time to reach clinical outcomes (Expanded Disability Status Scale \[EDSS\] and relapse) according to lymphopenia; description of the event rate of the serious or opportunistic infections in overall population from DMF initiation and according to DMF discontinuation and lymphopenia; description of the event rate of serious and opportunistic infections in overall population from DMF initiation and according to lymphopenia; estimation of the associations between the baseline demographic and clinical characteristics and the risk to reach a lymphopenia; estimation of the associations between the baseline demographics and clinical characteristics and the risk to reach an ALC reconstitution after DMF discontinuation in participants with lymphopenia; and investigation of the changes of absolute cluster of differentiation 4 (CD4) and cluster of differentiation 8 (CD8) count in overall population on DMF if available.