CHI3L1 and myeloid sarcoma: With the purpose of investigating the value of the combined measure in MS prognosis, we stratified patients in four groups according to both NFL and CHI3L1 values with respect to their median in the RRMS cohort in the absence of disease activity (Group 1: both NFL and CHI3L1 below median value; Group 2: high NFL; Group 3: High CHI3L1; Group 4: NFL and CHI3L1 above median values).