Kappa-index: Real-life evaluation of a new tool for multiple sclerosis diagnosis.

The intrathecal production of oligoclonal immunoglobulin bands (OCB) is a prognostic factor for multiple sclerosis (MS) evolution in clinically isolated syndrome (CIS) patients and a diagnostic factor for MS. The kappa free light chain (K)-index represents a quantitative automated alternative to OCB. We retrospectively evaluated OCB and K-index results in 274 patients with MS (n = 48) or CIS (n = 29) at diagnosis, non-MS inflammatory central nervous diseases (n = 35), and non-inflammatory central/peripheral nervous diseases (n = 162).