The usefulness of two CXCL13 assays on cerebrospinal fluid for the diagnosis of Lyme neuroborreliosis, a retrospective study in a routine clinical setting.

Recent studies have shown elevated levels of the B-cell chemokine (C-X-C motif) ligand 13 (CXCL13) in the cerebrospinal fluid (CSF) of patients with early Lyme neuroborreliosis (LNB). In this retrospective study, we evaluated the diagnostic performance of the Quantikine CXCL13 ELISA (R&D Systems, Inc., MN, USA) and the recomBead CXCL13 assay (Mikrogen, Neuried, Germany) for the detection of CXCL13 in CSF. All consecutive patients from whom a CSF and a serum sample had been collected between August 2013 and June 2016 were eligible for inclusion. Patients suspected of LNB were classified as definite, possible or non-LNB according to the guidelines of the European Federation of Neurological Societies (EFNS). Due to the limited number of LNB patients in the predefined study period, additional LNB patients were included from outside this period. In total, 156 patients (150 consecutive patients and six additional LNB patients) were included. Seven (4.5%) were classified as definite, eight (5.1%) as possible and 141 (90.4%) as non-LNB patients. Receiver operating characteristic (ROC) curve analysis comparing definite LNB patients with non-LNB patients showed a cut-off value of 85.9 pg/ml for the Quantikine CXCL13 ELISA and 252.2 pg/ml for the recomBead CXCL13 assay. The corresponding sensitivities were 100% (95% confidence interval [CI]: 100%-100% (for both), the corresponding specificities were 98.6% [95% CI: 96.5%-100%] for the CXCL13 ELISA, and 97.2% [95% CI: 93.6%-100%] for the recomBead CXCL13 assay, respectively. This study showed that CXCL13 in CSF can be of additional value for the diagnosis of LNB.