Evaluating neurofilament light chain serum levels as a diagnostic marker for Lyme neuroborreliosis.

Serum neurofilament light chain (sNfL) is a biomarker for neuro-axonal injury. To assess sNfL's utility as a diagnostic marker for Lyme neuroborreliosis (LNB). We compared serum and CSF NfL levels in LNB patients and age-matched controls. Age-adjusted NfL values were used in receiver operating characteristic (ROC) analysis. Retrospective cohort study. Eighty-six patients (30 LNB, 29 with-, and 27 without neurological disorders) were included. Compared to individuals without neurological disease, LNB patients showed increased serum (median (interquartile range, IQR): 36.3 pg/ml (19.3-112.0) vs 20 pg/ml (12.9-37.3), p < 0.001) and CSF NfL levels (median (IQR): 1000.0 pg/ml (286.0-6471.0) vs 182 pg/ml (99.3-474.0), p < 0.001). NfL concentrations were similar in LNB and other neurological disorders. ROC analysis of age-adjusted sNfL and CSF NfL levels showed areas under the curve of 0.78 (95% confidence interval (CI): 0.66-0.89) and 0.83 (95% CI: 0.71-0.94), respectively. sNfL concentrations lack sufficient diagnostic capability for LNB diagnosis.