Interleukin 8, a Biomarker to Differentiate Guillain-Barre Syndrome From CIDP

Objective To determine whether CSF interleukin 8 (IL-8) concentration can help to distinguish Guillain-Barre syndrome (GBS) from chronic inflammatory demyelinating polyneuropathy (CIDP) at the initial stage of the disease. Methods We performed retrospective immunoassay of IL-8 in CSF, collected at the University Hospitals of Geneva between 2010 and 2018, from patients diagnosed with GBS (n = 45) and with CIDP (n = 30) according to the Brighton and European Federation of Neurological Societies/Peripheral Nerve Society criteria by a physician blinded to biological results. Results CSF IL-8 was higher in GBS (median: 83.9 pg/mL) than in CIDP (41.0 pg/mL) (p < 0.001). Receiver operating characteristic analyses indicated that the optimal IL-8 cutoff was 70 pg/mL. Above this value, patients were more likely to present GBS than CIDP (specificity 96.7%, sensitivity 64.4%, positive predictive value [PPV] 96.7%, and negative predictive value [NPV] 64.4%). Among GBS subcategories, IL-8 was higher in acute inflammatory demyelinating polyneuropathy (AIDP, median: 101.8 pg/mL) than in other GBS variants (median: 53.7 pg/mL). In addition, with CSF IL-8 above 70 pg/mL, patients were more likely to present AIDP than acute-onset CIDP (p < 0.001; specificity 100%, sensitivity 78.8%, PPV 100%, and NPV 46.2%) or other CIDP with nonacute presentation (p < 0.0001; specificity 95.8%, sensitivity 78.8%, PPV 96.3%, and NPV 76.7%). Conclusion CSF IL-8 levels can help to differentiate AIDP variant of GBS from CIDP, including acute-onset CIDP, with high specificity and PPV. This may improve early and appropriate treatment. Classification of Evidence This study provides Class II evidence that CSF IL-8 levels accurately distinguish patients with GBS from those with CIDP.