Neutrophil to lymphocyte ratio and adverse clinical outcomes in patients with ischemic stroke

Background: Neutrophils and lymphocytes mediate differential inflammatory responses after ischemic stroke and have different effects on patients' clinical outcomes. Several studies have used the neutrophil to lymphocyte ratio (NLR) as a prognostic indicator for ischemic stroke; however, some limitations remain. Methods: We derived data from the Third China National Stroke Registry. The NLR is defined as neutrophil count/lymphocyte count. Patients included in the study were classified into four groups by NLR quartiles. Odds ratios (ORs) of adverse clinical outcomes were calculated with the lowest quartile group as the reference category. We plotted receiver operating characteristic (ROC) curves of NLR for adverse clinical outcomes and calculated area under the curve (AUC) values and cutoff values. Under different TOAST classifications, medians of NLR and ORs of adverse clinical outcomes were also calculated. Furthermore, interaction tests between NLR and etiology were performed. Results: A total of 13,018 patients were enrolled. At both 3- and 12-month follow-ups, higher quartile groups were associated with increased risks of death and poor functional outcomes, even after adjustments. For death, the cutoff values of NLR were 3.872 at 3-month follow-up and 3.180 at 12-month follow-up. For poor functional outcomes, the cutoff value of NLR was 2.846 at both 3- and 12-month follow-ups. The association between NLR and stroke recurrence was significant only at 3-month follow-up before adjustments. There was no correlation between NLR and hemorrhagic transformation during hospitalization. Under different TOAST classifications, the medians of NLR were different; conversely, the correlations of NLR with adverse clinical outcomes had no differences. Conclusions: High level of NLR within the first 24 h after admission was associated with increased risks of both short- and long-term adverse clinical outcomes in patients with ischemic stroke, regardless of etiology.