Increased Neutrophil-to-lymphocyte Ratios are Associated with Greater Risk of Hemorrhagic Transformation in Patients with Acute Ischemic Stroke

Background and Purpose: Leukocyte is currently known as a potential risk factor for symptomatic intracranial hemorrhage after reperfusion therapy, but there is little evidence on whether leukocyte is associated with the overall risk of Hemorrhagic Transformation (HT) after Acute Ischemic Stroke (AIS). Methods: Patients within seven days after stroke onset were included between January 2016 and October 2017. The laboratory data were collected within 24 hours after admission. HT was defined as hemorrhage presented on follow-up magnetic resonance imaging or Computed Tomography (CT) but not on baseline CT. The univariate analysis and multivariate logistic regression were performed to assess the association of white blood cell, neutrophil, lymphocyte, Neutrophil-To-Lymphocyte Ratio (NLR) with HT. Then the relationship between their levels and HT in different stroke subtypes was further studied. Results: We included 1233 Chinese AIS patients (mean age 64.10 +/- 14.53 years; 63.5% male). HT occurred in 145 patients (11.8%). After adjusting for confounders, NLR (odds ratio [OR] 1.295, 95% Confidence Interval [CI] 1.085-1.546, P=0.004) was independently associated with HT. In stroke subtypes, NLR was found to be significantly related to HT in cardio-embolic stroke (OR 1.366, 95% CI 1.019-1.830, P=0.037) but showed no significance in large-artery atherosclerosis, small-artery occlusion and undetermined etiology. Conclusions: Higher level of NLR is associated with greater risk of hemorrhagic transformation in patients with acute ischemic stroke, especially in cardio-embolic stroke. Moreover, the results suggest that therapeutic interventions that may increase the risk of bleeding should be undertaken carefully in the management of AIS patients with higher NLR.