Increased Neutrophil-to-Lymphocyte Ratio is Associated with Unfavorable Functional Outcome in Acute Ischemic Stroke

Background Inflammatory response is the hallmark of secondary brain injury in stroke patients. Neutrophil-to-lymphocyte ratio (NLR) emerged as a marker for functional outcome in several diseases. Objectives To investigate the association between NLR on admission and during hospital stay and functional outcome in acute ischemic stroke (AIS). Methods This observational study included all consecutive AIS patients admitted at a German stroke center covering 2011-2013. Patient characteristics and clinical data were retrieved from institutional databases. Multivariate analysis was conducted to investigate parameters associated with functional outcome. Receiver operating characteristic (ROC) analysis was performed to identify the best cutoff for NLR to discriminate between favorable and unfavorable functional outcome. To account for imbalances in baseline characteristics, propensity score matching was carried out to assess the influence of NLR on functional outcome. Results A total of 807 patients with AIS were included for analysis. Patients with worse functional outcome at 3 months were older and had worse clinical status on admission, higher rates of infectious complications, and an increased NLR. ROC analysis identified a NLR of 3.3 as best cutoff value to discriminate between favorable and unfavorable functional outcomes (area under the curve 0.693, p < 0.001, Youden's index = 0.318; p < 0.001; sensitivity 68.5%, specificity 63.9%). Propensity-matched analysis still demonstrated a higher rate of unfavorable functional outcome at 3 months in patients with NLR >= 3.3 [modified Rankin scale 3-6 at 3 months: NLR >= 3.3 51.5% vs. NLR < 3.3 36.4%; p = 0.002]. Conclusions In AIS patients we identified NLR as an important predictor for unfavorable functional outcome.