High Neutrophil-to-Lymphocyte Ratio Predicts Stroke-Associated Pneumonia

Background and Purpose- Although there are a variety of risk factors and predictive models for stroke-associated pneumonia (SAP), more objective and easily accessible markers are still needed. In this study, we evaluated the relationship between the neutrophil-to-lymphocyte ratio (NLR) and SAP in patients with acute ischemic stroke. Methods- We assessed 1317 consecutive patients with acute ischemic stroke. SAP was defined according to the modified Centers for Disease Control and Prevention criteria. The severity of pneumonia was rated using scores from the Pneumonia Severity Index, the quick Sequential Organ Failure Assessment, and the Acute Physiology and Chronic Health Evaluation II. The NLR was calculated after dividing absolute neutrophil counts by absolute lymphocyte counts. Results- Among the total patients, SAP occurred in 112 (9.0%) patients. Using a multivariable analysis, the NLR (adjusted odds ratio=1.55; 95% confidence interval, 1.15-2.11; P=0.005) remained significant after adjusting for confounders. In addition, age, atrial fibrillation, previous stroke history, initial National Institutes of Health Stroke Scale score, and high-sensitivity C-reactive protein were also significant, independent of NLR. The NLR was higher in the severe pneumonia group when it was assessed by Pneumonia Severity Index ( P<0.001), quick Sequential Organ Failure Assessment ( P<0.001), and Acute Physiology and Chronic Health Evaluation II scores ( P=0.004). Furthermore, patients who had SAP had worse clinical outcomes both during hospitalization and after discharge. Conclusions- We demonstrated that a higher NLR predicted SAP in patients with acute ischemic stroke. The NLR may help to identify high-risk patients in time and provide clues for further studies about preventive antibiotic therapy.