Introduction: Aspiration pneumonia is a common complication in the acute phase after ischemic stroke. Inflammation is associated with the initiation and progression of pneumonia after stroke. The neutrophil-to-lymphocyte ratio (NLR) has recently been described as a predictor of clinical outcomes in stroke. However, impact of NLR on the aspiration pneumonia in patients with ischemic stroke remains unclear.
Hypothesis: Therefore, we investigated that NLR on admission was related to the risk of aspiration pneumonia after ischemic stroke.
Methods: A consecutive 1,200 patients who were admitted within 7 days after ischemic stroke onset between March 2010 and March 2015 were included for analysis. The NLR was calculated as the ratio of neutrophils to lymphocytes. The patients were categorized into tertile groups based on the NLR. We evaluated aspiration pneumonia complication during hospitalization. We compared the clinical characteristics and NLR according to the presence of aspiration pneumonia.
Results: Among the included patients (mean age, 67.7 years; men, 59.7%), 97 (8.1%) patients experienced aspiration pneumonia during hospitalization following ischemic stroke. The patients with aspiration pneumonia were older and more likely to have atrial fibrillation, and diabetes mellitus. In addition, patients with aspiration pneumonia tended to have lower body mass index and higher initial NIHSS. The proportion of the NLR tertile 3 were significantly higher in the aspiration pneumonia group (30.7% vs. 64.9%, P < 0.001). Moreover, higher NLR patients were more likely to be admitted to the intensive care unit (1.0% vs. 1.3% vs. 5.0%, P < 0.001), and were more likely to have sepsis (defined by quick Sepsis-related Organ Failure Assessment score of ≥ 2; 0.5% vs. 1.8% vs. 4.2%, P = 0.001) After adjustment for covariates, the highest NLR tertile groups had an exaggerated risk for aspiration pneumonia [Odds ratio (95% confidence interval); tertile 3, 2.39 (1.20 – 4.77), P = 0.014].
Conclusions: This study demonstrated that higher NLR predicted aspiration pneumonia and severe infection following acute ischemic stroke. This suggests that NLR could be a useful and reliable prognostic biomarker for severe aspiration pneumonia after ischemic stroke.