High Neutrophil-to-Lymphocyte Ratio Predicts One-Year Risk of Pneumonia Post-Stroke Discharge

Abstract

Introduction: The neutrophil-to-lymphocyte ratio (NLR) may predict stroke-associated pneumonia, which is generally defined as pneumonia occurring in the first week after stroke. However, little is known whether the initial NLR is associated with pneumonia risk during the long-term follow-up in stroke survivors. We aimed to determine the relationship between admission NLR and the risk of post-stroke pneumonia within 1 year after discharge from acute stroke care. Methods: Hospital databases were searched to identify adult patients hospitalized for acute stroke. Admission NLR was extracted using differential leukocyte counts. The outcome of interest was hospitalized pneumonia occurring within 1 year after discharge from hospitalization for stroke. Multivariable Cox proportional-hazards models were used to determine the independent effects of the NLR on the risk of pneumonia. Results: In this study, 5,741 patients with acute stroke (mean age, 68 years; men, 62.1%) were analyzed. The median NLR was 2.72 (interquartile range, 1.78–4.49). Of the patients, 342 (6.0%) developed pneumonia within 1 year after discharge. In the multivariable models, the NLR was a significant predictor of pneumonia after discharge whether it was analyzed as a continuous or dichotomized variable. The corresponding adjusted hazard ratios were 1.037 (95% confidence interval [CI], 1.013–1.061) and 1.361 (95% CI, 1.087–1.704), respectively. Conclusion: The NLR could predict the risk of post-stroke pneumonia up to 1 year after discharge from acute stroke care. It may help identify high-risk stroke survivors, for whom appropriate interventions can be targeted.