Supplementary Material for: High Neutrophil-to-Lymphocyte Ratio Predicts One-Year Risk of Pneumonia Post-Stroke Discharge

<b><i>Introduction:</i></b> 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. <b><i>Methods:</i></b> 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. <b><i>Results:</i></b> 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. <b><i>Conclusion:</i></b> 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.

<b><i>引言：</i></b> 中性粒细胞与淋巴细胞比值（neutrophil-to-lymphocyte ratio, NLR）可用于预测卒中相关性肺炎，后者通常定义为卒中发生后第一周内出现的肺炎。然而目前尚不清楚初始NLR是否与卒中幸存者长期随访期间的肺炎发病风险相关。本研究旨在明确急性卒中患者出院后1年内，入院NLR与卒中后肺炎发病风险之间的关联。<b><i>方法：</i></b> 检索医院数据库，筛选因急性卒中住院的成年患者。通过白细胞分类计数提取入院时的NLR。本研究的主要结局为卒中患者出院后1年内因肺炎住院的事件。采用多因素Cox比例风险模型分析NLR对肺炎发病风险的独立影响。<b><i>结果：</i></b> 本研究共纳入5741例急性卒中患者（平均年龄68岁；男性占比62.1%）。患者的NLR中位数为2.72（四分位间距1.78~4.49）。其中342例（6.0%）患者在出院后1年内发生肺炎。多因素模型分析显示，无论将NLR作为连续变量还是二分变量进行分析，其均为出院后肺炎发生的显著预测因子。对应的校正后风险比分别为1.037（95%置信区间[CI]：1.013~1.061）与1.361（95% CI：1.087~1.704）。<b><i>结论：</i></b> 入院NLR可预测急性卒中患者出院后长达1年的卒中后肺炎发病风险，有助于识别高危卒中幸存者，从而为其制定针对性干预措施。