Abstract: Backgroup　Platelet-to-lymphocyte ratio（PLR） which was described as a new inflammatory marker could be used to predict the severity of community-acquired pneumonia（CAP） in patients.At present，there were few reports about this research in China.Objective　To investigate the clinical value of PLR in predicting the severity of CAP.Methods　According to the inclusion criteria of this study，we retrospectively selected 142 patients with CAP who hospitalized in the Second Affiliated Hospital of Zhengzhou University from January 2013 to March 2018.We collected their Clinical Pulmonary Infection Score（CPIS），and assigned 71 cases with CPIS≤6，71 cases with CPIS>6 to mild group and severe group，respectively.We obtained and compared the clinical data of both groups，including PLR，white blood cell count（WBC），neutrophil-lymphocyte ratio（NLR），C-reactive protein（CRP），procalcitonin（PCT），interleukin 6（IL-6）．Spearman correlation analysis was performed to investigate the correlation of PLR with WBC，NLR，CRP，PCT，IL-6 and CPIS.And the mortality rates within 28 days of being in hospital in both groups were analyzed to evaluate the predictive value of PLR for the prognosis of CAP.Results　The levels of PLR，WBC，NLR，CRP，PCT，and IL-6 in the severe group were higher than those in the mild group（P<0.05）．Spearman rank correlation analysis showed that PLR had no obvious correlation with WBC（rs=0.085，P=0.313），but was positively associated with NLR，CRP，PCT，IL-6 and CPIS（rs=0.488，0.415，0.489，0.490，0.491，P<0.001）．Within 28 days after admission，there were no deaths in the mild group but 5 deaths in the severe group.For predicting the mortality rate within 28 days following admission，the area under the ROC curve was 0.816〔95%CI（0.564，1.000）〕 for PLR，0.843〔95%CI（0.686，1.000）〕 for NLR，0.819〔95%CI（0.730，0.908）〕for CRP，0.781〔95%CI（0.578，0.984）〕 for PCT，0.793〔95%CI（0.708，0.877）〕 for IL-6，and 0.924〔95%CI（0.853，0.994）〕 for CPIS（P<0.05）.Conclusion　PLR is positively correlated with some indicators of inflammation.In other words，it can be used to evaluate the severity of CAP patients.And its predictive value for the prognosis of such patients proves to be valuable.

Key words: Pneumonia, Blood platelets, Lymphocytes, Forecasting

摘要： 背景　血小板与淋巴细胞比值（PLR）被描述为一种新的炎性标志物，可用来预测社区获得性肺炎（CAP）患者的严重程度，目前国内关于该项研究鲜有报道。目的　探究PLR预测CAP严重程度的临床价值。方法　回顾性选取2013年1月—2018年3月于郑州大学第二附属医院住院治疗符合纳入标准的CAP患者142例。依据患者临床肺部感染评分（CPIS）将其分为CPIS≤6分患者（轻症组，n=71）和CPIS>6分患者（重症组，n=71）。收集患者的临床资料，包括PLR、白细胞计数（WBC）、中性粒细胞与淋巴细胞比值（NLR）、C反应蛋白（CRP）、降钙素原（PCT）、白介素6（IL-6）。比较两组患者PLR、WBC、NLR、CRP、PCT、IL-6，采用Spearman秩相关分析分析患者PLR与WBC、NLR、PCT、IL-6及CPIS的相关性；观察两组患者入院后28 d内死亡情况，分析PLR预测CAP患者28 d内死亡的价值。结果　重症组患者PLR、WBC、NLR、CRP、PCT、IL-6高于轻症组（P<0.05）。Spearman秩相关分析结果显示，PLR与WBC无相关性（rs=0.085，P=0.313）；PLR与NLR、CRP、PCT、IL-6及CPIS呈正相关（rs分别为0.488、0.415、0.489、0.490、0.491，P<0.001）。入院28 d内，轻症组无死亡患者，重症组死亡5例。PLR、NLR、CRP、PCT、IL-6及CPIS预测CAP患者28 d内死亡的ROC曲线下面积为0.816〔95%CI（0.564，1.000）〕、0.843〔95%CI（0.686，1.000）〕、0.819〔95%CI（0.730，0.908）〕、0.781〔95%CI（0.578，0.984）〕、0.793〔95%CI（0.708，0.877）〕及0.924〔95%CI（0.853，0.994）〕（P<0.05）。结论　PLR与部分炎性反应程度相关指标呈正相关，可用来评估CAP患者的严重程度，且对患者的预后有较好的预测价值。

关键词: 肺炎, 血小板, 淋巴细胞, 预测