Lowsby Richard, Gomes Clint, Jarman Ian, Lisboa Paulo, Nee Patrick A, Vardhan Madhur, Eckersley Tom, Saleh Roshan, Mills Hannah
Departments of Emergency and Critical Care Medicine, St. Helens and Knowsley Hospitals NHS Trust, Whiston Hospital, Merseyside, UK.
Liverpool John Moores University, Liverpool, UK.
Emerg Med J. 2015 Jul;32(7):531-4. doi: 10.1136/emermed-2014-204071. Epub 2014 Sep 2.
Early identification of patients with blood stream infection (BSI), especially bacteraemia, is important as prompt treatment improves outcome. The initial stages of severe infection may be characterised by increased numbers of neutrophils in the peripheral blood and depression of the lymphocyte count (LC). The neutrophil to LC ratio (NLCR) has previously been compared with conventional tests, such as C-reactive protein (CRP) and white cell count (WCC), and has been proposed as a useful marker in the timely diagnosis of bacteraemia.
Data on consecutive adult patients presenting to the emergency department with pyrexial illness during the study period, November 2009 to October 2010, were analysed. The main outcome measure was positive blood cultures (bacteraemia). Sensitivity, specificity, positive and negative predictive values and likelihood ratios were determined for NLCR, CRP, WCC, neutrophil count and LC.
1954 patients met the inclusion criteria. Blood cultures were positive in 270 patients, hence the prevalence of bacteraemia was 13.8%. With the exception of WCC, there were significant differences in the mean value for each marker between bacteraemic and non-bacteraemic patients (p<0.001). The area under the receiver operating characteristic curve was highest for NLCR (0.72; 95% CI 0.69 to 0.75) and LC (0.71; 0.68 to 0.74) and lowest for WCC (0.54; 0.40 to 0.57). The sensitivity and specificity of NLCR for predicting bacteraemia were 70% (64% to 75%) and 57% (55% to 60%), respectively. Positive and negative predictive values for NLCR were 0.20 (0.18 to 0.23) and 0.92 (0.91 to 0.94), respectively. The positive likelihood ratio was 1.63 (1.48 to 1.79) and the negative likelihood ratio was 0.53 (0.44 to 0.64).
Although NLCR outperforms conventional markers of infection, it is insufficient in itself to guide clinical management of patients with suspected BSI, and it offers no advantage over LC. However, it may offer some diagnostic utility when taken into account as part of the overall assessment.
早期识别血流感染（BSI）患者，尤其是菌血症患者非常重要，因为及时治疗可改善预后。严重感染的初始阶段可能表现为外周血中性粒细胞数量增加和淋巴细胞计数（LC）降低。此前已将中性粒细胞与淋巴细胞计数比值（NLCR）与传统检测指标，如C反应蛋白（CRP）和白细胞计数（WCC）进行比较，并提出NLCR可作为菌血症及时诊断的有用标志物。
分析了2009年11月至2010年10月研究期间因发热性疾病到急诊科就诊的成年连续患者的数据。主要观察指标为血培养阳性（菌血症）。确定了NLCR、CRP、WCC、中性粒细胞计数和LC的敏感性、特异性、阳性和阴性预测值以及似然比。
1954例患者符合纳入标准。270例患者血培养阳性，因此菌血症患病率为13.8%。除WCC外，菌血症患者和非菌血症患者各标志物的平均值存在显著差异（p<0.001）。NLCR（0.72；95%CI 0.69至0.75）和LC（0.71；0.68至0.74）的受试者工作特征曲线下面积最高，WCC（0.54；0.40至0.57）最低。NLCR预测菌血症的敏感性和特异性分别为70%（64%至75%）和57%（55%至60%）。NLCR的阳性和阴性预测值分别为0.20（0.18至0.23）和0.92（0.91至
