目的 评估全身免疫炎症指数(systemic immune-inflammation index，SII)对血液透析患者导管相关血流感染(catheter-related bloodstream infection，CRBSI)的诊断价值。 方法  回顾性分析196例维持性血液透析(maintenance hemodialysis，MHD)患者的临床资料。根据导管类型将患者分为隧道式中心静脉导管(tunneled central catheter，TCC)组和非隧道式中心静脉导管(non-tunneled central catheter，NCC)组，各组内进一步分为感染亚组与对照亚组。收集患者临床资料并计算SII。采用受试者工作特征(receiver operating characteristic，ROC)曲线评估SII对CRBSI的诊断效能；分析感染患者抗感染治疗前后SII的变化；比较革兰氏阳性(gram-positive，G+)与革兰氏阴性(gram-negative，G-)菌感染者炎症指标差异；评估SII、C反应蛋白(C-reactive protein，CRP)等指标对病原菌类型的鉴别诊断效能。 结果  TCC组共纳入90例患者(感染亚组28例，对照亚组62例)，NCC组共纳入106例患者(感染亚组27例，对照亚组79例)。TCC组与NCC组中，感染亚组患者的SII水平均高于对应的对照亚组(TCC组：Z =-5.429，P＜0.001；NCC组：Z=-5.850，P＜0.001)。抗感染治疗后，感染患者SII下降(t=6.173，P＜0.001)。ROC曲线显示：TCC组中，SII诊断CRBSI的曲线下面积(area under the curve，AUC)为0.859(敏感度82.2%，特异性78.5%)；NCC组中，AUC为0.878(敏感度85.1%，特异性77.2%)。G-菌感染者CRP水平高于G+菌感染者(Z=-4.236，P＜0.001)；在鉴别G+与G-菌感染时，CRP的AUC(0.875)高于中性粒细胞(AUC=0.699，Z=6.442，P＜0.001)、淋巴细胞(AUC=0.671，Z=4.531，P＜0.001)、SII(AUC=0.553，Z=3.818,P＜0.001)等其他炎症指标。 结论 全身免疫炎症指数与C反应蛋白在CRBSI的早期诊断中具有重要临床价值。

Objective This study aimed to assess the diagnostic utility of systemic immune-inflammation index (SII) for catheter-related bloodstream infection (CRBSI) among patients undergoing maintenance hemodialysis (MHD).  Methods  A retrospective analysis was conducted on the clinical data of 196 MHD patients. Participants were categorized into a tunneled central catheter (TCC) group (n=90) and a non-tunneled central catheter (NCC) group (n=106). Each group was subdivided into an infection subgroup and a control subgroup. SII was calculated from the collected clinical parameters. Receiver operating characteristic (ROC) curve analysis was employed to evaluate the diagnostic performance of SII for CRBSI. Changes of SII level before and after anti-infective treatment in infected patients were analyzed. In addition, differences in inflammatory markers between Gram-positive (G+) and Gram-negative (G-) bacterial infections were compared. The discriminative ability of SII, C-reactive protein (CRP), and other biomarkers for pathogen type was also assessed.  Results  The 90 patients in TCC group included 28 in infection subgroup and 62 in control subgroup; the 106 patients in NCC group were comprised of 27 in infection subgroup and 79 in control subgroup. SII level was significantly higher in the infection subgroups than in the control subgroups, including comparison of the subgroups in TCC group (Z=-5.429, P<0.001) and that of the subgroup in NCC group (Z=-5.850, P<0.001). Anti-infection therapy achieved a significant reduction of SII among infection patients (t=6.173, P<0.001). ROC analysis indicated that the area under the curve (AUC)  of SII for the diagnosis of CRBSI was 0.859 with the sensitivity of 82.2% and the specificity of 78.5% in TCC group, while the AUC of SII for the diagnosis of CRBSI was 0.878 with the sensitivity of 85.1% and the specificity of 77.2% in NCC group. CRP level was significantly higher in patients with G- infections than in those with G+ bacterial infections (Z=-4.236, P<0.001). For discriminating between G+ and G- infections, the AUC of CRP (AUC=0.875) was higher than the AUCs of neutrophils (AUC=0.699, Z=6.442, P<0.01), lymphocytes (AUC=0.671, Z=4.531, P<0.001), and SII (AUC=0.553, Z=3.818, P<0.001).  Conclusion  SII and C-reactive protein are important clinical indicators for the early diagnosis of CRBSI.