关键词: 系统性红斑狼疮; 红细胞沉降率/C反应蛋白比值; 降钙素原; 细菌性感染

Abstract: Objective To evaluate the value of erythrocyte sedimentation rate(ESR)/C reactive protein(CRP) ratio combined with procalcitonin(PCT) in the differential diagnosis of systemic lupus erythematosus(SLE) activity and bacterial infection.Methods A total of 167 patients with SLE were divided into active group(SLE active patients,64 cases) and infection group(SLE patients with bacterial infection,103 cases).Levels of ESR,CRP,ESR/CRP ratio and PCT were compared between the two groups.Value of above indexes in differential diagnosis of SLE activity and bacterial infection was evaluated by receiver operating characteristic(ROC) curve.Results CRP and PCT in patients of active group were lower than those of infection group,while ESR and ESR/CRP ratio were higher than those of infection group(P<0.05).Sensitivity of PCT combined with ESR/CRP ratio in differential diagnosis of SLE activity and bacterial infection was higher than that of PCT,CRP,ESR/CRP ratio and PCT combined with CRP(P<0.05),while there were no significant differences among specificity of above 5 indexes（P>0.05）.Area under ROC curve(AUC) for differential diagnosis of SLE activity and bacterial infection by PCT combined with ESR/CRP ratio was higher than that of CRP,ESR,PCT,ESR/CRP ratio and PCT combined with CRP(P<0.05),and Youden index(YI) of CRP,ESR,PCT,ESR/CRP ratio was 0.36,0.23,0.40 and 0.54 respectively,whose corresponding values were 22.02mg/L,39mm/h,1.69ng/ml and 11.75 respectively.Conclusion Levels of PCT and CRP increase in SLE patients with bacterial infection.ESR/CRP ratio can be used as a new index to identify SLE activity and bacterial infection,and ESR/CRP ratio<11.75 indicates a high possibility of bacterial infection.PCT combined with ESR/CRP ratio can improve the differential diagnosis value of SLE activity and bacterial infection.

Key words: Systemic lupus erythematosus; Erythrocyte sedimentation rate/C-reactive protein ratio; Procalcitonin; Bacterial infection