目的：探讨血清降钙素原（procalcitonin,PCT）、白细胞介素6（interleukin 6,IL-6）以及C反应蛋白（reaction protein,CRP）在鉴别老年社区获得性肺炎（community acquired pneumonia,CAP）与上呼吸道感染中的辅助诊断价值。方法：选择本院2016年1月1日至2016年12月31日,于我院住院治疗的老年CAP患者103例作为研究组,50例上呼吸道感染而排除CAP的老年人作为对照组。研究组中,痰培养结果为阳性者45例,58例为痰培养呼吸道正常菌。所有研究对象分别检测血清PCT、IL-6、CRP,并对检测结果进行统计学分析,以PCT>0.25 ng/mL,IL-6>7 pg/mL,CRP>8 mg/L为阳性,分析3个指标鉴别老年CAP的灵敏度和特异度,同时以受试者工作特征曲线（receiver operating characteristic curve, ROC 曲线）评估PCT、IL-6及CRP在45例痰培养结果为阳性的细菌性老年CAP患者中诊断CAP的效能。结果：PCT、IL-6、CRP水平在对照组与研究组之间差异均有统计学意义(P<0.05),CRP诊断CAP的灵敏度为92.2%,高于PCT和IL-6, PCT的特异度为94.0%,明显高于CRP和IL-6,差异均具有统计学意义（P均<0.05）。PCT、IL-6、CRP联合检测（平行试验,即任意一项阳性）的灵敏度为96.1%,高于CRP的灵敏度92.2%,差异有统计学意义（P<0.05）,但联合检测的特异度略有下降,为68%。CAP患者血清PCT与CRP水平之间具有一定的相关性（r=0.524 7,P<0.001）。三个检测指标在诊断细菌性老年CAP的ROC曲线显示,PCT的ROC曲线下面积为0.773, CRP的曲线下面积为0.534,IL-6的曲线下面积为0.542。当PCT临界值取>0.21 ng/mL,其诊断细菌性老年CAP的灵敏度为84.4%,特异度为79.3%。结论：鉴别上呼吸道感染的老年患者与老年CAP患者时, PCT、IL-6以及CRP均可以作为老年CAP的辅助诊断检测指标,三者联合检测能提高诊断老年CAP患者的灵敏度,同时PCT在鉴别诊断细菌性老年CAP中的价值高于CRP和IL-6。

Objective: To investigate the auxiliary diagnostic value of serum procalcitonin (PCT), interleukin-6(IL-6) and C-reactive protein(CRP) for community acquired pneumonia (CAP) among elderly patients. Methods: A total of 103 elderly inpatients with CAP during January 1 to December 31, 2016 were enrolled in this study, and 50 cases of elderly patients with upper respiratory tract infection were served as controls. Sputum bacterial culture was positive in 45 of 103 CAP patients, and was negative in the other 58 patients. Levels of PCT, IL-6 and CRP were measured in all the patients. PCT>0.25 ng/mL, IL-6>7 pg/mL, CRP>8 mg/L were taken as cut-off value of positivity, and sensitivity and specificity for CAP were measured . Receiver operating characteristic (ROC) curve of the 45 cases with positive sputum bacterial culture was used to evaluate the diagnostic performance of PCT, IL-6 and CRP for CAP. Results: Serum levels of PCT, IL-6 and CRP were higher in CAP group than in control group (P<0.05). Sensitivity of CRP for diagnosing CAP (92.2%) was higher than those of IL-6 and PCT (P<0.05), and PCT had the highest specificity (94.0%) for the diagnosis of CAP(P<0.05). Meanwhile, the sensitivity of combined detection (parallel test: positive for any item) of these three biomarkers for the diagnosis of CAP were 96.1%, which was higher than the sensitivity of CRP-92.2% (P<0.05), however, the specificity of combined detection decreased slightly to 68%. In CAP patients, Pearson correlation coefficients revealed that PCT level was positively correlated with CRP level (r=0.528, P<0.001). Area under receiver operating characteristic(ROC) curve (AUC) for PCT, CRP and IL-6 were 0.773, 0.534, and 0.542, respectivlely; when PCT>0.21 ng/mL was taken as the cut-off value, the sensitivity and specificity for diagnosing CAP were 84.4% and 79.3%, respectively. Conclusions: PCT, IL-6 and CRP could be used as biomarkers in differentiating CAP from upper respiratory tract infection in elderly patients, and the combination of PCT, IL-6 and CRP might improve the diagnostic sensitivity for CAP. Meanwhile, PCT is more valuable than IL-6 and CRP for the auxiliary diagnosis of bacterial CAP.