实时PCR在侵袭性曲霉病中的诊断价值

摘要

目的 探讨实时(Real-time) PCR在侵袭性曲霉病(IA)高危患者中的诊断价值,与血清半乳甘露聚糖(GM)试验比较诊断性能.方法 回顾性调查分析2008年5月至2010年12月临床疑患IA住院患者110例次,根据诊断标准将确诊IA和临床诊断IA归为感染组,共23例次,拟诊IA和非IA归为非感染组,共87例次.对其住院期间的257份血清进行Real-time PCR和GM检测,绘制Real-time PCR的受试者操作曲线(ROC),计算ROC曲线下面积,制定最佳临界值；计算单次PCR阳性在不同分级诊断中的阳性率；计算不同PCR和(或)GM诊断条件下的灵敏度(Se)、特异度(Sp)、阳性预测值(PPV)和阴性预测值(NPV)等.采用McNemar配对x2检验对不同方法进行比较.结果 ROC曲线下面积为0.91 (95％ CI:0.825 ～0.995),最佳临界循环值为39.45.单次PCR阳性对确诊和临床诊断的诊断率分别为100％和84.2％.以单次PCR阳性、两次PCR阳性、单次GM阳性和两次GM阳性为诊断标准的Se和Sp分别为87.0％、79.3％,58.3％、97.8％,78.3％、63.2％和58.3％、82.6％.以单次、两次PCR阳性为诊断标准的Sp分别较单次、两次GM阳性显著升高(P＜0.05),而Se无统计学差异；两次PCR阳性与单次PCR阳性相比Sp显著升高(P＜0.05).1次GM阳性且1次PCR阳性的Se、Sp为65.2％、89.7％；1次GM阳性或1次PCR阳性Se达100％,Sp为52.3％.结论 Real-time PCR对侵袭性曲霉病具有较高的诊断价值,其灵敏度和特异度均优于GM试验；两次PCR阳诊断侵袭性曲霉病能够提高诊断的特异度和阳性预测值.%Objective To investigate the value of Real-time PCR in the diagnosis of invasive aspergillosis(IA) and to compare it with galactomannan antigen assays.Methods A retrospective study was performed on 110 episodes of hospitalization of 88 patients who were at risk of invasive aspergillosis at Peking University First and Renmin Hospital from May 2008 to December 2010.23 cases with diagnosis and clinical diagnosis IA were classified as infection group and 87 cases with suspected diagnosis and non-IA were classified as non-infeciton group according to the international criterion.Real-time PCR and gaiactomannan antigen detections were performed on 257 serum samples.A receiver operating characteristic curve (ROC)was developed based on the quantitative cycle numbers and an optimal cut off value of quantification cycle (Cq) was determined.The sensitivity (Se),specificity (Sp),positive predictive value (PPV) and negative predictive value (NPV) were calculated under different considerations among which McNemar chi-square tests were used for statistical analyze.Results The area under ROC curve of Real-time PCR for the diagnosis of IA was 0.91 (95％ CI:0.825-0.995) and the optimal cut off value of Cq was 39.45.The Se and Sp of one positive PCR,two positive PCR,one positive GM and two positive GM were 87.0％,79.3％ ; 58.3％,97.8％ ; 78.3％,63.2％ ; and 58.3％,82.6％,respectively.When one positive PCR was considered as the diagnostic criterion of IA,Real-time PCR was able to diagnose 100％ and 84.2％ of proven and probable IA cases,respectively.The Sp of one/two positive PCR were statistically higher than one/two positive GM (P ＜ 0.05),respectively.The Sp of two positive PCR was statistically higher than one positive PCR (P ＜0.05).The Se and Sp were 65.2％,89.7％ and 100％,52.3％ for one positive PCR combined one positive GM and one PCR or GM positive,respectively.Conclusions Real-time PCR assays have better sensitivities and specificities than GM in the diagnosis of invasive aspergillosis.When two PCR positive were considered,better specificity and positive predictive value were achieved.