功能性血小板活化试验,如5-羟色胺释放测定(SRA),是诊断肝素诱导的血小板减少症(HIT)的金标准。最近,已经描述了使用添加血小板因子4(PF4)的血小板活化测定,并提出了改善的敏感性.尚未进行这些测定的直接比较。
我们比较了三种PF4增强血小板活化试验的性能特征,PF4/肝素-SRA(PF4/HEP-SRA),PF4-SRA,和P-选择素表达测定(PEA),在一个单一的参考实验室。
使用来自两组患者的血清样品。转诊队列(n=84)包括先前已接受HIT常规诊断测试并使用SRA测试为阳性或阴性的样品。临床队列(n=101)由来自具有临床证实的HIT的患者的样品组成,所述患者的血清含有血小板活化抗体。我们同时在PF4增强的基于SRA的测定中测试了所有样品(PF4/hep-SRA,PF4-SRA)和基于流式细胞术的PEA。
在转诊队列中,3个PF4增强试验鉴定出先前在SRA中被确定为阳性的所有样品.然而,PF4/hep-SRA的特异性为96.6%,PF4-SRA为84.7%,PEA为67.8%。在样本的临床队列中,所有基于SRA的检测均表现出高性能特征(>92.1%的灵敏度,>98.4%特异性)。PEA的敏感性和特异性最低,65.8%和63.5%,分别;但使用预选的血小板供体提高到92.1%和96.8%。
当血小板供体被预选时,所有PF4增强的测定显示出良好的性能特征。应在多个实验室之间进行进一步比较,以就最佳HIT诊断测试达成共识。
Functional platelet activation assays, such as the serotonin release assay (SRA), are the gold standard for the diagnosis of heparin-induced thrombocytopenia (HIT). Recently, platelet activation assays using added platelet factor 4 (PF4) have been described and suggest improved sensitivity. Direct comparisons of these assays have not been performed.
We compare the performance characteristics of three PF4-enhanced platelet activation assays, the PF4/heparin-SRA (PF4/hep-SRA), the PF4-SRA, and the P-selectin expression assay (PEA), at a single reference laboratory.
Serum samples from two cohorts of patients were used. The referral cohort (n = 84) included samples that had previously undergone routine diagnostic testing for HIT and tested positive or negative using the SRA. The clinical cohort (n = 101) consisted of samples from patients with clinically confirmed HIT whose serum contained platelet-activating antibodies. We simultaneously tested all samples in PF4-enhanced SRA-based assays (PF4/hep-SRA, PF4-SRA) and the flow cytometry-based PEA.
In the referral cohort, the three PF4-enhanced assays identified all samples that were previously determined to be positive in the SRA. However, specificity of the PF4/hep-SRA was 96.6%, the PF4-SRA was 84.7%, and the PEA was 67.8%. In the clinical cohort of samples, all SRA-based assays displayed high performance characteristics (>92.1% sensitivity, >98.4% specificity). Sensitivity and specificity of the PEA was the lowest, 65.8% and 63.5%, respectively; but improved to 92.1% and 96.8% using preselected platelet donors.
All PF4-enhanced assays demonstrated good performance characteristics when platelet donors were preselected. Further comparisons across multiple laboratories should be conducted for consensus on optimal HIT diagnostic testing.