评价血小板相关抗体定量测定法对特发性血小板减少性紫癜的诊断价值

目的 :评价血小板相关抗体 (PAIg)定量测定法对诊断特发性血小板减少性紫癜 (ITP)的价值。 方法 :应用酶联免疫竞争抑制试验 (ELISA)定量测定血小板相关抗体 ,计算试验的灵敏度、特异度、准确度、阳性预测值 ,绘制受试者ROC曲线进行诊断价值的评价。结果 :根据常用判断PAIg阳性的临界值 ,血小板相关抗体试验诊断ITP的灵敏度较高 (95 % ) ,但特异度低 (48.8% ) ,准确度低 (5 7.5 % ) ,阳性预测值低 (30 .2 % )。用ROC曲线寻找诊断ITP的最佳临界值 ,用新的临界值 (PAIgG >16 0ng/10 7血小板或PAIgA >2 5ng/10 7或PAIgM >35ng/10 7)时 ,可提高诊断试验的特异度 ,从 4 8.8%提高到 6 2 .8% ,可确诊更多的患者 ;但准确度和阳性预测值仍低 ,分别为 6 7.9%和 36 .0 %。结论 :PAIg试验诊断ITP的特异度、准确度、阳性预测值较低 ,帮助诊断ITP的临床价值有限 ,即使用新的临界值提高了试验的特异度 ,但诊断ITP的价值仍不大。

The evaluation of diagnostic value of platelet-associated immunoglobulin for idiopathic thrombocytopenic purpura

Objective:To evaluate the diagnosis value of the platelet associated immunoglobulin(PAIg) for idiopathic thrombocytopenic purpura(ITP).Method:The platelef associ ated immunoglobulin was detected by ELISA.Sensitivity, specificity, validity, positive predictive value, receiver operator characteristic(ROC) curve were used to assess the diagnostic Value of PAIg.Result:According to the old cut off points, the sensitivity of PAIg diagnostic test was 95%, the specificity 48.8 %, the validity 57.5 %, positive predictive value 30.2 %. According to the new cut off points coming from ROC curve, the specificity was 62.8 %, the validity 67.9 %, the positive predictive value 36%.Conclusion:The specificity, validity and positive predictive value of the test were lower to diagnose ITP. The diagnostic value was limited to ITP diagnosis.