ELISA方法进行婴幼儿HBsAg弱阳性标本检测的方法学评估

Detection of HBs Ag Weakly Positive Specimens in Infants with ELISA

目的评价ELISA方法在检测婴幼儿HBs Ag时的适用性。方法用弱阳性混合血清评价ELISA方法测定HBs Ag时的精密度;使用经化学发光法定值的混合血清系列稀释,分析ELISA方法测定HBs Ag时的检出限;使用添加350μmol/L胆红素或5g/L血红蛋白的系列浓度血清评价该方法的抗干扰能力;收集临床1岁以下患儿化学发光方法检测弱阳性(<5ng/m L)的样品,进行化学发光和ELISA方法的比对,并以化学发光确证试验为参考方法评价ELISA方法的诊断灵敏度、特异性和诊断效能。结果在弱阳性水平上(1ng/m L,S/CO=4.97)ELISA方法测定HBs Ag的变异系数为18.91%;检出限为0.125ng/m L;350μmol/L胆红素或5g/L血红蛋白对检验结果准确度无显著影响;经比对,ELISA法与化学发光法在小于0.25ng/m L区间一致率为30.3%,而在大于0.25ng/m L区间一致率达95.6%;以二者一致和化学发光法中和试验为参考方法,ELISA方法的灵敏度为87.14%,阴性预测值为79.07%。结论 ELISA方法尽管分析灵敏度低于化学发光法,然而它在测定婴幼儿弱阳性标本时,分析性能尚可接受,考虑到其方法的易得和低廉的成本,ELISA方法仍不失为一种好的筛查方法。

Objective To explore the applicability of ELISA for HBsAg detection in infants. Methods The HBsAg weakly positive pooled serums were used to evaluate the precision of ELISA. The serial dilutions of pooled serum were detected and valued by CMIA to analysis the LOD of ELISA in measuring HBsAg. The 350μmol/L bilirubin or 5g/L hemoglobin were added into serum to perform interference test. The serum samples from infant （ 〈 1 year） that were HBsAg positive tested with CMIA were detected with ELISA to evaluate the diagnostic sensitivity, specificity of ELISA. Results As to 1 ng/mL HBsAg weakly positive level sample, the coefficient of variation of ELISA was 18.91% and the LOD was 0. 125 ng/mL. The addition of 350μmol/L bilirubin or 5g/L hemoglobin had no significant effect on the accuracy of test results. As to less than 0.25 ng/mL HBsAg weakly positive level sample, the consistency of detection results by ELISA and CMIA was 30.3% , whereas on the level above 0.5 ng,/mL, the consistency reached 95.6%. The diagnostic sensitivity of ELISA was 87.14% , and the negative predictive value was 79.07%. Conclusion Despite the sensitivity of the ELISA method is worse than that of CMIA, however, on weakly positive level, the analytical performance of ELISA still acceptable. ELISA is a good screening method.