献血者HBsAg及抗-HCV ELISA筛查不合格标本的假阳性分析

Evaluation on the false positive rate of unqualified donors with positive HBsAg and anti-HCV ELISA screen test

目的了解献血者乙型肝炎表面抗原(HBsAg)及抗-丙型肝炎病毒(HCV)ELISA筛查不合格标本的假阳性情况。方法对2009年2～5月常规国产和进口双试剂ELISA筛查HBsAg不合格的107份标本采用核酸和血清学中和试验加以确认,对常规国产和进口双试剂ELISA筛查抗-HCV不合格的184份标本采用核酸和血清学RIBA试验加以确认。核酸和(或)血清学补充试验阳性判为确认阳性,不能被确认阳性者判为假阳性。对假阳性情况进行统计分析。结果 HBsAg筛查不合格标本中,HBsAg ELISA双试剂阳性、单试剂阳性、灰区标本的假阳性率分别为2.0%、58.7%、63.6%,总假阳性率为32.7%;抗-HCV筛查不合格标本中,抗-HCVELISA试剂假阳性率分别为23.9%、95.2%、96.1%,总假阳性率为67.9%。HBsAg国产试剂单阳及灰区的假阳性率[78.6%(11/14),100%(3/3)]高于进口试剂单阳及灰区的假阳性率[50.0%(16/32),50.0%(4/8);χ2=5.188,P<0.05];抗-HCV国产试剂单阳及灰区的假阳性率[96.3%(26/27),95.5%(21/22)]与进口试剂单阳及灰区的假阳性率[94.3%(33/35),93.5%(29/31)]差别不大(χ2=1.048,P>0.05)。结论灰区标本的假阳性率极高,但从血液安全考虑灰区设置有必要;抗-HCVELISA检测的假阳性问题较HBsAgELISA严重;针对血液筛查假阳性问题,建议对血液及献血者应独立管理,建立献血者归队方案。目前HBsAg进口试剂的特异性优于国产试剂,而抗-HCV试剂的特异性进口试剂与国产试剂差别不大。

Objective To evaluate the false positive rate of unqualified donors with positive HBsAg and anti-HCV ELISA screen test. Methods One hundred and seven samples with positive HBsAg ELISA results from routine donor screening using a domestic kit and an imported kit were confirmed by nucleic acid test （NAT） and serological supplemental neutralization test; 184 samples with unqualified anti-HCV ELISA results from routine donor screening using a domestic kit and an imported kit were confirmed by NAT and serological supplemental RIBA test. Samples with NAT positive and/or serological supplemental test positive were considered as definite positive. Samples which could not be confirmed by NAT and/or serological supplemental test were considered as false positive. The false positive rates were statistically analyzed. Results Among the positive HBsAg screening samples, the false positive rates of samples which were positive by both HBV ELISA kits, single kit, and grey area were 2.0%, 58.7% and 63.6%, respectively. The total false positive rate was 32.7%. Among anti-HCV screening unqualified samples, the false positive rates of samples which were positive by both anti-HCV ELISA kits, single kit, and grey area were 23.9%, 95.2% and 96.1%, respectively. The total false positive rate was 67.9%. The false positive rate of domestic HBsAg kit with single positive or grey area result [78.6% （11/14）, 100% （3/3）] was higher than that of the imported klBsAg kit＇s [50.0% （16/32）, 513.0% （4/8）; %2=5.188, P 〈 0.05]. There was no significant difference in the false positive rate of domestic anti-HCV kit with single positive or grey area result [96.3% （26/27）, 95.5% （21/22）] between the imported and domestic anti-HCV kit＇s [94.3% （33/35）, 93.5% （29/31）; χ2=1.048, P 〉0.05]. Conclusion Samples with grey area result have a quite high false positive rate, however, setting up the grey area seem to be necessary when transfusion safety is considered. The false positive rate of anti-HCV ELISA screening was more serious than that of HBsAg screening test. For the false positive in donors screening, we suggest that these samples should be managed seperately, and an appropriate blood donor rejoin program should be established. The specificity of the current imported HBsAg kit is better than that of the domestic HBsAg kit, while there is no significant difference in the specificity of the current anti-HCV kits between the imported and the domestic anti-HCV kit.