无偿献血者乙肝表面抗原ELISA试剂筛查S/CO值与HBsAg阳性的相关性研究

目的了解献血者乙肝病毒表面抗原(HBsAg)初筛(试剂)反应性结果S/CO值与真阳性的相关性,为制定合理的HBsAg初筛反应性献血者归队策略提供依据。方法采用3种HBsAg酶联免疫吸附试验(ELISA)试剂(以国产试剂1、国产试剂2、进口试剂代称)和1种国产核酸检测(NAT)试剂对2017年7月-2017年9月在长春市献血的9 951(人)份献血者血标本做初筛试验,凡是反应性包括所有试剂(试验)反应性、单试剂反应性和灰区反应性(0.8≤S/CO﹤1.0)]血清标本再以中和试验(ELISA法)确证。使用SPSS 16.0统计学软件绘制HBsAg S/CO值与确证结果的接受者操作特性曲线(ROC),分析各S/CO值区间的阳性预测值,寻找灵敏度和特异性相适的S/CO值临界点。结果 1)献血者HBsAg初筛反应性率0.58%(58/9951),中和试验确证HBsAg阳性者比例20.69%(12/58)、阴性者比例79.31%(46/58)例;ELISA国产试剂1、2及进口试剂初筛与中和试验的阴性符合率均为100%,阳性符合率分别为57.14%(12/21)、66.67%(12/18)及27.27%(12/44)。2)ROC分析:国产试剂1、2及进口试剂HBsAg初筛试验相适的S/CO值临界点分别为1.635、3.605及3.245,敏感度为1、0.917及1,特异性为0.957、0.978及0.761。3)中和试验确证:12例HBV为阳性的献血者直接屏蔽(其中10例为NAT阳性),46例阴性献血者可继续追踪确定是否为感染状态(46例均NAT阴性)。结论每种ELISA试剂都有1个适宜的S/CO值,检测结果大于等于这个S/CO值时,其HBsAg真阳性率较高,可直接判为阳性,无需追踪确证。

The correlation between signal-to-cutoff ratios of HBsAg screening detection and confirm HBV infections

Objective To understand the correlation between the initial signal-to-cutoff(S/CO) ratios of HBsAg screening test and confirm HBV infections, thus to provide a theoretical basis for developing a blood donor reentry strategy for screening HBsAg reactive donors. Methods Between July 2017 to September 2017, three HBsAg enzyme-linked immunosorbent assay(ELISA) reagents(including domestic reagent 1, domestic reagent 2, and imported reagent) and one domestic nucleic acid testing(NAT) reagent were applied to detect 9951 blood donors′ samples in Changchun Blood Center. The serum samples of reactive donors(including all reagents reactivity, dual or single reagent reactivity and grey area reactivity, 0.8≤S/CO<1.0) were confirmed using Neutralization experiment. The receiver operating characteristic(ROC) curve of HBsAg S/CO ratio and confirmation result was plotted with SPSS 16.0 software;the positive predictive value and the critical value of S/CO ratio with the optimal sensitivity and specificity were analyzed. Results The main results were as follows:1) Among 58(58/9 951,0.58%) HBsAg initially screened reactive samples, 12 cases(12/58,20.69%) were positive for neutralization experiment, and 46 cases(46/58,79.31%) were negative for neutralization experiment. The negative coincidence rates of three ELISA screening reagents and neutralization test were all 100%, while the positive coincidence rate of them was 57.14%(12/21)(domestic reagent 1), 66.67%(12/18)(domestic reagent 2), and 27.27%(12/44)(imported reagent), respectively. 2) ROC curve analysis: the optimal HBsAg S/CO values of domestic reagent 1, domestic reagent 2 and imported reagent were 1.635, 3.605 and 3.245, respectively;the sensitivity of the above three reagents was 1, 0.917 and 1, respectively;the specificity was 0.957, 0.978 and 0.761, respectively. 3) Neutralization test confirmed: 12 HBV-positive blood donors were prohibited directly(10 of them were NAT positive), and 46 negative blood donors could be followed up to determine whether they were infected(all 46 were NAT negative).Conclusion The results of this study show that each ELISA reagent has an optimal S/CO value. When the detection result is greater than or equal to this S/CO value, the HBsAg positive rate is higher, which can be directly determined as positive without follow-up confirmation.