ELISA法检测HBsAg灰区和单试剂反应性样本的确认结果分析

Verification Tests for the Samples with Suspected ELISA-Positive HBsAg and One-step Testing

目的探讨ELISA法检测HBsAg结果判定灰区设置的必要性,以及中和试验对HBsAg灰区和单试剂反应性样本的确认情况。方法采用两个不同厂家生产的ELISA HBsAg试剂对献血者标本分别进行检测,对检测结果在0.7≤S/CO〈1或单试剂为反应性的标本,再用同种试剂进行双孔复试,双孔中至少有1孔结果仍在灰区内或仍为反应性,留取标本做HBsAg中和试验确证。结果 136例灰区标本中HBsAg中和试验检测出阳性标本10例,阳性率为7.35%,结果异常标本14例;159例单试剂反应性标本中HBsAg中和试验检测出阳性标本19例,阳性率为11.95%,结果异常标本16例。灰区与单试剂反应性样本阳性率的差异没有统计学意义;S/CO值在0.70～0.79区间、0.80～0.89区间、0.90～0.99区间的阳性率有逐渐升高的趋势,但差异无显著性;双试剂灰区的阳性率高于单试剂灰区的阳性率,但差异无统计学意义。结论对HBsAg灰区和单试剂反应性标本,ELISA检测漏检率较高,应结合自己实验室实际设置合适的灰区,最大限度地检出这些可疑标本,并进行确认实验,进一步减少HBsAg漏检和误检率,以提高输血安全,同时避免血源的浪费。

Objective To explore the necessity of confirmative detection for the suspected positivity（grey area）in HBsAg ELISA and one-step tests by neutralization test.Methods The blood samples were individually detected by HBsAg ELISA which were provided by two manufacturers.The results in 0.7≤S/CO〈1 or single reactive samples were checked with the same reagent by double-well tests.The samples with one suspected positive well were subjected to HBsAg neutralization for verification.Results Among 136 samples with suspected positive HBsAg,10（7.35%）were confirmed to be positive by HBsAg neutralization test,and 14 were found to be abnormal.Nineteen of 159 samples that showed positive onestep test gave rise to a confirmed positivity by HBsAg neutralization,and 16 were found to be abnormal.The true positive rate was 11.95%.The value of S/COshowed no obvious difference in positive rates between 0.70～0.79,0.80～0.89,and0.90～0.99.Conclusion The false negative rate of ELISA is high in suspected HBsAg（grey area）and one-step tested samples.Verification tests are necessary to reduce the false negative and misdiagnostic frequencies and to ensure the safty of blood transfusion.