Comparison of rapid test with ELISA for the detection of hepatitis B surface antibodies

ABSTRACT

To compare the sensitivity and specificity of a rapid ICT test with ELISA for the detection of Hepatitis B surface antibody. Cross sectional comparative study conducted at PMRC Specialized Centre for gastroenterology and hepatology JPMC, Karachi from April 2012 - March 2013. A total of 206 apparently healthy adults were selected from a rural community. After taking informed consent, 5 ml blood was collected sera separated and tested for hepatitis B surface antibody [anti-HBs] by a rapid immuno-chromatographic test developed by Korea [Humasis] and ELISA simultaneously. As per manufacturer's guidelines, the rapid ICT test is interpreted as positive if antibody liters are > 30 mIU/ml and negative if the titers are <30 mIU/ml. For ELISA, the CDC interprets antibody titers > 10 mlU/ml as positive or prolective and < 10 mlU/ml as negative and recommends a booster dose. The results of ELISA [gold standard] were compared with rapid test using SPSS version 17.0. Out of 206 sera, using ELISA, anti-HBs was positive in 91[44.2%] sera and negative in 115[55.8%] sera. Using ICT, anti-HBs was positive in 85[41.3%] and negative in 121[58.7%] and the sensitivity and specificity of rapid test ICT was 83.5% and 92.2% respectively with overall accuracy of 88.5%. These figures fell to 70.8% sensitivity and 94.6% specificity with 81.5% accuracy when CDC cut off of 10 mlU/ml was used. The ICT kit gave good results in samples having high liters [> 100 mlU/ml] but had a limited sensitivity for cases having titers between 10 mlU/ml-100 mlU/ml, thus limiting its use and creating unnecessary demand for booster dose of vaccine. The rapid ICT for anti-HBs is not as sensitive as ELISA but can still be used for rapid decision making especially in OPD setups and remote areas