A Simple and Rapid Test-card Method to Detect Hepatitis B Surface Antigen and Antibody: Potential Application in Young Children and Infants.

BACKGROUND Hepatitis B surface antigen (HBsAg) and hepatitis B surface antibody (anti-HBs) were conventionally determined by enzyme immunoassays. We aimed to apply a rapid, simple, and accurate method to detect HBsAg and its antibody. METHODS We collected 1463 serum samples from healthy volunteers, hepatitis B carriers, and children of HBsAg-positive mothers. The test card that we examined is a chromatographic immunoassay for the qualitative detection of either HBsAg or anti-HBs. We then compared the results of the test card to the results of the conventional enzyme-immunoassay method, which is regarded as a standard. RESULTS In the use of the test card to check HBsAg, the sensitivity was 88.8% and the specificity was 100%. The median hepatitis B virus viral load was significantly higher in the true-positive group [10(3.71) copies/mL (range, 10(2)-10(9.03) copies/mL)] than in the false-negative group [10(2) copies/mL (range, 10(2)-10(3.26) copies/mL)] (p = 0.005). In those who were younger than 2 years, the diagnostic accuracy of the HBsAg test card was 100%. Then, 1272 samples were tested for anti-HBs rapid test card. The sensitivity was 91.8% and the specificity was 96.5%. The median anti-HBs titer was significantly higher in the true-positive group (295.8 mIU/mL) than in the false-negative group (42.3 mIU/mL; p < 0.001). CONCLUSION Because of (1) the limited amount of blood sample required and (2) most of the young hepatitis B virus carriers having high viremia, and no concerns of false negativity, the test card is a good rapid screening tool for the detection of HBsAg and anti-HBs in pediatric group.