Results of HBsAg testing of AABB-CAP survey samples.

Participants in the AABB-CAP HBsAg Survey Program and the Comprehensive Blood Bank Survey currently use radioimmunoassay (RIA) as the primary test for hepatitis B surface antigen (HBsAg). In changing from counterimmunoelectrophoresis (CEP) to RIA, participants have maintained a high degree of proficiency, detecting 99.1% of all reactive samples. Both RIA and reversed passive hemagglutination (RPHA) show greater sensitivity than the second-generation methods. Proficiency with RPHA has been variable because of the occurrence of false-positive reactions and difficulty in detecting some samples with RIA ratios between 2.1 and 7.0.