The Ausria test: critical evaluation of sensitivity and specificity

Abstract

Ausria was shown to be considerably more sensitive than counter electrophoresis (CEP) by comparing titers of HBAg+ sera and by testing selected proficiency panels, sera from hepatitis patients, and sera from experimentally infected rhesus monkeys; CEP+, Ausria- sera were never encountered. However, in testing NIH donors and personnel, 19 of 20 Ausria+, CEP- sera were shown by neutralization studies to be nonspecific for HBAg, i.e., false positives. Nonspecificity was confirmed by an alternate radioimmunoassay procedure and, in one serum, by density gradiant ultracentrifugation. Testing of 85 additional Ausria+, Cep- sera from New Jersey donors showed 13 specific and 22 (63%) nonspecific reactions. It is mandatory that serum from every Ausria+, CEP- donor undergo specificity testing. In addition to the 14 specific Ausria+, Cep- sera, two sera, subsequently shown to be CEP+, were undetected on the initial CEP test (one was transfused and resulted in These Tese sera were strongly positive by Ausria; sera subject to reader error in CEP are unequivocally positive by Ausria. Ausria tests on CEP- donors suspected of transmitting HBAg failed to implicate a donor in each of eight cases. Some HBAg+ hepatitis will continue to occur despite universal application of Ausria or other tests of equal sensitivity.