A signal-to-cutoff ratio in the Abbott architect HIV Ag/Ab Combo assay that predicts subsequent confirmation of HIV-1 infection in a low-prevalence setting

A rapid diagnosis is considered important in HIV care. In 138,911 testing episodes with the Abbott Architect HIV Ag/Ab Combo assay (3,705 reactive samples), a signal-to-cutoff ratio of >151.17 had a positive predictive value of 100% and a sensitivity of 67.4% for the detection of subsequently confirmed HIV infection. We suggest that results higher than this signal-to-cutoff ratio threshold may be reported to clinicians before the completion of confirmatory testing.