Comparison of the ARCHITECT HIV combo assay signal-to-cutoff (S/Co) for determining recent infection to diagnostic test results.

STOP and LA study specimens were grouped based on the sequence of HIV diagnostic test results or plasma viral loads (VL). Box plots comparing the ARCHITECT HIV Ag/Ab Combo S/Co ratios in the acute and established groups (A), the low (<1,000 RNA copies/mL; N = 298) versus high (>1,000 RNA copies/mL; N = 363) VL groups, and no antiretroviral therapy (ART; N = 370) versus ART-use groups (N = 276) (B) in the STOP and LA study cohorts. The boxes represent the 25th to 75th percentile of the S/Co ratios, while the middle lines represent the median values and whiskers represent the minimum and maximum values. The mean is indicated by “+”. Acute group 1 = ARCHITECT negative, Multispot/Geenius negative or indeterminate, and Aptima/VL reactive. Acute group 2 = ARCHITECT reactive, Multispot/Geenius negative or indeterminate, and Aptima/VL reactive. Established = reactive test result for all three tests.