The Optimal Cutoff Value to Predict HIV Infection Using the Architect HIV Ag/Ab Combo

The Architect HIV Ag/Ab Combo has been implemented worldwide as a screening test for more than ten years. However, its high sensitivity may lead to false-positive results in a low-prevalence setting.

This study was carried out to evaluate the performance of the Architect HIV Ag/Ab Combo based on the sample-to-cutoff (S/CO) ratios, to explore the optimal cutoff value to predict HIV infection and reduce the frequency of false-positive results. A retrospective analysis of clinical samples using the Architect HIV Ag/Ab Combo between July 2011 and February 2020 was performed. The sensitivity, specificity, positive predictive value (PPV), and false-positive rate (FPR) were evaluated and the receiver operating characteristic curve (ROC) analysis was used to determine the optimal cutoff value to predict HIV infection.

During the study period, 531 out of 692,155 samples were repeatedly reactive by the Architect HIV Ag/Ab Combo. The median S/CO value of HIV-positive were significantly higher than that of false-positive. The PPV of males (85.68%) was significantly higher than that of females (47.89%). The optimal cutoff value estimated by ROC analysis was 8.96 with the highest sum of sensitivity (100.00%) and specificity (100.00%) for males. However, for females, the optimal cutoff value was 26.97 with the highest sum of sensitivity (100.00%) and specificity (100.00%).

For the Architect HIV Ag/Ab Combo, the optimal cutoff value needs to be set for the different genders to predict the final status of HIV infection reliably.