Could HIV-1 RNA be an option as the second step in the HIV diagnostic algorithm?

BACKGROUND: There is benefit to early HIV-1 diagnosis and treatment, but there is no FDA-approved quantitative assay with a diagnostic claim. We compared the performance of the Hologic Aptima HIV-1 Quant (APT-Quant) and Aptima HIV-1 Qual (APT-Qual) assays for diagnostic use and the performance of a diagnostic algorithm consisting of Bio-Rad BioPlex 2200 HIV Ag-Ab assay (BPC) followed by APT-Quant (two-test) compare to BPC followed by Geenius HIV-1/2 supplemental assay (Geenius) with reflex to APT-Qual (three-test). METHODS: 524 plasma, which included 419 longitudinal specimens from HIV-1 seroconverters (78 were after initiating antiretroviral therapy (ART)) and 105 from ART-naive persons with established HIV-1 infections, were used to evaluate APT-Quant performance for diagnostic use. Specimens from 200 HIV-negative persons were used to measure specificity. For the algorithm comparison, BPC-reactive specimens were evaluated with the two-test or three-test algorithm. McNemar's test was used to compare performance. RESULTS: APT-Quant detected more samples early in infection compared with APT-Qual. APT-Quant specificity was 99.8%. Before ART initiation, the algorithms performed similarly among samples from different stages of infection. After ART initiation, the three-test algorithm performed significantly better (p=0.0233). CONCLUSIONS: APT-Quant has excellent performance for diagnostic use. The two-test algorithm works well in ART-naive samples, but its performance decreases after the IgG response is elicited and with ART-induced suppressed viremia. Providing confirmation and VL with one test result could be advantageous for patient care. However, additional factors and challenges associated with the implementation of this two-test algorithm such as cost, specimen type and collection need further evaluation.