AIDS research and human retroviruses 2017 02 14() doi 10.1089/AID.2016.0203
Laboratory tests that can distinguish recent from long-term HIV infection are used to estimate HIV incidence in a population but can potentially misclassify a proportion of long-term HIV infections as recent. Correct application of an assay requires determination of the proportion false recents (PFR) as part of the assay characterization and for calculating HIV incidence in a local population using a HIV incidence assay.
From April 2009 to December 2010, blood specimens were collected from HIV-infected individuals attending 9 outpatient clinics (OPCs) in Vietnam (4 from northern and 5 from southern Vietnam). Participants were living with HIV for ≥1 year and reported no antiretroviral drug (ARV) treatment. Basic demographic data and clinical information were collected. Specimens were tested with the BED capture enzyme immunoassay (BED-CEIA) and the Limiting-antigen (LAg)-Avidity EIA. PFR was estimated by dividing the number of specimens classified as recent by the total number of specimens; 95% confidence intervals (CI) were calculated. Specimens that tested recent had viral load testing performed.
Among 1,813 specimens (north, n= 942 and south, n = 871), the LAg-Avidity EIA PFR was 1.7% (CI 1.2-2.4) and differed by region [north 2.7% (CI 1.8, 3.9) versus south 0.7% (CI 0.3, 1.5); p=0.002]. The BED-CEIA PFR was 2.3% (CI 1.7, 3.0) and varied by region [north 3.4% (CI: 2.4, 4.7) versus south 1.0% (CI 0.5, 1.2), p<0.001]. Excluding specimens with an undetectable VL, the LAg-Avidity EIA PFR was 1.2% (CI: 0.8, 1.9) and the BED-CEIA PFR was 1.7% (CI: 1.2, 2.4). CONCLUSIONS
The LAg-Avidity EIA PFR was lower than the BED-CEIA PFR. After excluding specimens with an undetectable VL, the PFR for both assays was similar. A low PFR should facilitate the implementation of the LAg-Avidity EIA for cross-sectional incidence estimates in Vietnam.