Sensitivity and specificity of OraQuick® HIV self-test compared to a 4th generation laboratory reference standard algorithm in urban and rural Zambia

Abstract

Background: HIV self-testing (HIVST) has the potential to increase coverage of HIV testing, but concerns exist about intended users’ ability to correctly perform and interpret tests, especially in poor communities with low literacy rates. We assessed the clinical performance of the 2016 prototype OraQuick® HIV Self-Test in rural and urban communities in Zambia to assess the sensitivity and specificity of the test compared to the national HIV rapid diagnostic test (RDT) algorithm and a laboratory reference standard using 4th generation enzyme immunoassays and HIV RNA detection. Methods: Participants were recruited from randomly selected rural and urban households and one urban health facility between May 2016 and June 2017. Participants received a brief demonstration of the self-test, and then self-tested without further assistance. The research team re-read the self-test, repeated the self-test, drew blood for the laboratory reference, and conducted RDTs following the national HIV testing algorithm (Determine™ HIV1/2 (Alere) confirmed using Unigold™ HIV1/2 (Trinity Biotech)). Selected participants (N = 85) were videotaped whilst conducting the testing to observe common errors. Results: Initial piloting showed that written instructions alone were inadequate, and a demonstration of self-test use was required. Of 2,566 self-test users, 2,557 (99.6%) were able to interpret their result. Of participants who were videoed 75/84 (89.3%) completed all steps of the procedure correctly. Agreement between the user-read result and the researcher-read result was 99.1%. Compared to the RDT algorithm, user-conducted HIVST was 94.1% sensitive (95%CI: 90.2–96.7) and 99.7% specific (95%CI: 99.3–99.9). Compared to the laboratory reference, both user-conducted HIVST (sensitivity 87.5%, 95%CI: 82.70–91.3; specificity 99.7%, 95%CI: 99.4–99.9) and the national RDT algorithm (sensitivity 93.4%, 95%CI: 89.7–96.1%; specificity 100% (95%CI: 99.8–100%) had considerably lower sensitivity. Conclusions: Self-testers in Zambia who used OraQuick® HIV Self-Test achieved reasonable clinical performance compared to the national RDT algorithm. However, sensitivity of the self-test was reduced compared to a laboratory reference standard, as was the national RDT algorithm. In-person demonstration, along with the written manufacturer instructions, was needed to obtain accurate results. Programmes introducing self-care diagnostics should pilot and optimise support materials to ensure they are appropriately adapted to context.