Background: Zambia's national HIV testing algorithm specifies use of two rapid blood based antibody assays, DetermineHIV-1/2 (Inverness Medical) and if positive then Uni-Gold Recombigen HIV-1/2 (Trinity Biotech). Little is known about the performance of oral fluid based HIV testing in Zambia. The aims of this study are two-fold: 1) to compare the diagnostic accuracy (sensitivity and specificity) under field conditions of the OraQuick ADVANCE Rapid HIV-1/2 (OraSure Technologies, Inc.) to two blood-based rapid antibody tests currently in use in the Zambia National Algorithm, and 2) to perform a cost analysis of large-scale field testing employing the OraQuick.
Methods: This was a operational retrospective research of HIV testing and questionnaire data collected in 2010 as part of the ZAMSTAR (Zambia South Africa TB and AIDS reduction) study. Randomly sampled individuals in twelve communities were tested consecutively with OraQuick test using oral fluid versus two blood-based rapid HIV tests, Determine and Uni-Gold. A cost analysis of four algorithms from health systems perspective were performed: 1) Determine and if positive, then Uni-Gold (Determine/Uni-Gold); based on current algorithm, 2) Determine and if positive, then OraQuick (Determine/OraQuick), 3) OraQuick and if positive, then Determine (OraQuick/Determine), 4) OraQuick and if positive, then Uni-Gold (OraQuick/Uni-Gold). This information was then used to construct a model using a hypothetical population of 5,000 persons with varying prevalence of HIV infection from 1-30%.
Results: 4,458 participants received both a Determine and OraQuick test. The sensitivity and specificity of the OraQuick test were 98.7 (95%CI, 97.5-99.4) and 99.8 (95%CI, 99.6-99.9), respectively when compared to HIV positive serostatus. The average unit costs per algorithm were US$3.76, US$4.03, US$7.35, and US$7.67 for Determine/Uni-Gold, Determine/OraQuick, OraQuick/Determine, and OraQuick/Uni-Gold, respectively, for an HIV prevalence of 15%.
Conclusions: An alternative HIV testing algorithm could include OraQuick test which had a high sensitivity and specificity. The current Determine/Uni-Gold testing algorithm is the least expensive when compared to Determine/OraQuick, OraQuick/Determine, and OraQuick/Uni-Gold in the Zambian setting. From our field experience, oral fluid based testing offers many advantages over blood-based testing, especially with self testing on the horizon.