Simplified and less expensive confirmatory HIV testing.

The conventional approach to human immunodeficiency virus (HIV) antibody testing, which relies on confirmation of all initially positive screening results using a Western blot assay, is expensive. In an alternative approach, we retested sera that were positive in an initial screening assay using a second screening assay, which differed from the first, and limited the use of Western blot to those sera that gave discrepant results in the two screening assays. This resulted in 100% sensitivity and specificity at a cost that was, on average, 6.1 times less than that of the conventional approach. This level of sensitivity and specificity was also achieved at a cost that was 9.0 times less than the conventional approach if the Western blot was replaced by a third screening assay that differed from the previous two. Retesting positive sera using the same assay did not increase the accuracy of the results obtained by testing the sera only once.After HIV antibodies had been detected by various assays in the sera of 164 people (Europeans, Africans, and South Americans), microbiologists from the Institute of Tropical Medicine in Antwerp, Belgium used simple and inexpensive assays to confirm HIV infection. They retested sera that were positive in the 1st screening with a different assay. They used the Western blot assay only if contradictory results occurred in the 2 assays. The alternative approach developed 100% sensitivity and specificity. Further the cost of this approach averaged 6.1 times less than if they confirmed positive results with the Western blot and 9 times less than if they used this conventional approach if a 3rd assay, different from the 2 previous assays, replaced the Western blot. In addition, when the researchers retested positive sera with the same assay as the 1st, the accuracy of the results did not improve. In fact, the researchers highlighted that the 1st assay should be more sensitive than the following assays, since the 1st assay is the factor that limits the sensitivity of the combination. Researchers should follow this study with similar research in resource limited settings with different epidemiologic patterns of HIV seroprevalence. In conclusion, this alternative approach may result in accurate, less expensive, more rapid and/or less equipment reliant testing for HIV infection.