XVIII International AIDS Conference

Abstract

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Validation of four rapid tests for the detection of HIV in Guatemala

T. Velásquez Porta1, B. Samayoa Herrera2, C. Picon3, M. Mazariegos3, C. Motta4, M. Castro5, E. Arathoon6

1Asociacion de Salud Integral, Universidad de San Carlos de Guatemala, Laboratory, Guatemala, Guatemala, 2Asociacion de Salud Integral, Universidad de San Carlos de Guatemala, Guatemala, Guatemala, 3Universidad de San Carlos de Guatemala, Guatemala, Guatemala, 4Asociacion de Salud Integral, Guatemala, Guatemala, 5Programa Nacional de ITS/VIH/Sida Ministerio de Salud Pública Guatemala, Guatemala, Guatemala, 6Asociación de Salud Integral, Guatemala, Guatemala

Background: The access to HIV diagnosis in developing countries is often hindered by high costs of the tests. Therefore, there is a continuous search for new,inexpensive HIV tests. However, it is essential to consider the validity and the reliability of new tests when these are introduced to test a given population. The aim of this work was to demonstrate the performance of four HIV rapid tests in a HIV clinic and in a PMTCT program.
Methods: The 4 rapid tests were provided by the Clinton Foundation. Serum samples were obtained from individuals after signing an informed consent. All sera samples were processed using each of the 4 rapid tests and their results were compared against the reference test, DetermineTM (2503). All positive results for HIV were confirmed by an ELISA test and, if needed, by Western Blot. The data was analyzed with Epi Info 2000 with a 5% alpha. All tests were performed in double-blind with an individual code to avoid any bias. Quality controls were run for positive and negative tests.
Results: A total of 9,732 tests were performed. The global validity and reliability values for each rapid test (sensitivity, specificity, positive predictive value, negative predictive value and Kappa Index) against the reference test were: RetrocheckTM (1948): 96.3%, 99.6%, 91.9%, 99.8%, and 93%; DoubleCheckTM (2009): (98.9%; 99.9%, 98.9%, 99.9% and 98.8%; DipstickTM(1490): 98.5%, 99.9%, 98.5%, 99.9% and 98.4% and for Colloidal GoldTM (1782): 98.5%, 99.5%, 98.5% and 99.9%, 98.4%. These results varied when they were stratified by type of population. Confidence intervals were also obtained for each test.
Conclusions: The rapid tests evaluated are excellent for HIV screening in a high prevalence population but they cannot be used alone. It is necessary to evaluate the performance of these tests if they are intended for HIV testing in other populations.


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