• Designing HIV Testing Algorithms Based on 2015 WHO Guidelines Using Data from Six Sites in sub-Saharan Africa

      Kosack, C; Shanks, L; Beelaert, G; Benson, T; Savane, A; Ng'ang'a, A; Andre, B; Zahinda, J; Fransen, K; Page, A (American Society for Microbiology, 2017-07-26)
      Our objective was to evaluate the performance of HIV testing algorithms based on WHO recommendations, using data from specimens collected at six HIV testing and counselling sites in sub-Saharan Africa (Guinea, Conakry; Kitgum and Arua, Uganda; Homa Bay, Kenya; Douala, Cameroun; Baraka, Democratic Republic of Congo). A total of 2780 samples, including 1306 HIV-positive, were included in the analysis. HIV testing algorithms were designed using Determine as a first test. Second and third rapid diagnostic tests (RDT) were selected based on site-specific performance, adhering where possible to the WHO-recommended minimum requirements of sensitivity and specificity of ≥99%. The threshold for specificity was reduced to 98% or 96% if necessary. We also simulated algorithms consisting of one RDT followed by a simple confirmatory assay. The positive predictive values (PPV) of the simulated algorithms varied from 75.8%-100% using strategies recommended for high-prevalence settings; 98.7%-100% using strategies recommended for low-prevalence settings; and 98.1%-100% using a rapid test followed by a simple confirmatory assay. Although we were able to design algorithms that met the recommended PPV of ≥99% in five of six sites using the applicable high prevalence strategy, options were often very limited due to sub-optimal performance of individual RDTs and to shared false-reactive results. These results underscore the impact of the sequence of HIV tests and of shared false-reactivity on algorithm performance. Where it is not possible to identify tests that meet WHO-recommended specifications, the low-prevalence strategy may be more suitable.
    • HIV Misdiagnosis in Sub-Saharan Africa: Performance of Diagnostic Algorithms at Six Testing Sites

      Kosack, C; Shanks, L; Beelaert, G; Benson, T; Savane, A; Ng'ang'a, A; Andre, B; Zahinda, J; Fransen, K; Page, A (International AIDS Society, 2017-07-03)
      We evaluated the diagnostic accuracy of HIV testing algorithms at six programmes in five sub-Saharan African countries.
    • Response to Comment on "Alert, but not Alarmed" - A Comment on "Towards More Accurate HIV Testing in Sub-Saharan Africa: A Multi-Site Evaluation of HIV RDTs and Risk Factors for False Positives (Kosack et al. 2017)"

      Kosack, C; Page, A; Beelaert, G; Benson, T; Savane, A; Ng'ang'a, A; Andre, B; Zahinda, J; Shanks, L; Fransen, K (International AIDS Society, 2017-06-19)