• Causes of false-positive HIV rapid diagnostic test results

      Klarkowski, Derryck; O'Brien, Daniel P; Shanks, Leslie; Singh, Kasha P (Informa Healthcare, 2014-01)
      HIV rapid diagnostic tests have enabled widespread implementation of HIV programs in resource-limited settings. If the tests used in the diagnostic algorithm are susceptible to the same cause for false positivity, a false-positive diagnosis may result in devastating consequences. In resource-limited settings, the lack of routine confirmatory testing, compounded by incorrect interpretation of weak positive test lines and use of tie-breaker algorithms, can leave a false-positive diagnosis undetected. We propose that heightened CD5+ and early B-lymphocyte response polyclonal cross-reactivity are a major cause of HIV false positivity in certain settings; thus, test performance may vary significantly in different geographical areas and populations. There is an urgent need for policy makers to recognize that HIV rapid diagnostic tests are screening tests and mandate confirmatory testing before reporting an HIV-positive result. In addition, weak positive results should not be recognized as valid except in the screening of blood donors.
    • Cost-effectiveness of point-of-care viral load monitoring of antiretroviral therapy in resource-limited settings: mathematical modelling study

      Estill, Janne; Egger, Matthias; Blaser, Nello; Vizcaya, Luisa Salazar; Garone, Daniela; Wood, Robin; Campbell, Jennifer; Hallett, Timothy B; Keiser, Olivia; Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland. jestill@ispm.unibe.ch (Wolters Kluwer Lippincott Williams & Wilkins, 2013-06-01)
      Monitoring of HIV viral load in patients on combination antiretroviral therapy (ART) is not generally available in resource-limited settings. We examined the cost-effectiveness of qualitative point-of-care viral load tests (POC-VL) in sub-Saharan Africa.
    • Eye exam with indirect ophthalmoscopy for diagnosis of disseminated tuberculosis in patients with HIV/AIDS

      Heiden, David; Margolis, Todd P; Lowinger, Alan; Saranchuk, Peter (BMJ Publishing Group, 2013-05-01)
    • False positive HIV diagnoses in resource limited settings: operational lessons learned for HIV programmes

      Shanks, Leslie; Klarkowski, Derryck; O'Brien, Daniel P; Médecins Sans Frontières, Amsterdam, The Netherlands. (Public Library of Science, 2013-03-20)
      Access to HIV diagnosis is life-saving; however the use of rapid diagnostic tests in combination is vulnerable to wrongly diagnosing HIV infection when both screening tests give a false positive result. Misclassification of HIV patients can also occur due to poor quality control, administrative errors and lack of supervision and training of staff. Médecins Sans Frontières discovered in 2004 that HIV negative individuals were enrolled in some HIV programmes. This paper describes the result of an audit of three sites to review testing practices, implement improved testing algorithms and offer re-testing to clients enrolled in the HIV clinic.
    • Prospective Evaluation of the Diagnostic Accuracy of Dried Blood Spots from Finger-Prick for the Determination of HIV-1 Viral Load with the NucliSENS Easy-Q HIV-1 v2.0 in Malawi

      Fajardo, Emmanuel; Metcalf, Carol A; Chaillet, Pascale; Aleixo, Lucia; Pannus, Pieter; Panunzi, Isabella; Triviño, Laura; Ellman, Tom; Likaka, Andrew; Mwenda, Reuben (American Society for Microbiology, 2014-02-05)
      HIV-1 viral load (VL) testing is not widely available in resource-limited settings. Use of finger-prick dried blood spot (FP-DBS) samples could remove barriers related to sample collection and transport. Measurement of VL using DBS from EDTA venous blood (VB-DBS) in place of plasma has previously been validated using the NucliSENS EasyQ HIV-1 v2.0 assay, but information on the accuracy of FP-DBS samples for measuring VL is limited. This prospective study, conducted at Thyolo District Hospital in Southern Malawi, compared VL levels measured on FP-DBS samples and plasma, using the NucliSENS EasyQ HIV-1 v2.0 assay. Comparability was assessed by means of agreement and correlation (131 patients with VLs ≥100 copies/ml), and sensitivity and specificity (612 patients on ART). Samples of EDTA venous blood and FP-DBS from 1,009 HIV-infected individuals were collected and prepared in the laboratory. Bland-Altman analysis found good agreement between plasma and FP-DBS VL levels, with a mean difference of -0.35 log10, and 95% limits of agreement from -1.26 to 0.55 log10. FP-DBS had a sensitivity of 88.7% (95% confidence interval [CI]: 81.1 - 94.4%) and specificity of 97.8% (95% CI: 96.1 - 98.9%) using a 1,000 copies/ml cut-point; and a sensitivity of 83.0% (95% CI: 73.4 - 90.1%) and specificity of 100% (95% CI: 99.3-100%) using a 5,000 copies/ml cut-point. This study shows that FP-DBS is an acceptable alternative to plasma for measuring VL using the NucliSENS EasyQ HIV-1 v2.0. We are conducting a second study to assess the proficiency of health workers at preparing FP-DBS in primary healthcare clinics.
    • Variation in Specificity of HIV Rapid Diagnostic Tests over Place and Time: An Analysis of Discordancy Data Using a Bayesian Approach

      Klarkowski, Derryck; Glass, Kathryn; O'Brien, Daniel; Lokuge, Kamalini; Piriou, Erwan; Shanks, Leslie; Médecins sans Frontières, Operational Centre Amsterdam, Amsterdam, The Netherlands (Public Library of Science, 2013-11)
      Recent trends to earlier access to anti-retroviral treatment underline the importance of accurate HIV diagnosis. The WHO HIV testing strategy recommends the use of two or three rapid diagnostic tests (RDTs) combined in an algorithm and assume a population is serologically stable over time. Yet RDTs are prone to cross reactivity which can lead to false positive or discordant results. This paper uses discordancy data from Médecins Sans Frontières (MSF) programmes to test the hypothesis that the specificity of RDTs change over place and time.