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

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 counseling sites in sub-Saharan Africa (Conakry, Guinea; Kitgum and Arua, Uganda; Homa Bay, Kenya; Douala, Cameroon; Baraka, Democratic Republic of Congo). A total of 2,780 samples, including 1,306 HIV-positive samples, were included in the analysis. HIV testing algorithms were designed using Determine as a first test. Second and third rapid diagnostic tests (RDTs) were selected based on site-specific performance, adhering where possible to the WHO-recommended minimum requirements of ≥99% sensitivity and specificity. 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 ranged from 75.8% to 100% using strategies recommended for high-prevalence settings, 98.7% to 100% using strategies recommended for low-prevalence settings, and 98.1% to 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 suboptimal performance of individual RDTs and to shared falsely reactive results. These results underscore the impact of the sequence of HIV tests and of shared false-reactivity data on algorithm performance. Where it is not possible to identify tests that meet WHO-recommended specifications, the low-prevalence strategy may be more suitable.

A guide to aid the selection of diagnostic tests.

In recent years, a wide range of diagnostic tests has become available for use in resource-constrained settings. Accordingly, a huge number of guidelines, performance evaluations and implementation reports have been produced. However, this wealth of information is unstructured and of uneven quality, which has made it difficult for end-users, such as clinics, laboratories and health ministries, to determine which test would be best for improving clinical care and patient outcomes in a specific context. This paper outlines a six-step guide to the selection and implementation of in vitro diagnostic tests based on Médecins Sans Frontières' practical experience: (i) define the test's purpose; (ii) review the market; (iii) ascertain regulatory approval; (iv) determine the test's diagnostic accuracy under ideal conditions; (v) determine the test's diagnostic accuracy in clinical practice; and (vi) monitor the test's performance in routine use. Gaps in the information needed to complete these six steps and gaps in regulatory systems are highlighted. Finally, ways of improving the quality of diagnostic tests are suggested, such as establishing a model list of essential diagnostics, establishing a repository of information on the design of diagnostic studies and improving quality control and postmarketing surveillance.

Depuis quelques années, de multiples tests diagnostiques sont disponibles dans les lieux de soins disposant de ressources limitées. En conséquence, un nombre considérable de directives, d'évaluations des performances et de rapports de mise en œuvre ont été élaborés. Cette masse d'informations manque néanmoins de structure et est de qualité inégale, raisons pour lesquelles les utilisateurs finaux, tels que les centres de santé, les laboratoires et les ministères de la Santé, ont eu des difficultés à déterminer quel test conviendrait le mieux pour améliorer les soins cliniques et l'état de santé des patients dans un contexte donné. Ce document présente un guide en six étapes pour faciliter la sélection et la mise en œuvre de tests diagnostiques in vitro, en s'appuyant sur l'expérience pratique de Médecins Sans Frontières: (i) définir l'objectif du test; (ii) analyser le marché; (iii) obtenir l'approbation réglementaire; (iv) déterminer la précision du test diagnostique dans des conditions idéales; (v) déterminer la précision du test diagnostique dans le cadre d'une pratique clinique; et (vi) suivre les performances du test dans le cadre d'une utilisation courante. Ce document met en avant les informations manquantes nécessaires pour accomplir ces six étapes et les lacunes des systèmes de réglementation. Enfin, il propose des moyens d'améliorer la qualité des tests diagnostiques, à travers l'établissement d'une liste modèle des diagnostics essentiels, l'élaboration d'un référentiel d'informations sur la réalisation des études diagnostiques, et l'amélioration du contrôle de la qualité et de la pharmacovigilance.

En los últimos años se ha desarrollado una amplia variedad de pruebas de diagnóstico para el uso en entornos con recursos limitados. Como consecuencia, se ha producido una gran cantidad de manuales, evaluaciones de rendimiento e informes de implementación. No obstante, esta abundancia de información está desestructurada y tiene una calidad irregular. Esto ha dificultado que los usuarios finales, como clínicas, laboratorios y ministerios de salud, puedan determinar qué prueba es la más indicada para mejorar la atención sanitaria y los resultados de los pacientes en un contexto específico. En el presente informe se describe un manual de seis pasos para la selección y la implementación de pruebas de diagnóstico in vitro sobre la base de la experiencia práctica de Mèdecins Sans Frontières: (i) definir el propósito de la prueba; (ii) revisar el mercado; (iii) verificar la aprobación normativa; (iv) determinar la precisión del diagnóstico de la prueba en condiciones ideales; (v) determinar la precisión del diagnóstico de la prueba en la práctica clínica; y (vi) controlar el rendimiento de la prueba en su uso habitual. Se destacan los vacíos en la información necesarios para completar estos seis pasos y los vacíos del sistema normativo. Finalmente, se sugieren maneras para mejorar la calidad de las pruebas de diagnóstico, como establecer una lista modelo de los diagnósticos esenciales, establecer un repositorio de información sobre el diseño de los estudios de diagnósticos y mejorar el control de calidad y el control del postmarketing.

Evaluation of two rapid screening assays for detecting hepatitis C antibodies in resource-constrained settings.

OBJECTIVE: To evaluate the diagnostic accuracy of the OraQuick HCV rapid antibody test from OraSure and the Multisure HCV antibody assay from MP Biomedicals. METHODS: Five seropanels from patients, intravenous drug users and blood donors with and without HCV infection were used on the two rapid immunochromatographic tests. Sensitivity, specificity and predictive values were calculated. In addition, seropanels from 10 seroconverters were used to assess early identification of HCV infection. The study was undertaken in a laboratory at Paul Ehrlich Institute in Germany. RESULTS: Panel 1 contained of 55 positive and 25 negative samples. The OraQuick HCV test had a sensitivity of 100% (95% CI: 93.5-100) and a specificity of 100% (95% CI: 86.3-100). The Multisure HCV test had a sensitivity of 100% (95% CI: 93.5-100) and a specificity of 96% (95% CI: 79.6-99.9). Panel 2 consisted of 193 pre-characterised anti-HCV-positive patient samples. The OraQuick HCV test identified 191 samples correctly and the Multisure HCV 192. The sensitivity was 99.0% (95% CI: 96.3-99.9) for the OraQuick HCV test and 99.5% (95% CI: 97.1-100) for the Multisure HCV test. Panel 3 was composed of seroconversion samples of 10 patients. The OraQuick HCV test detected all of these 10 infections while the Multisure HCV test detected six and was indeterminate on 2. Panel 4 included 53 anti-HCV negative blood samples from blood donors. Both tests correctly identified all 53. Panel 5 consisted of 26 samples of HCV/HIV co-infected patients. The sensitivity of the OraQuick HCV test was 65.2% (95% CI: 42.8-82.8) after 20 min and 73.9% (95% CI: 51.3-88.9) after 40 min of incubation. The Multisure HCV test had a sensitivity of 96.2% (95% CI: 80.4-99.9). CONCLUSION: This evaluation revealed good sensitivity for both rapid screening assays. The detection of seroconverters, however, was lower in the MutiSure HCV test. Therefore the MultiSure test should be used with hesitation in high incidence settings. The OraQuick gave HCV false-negative results in almost 25% of the HIV-positive sera. Therefore may the OraQuick be less suited in HIV prevalent areas.

Routine parallel diagnosis of malaria using microscopy and the malaria rapid diagnostic test SD 05FK60: the experience of Médecins Sans Frontières in Myanmar.

BACKGROUND: Malaria rapid diagnostic tests (RDTs) are commonly used in Médecins Sans Frontières (MSF) programmes to detect acute malaria infection. Programmes in regions with both Plasmodium falciparum and non-falciparum malaria (i.e. Plasmodium ovale, Plasmodium malariae and Plasmodium vivax) use a three-band P. falciparum/Pan test such as the SD Bioline Malaria Ag P.f/Pan 05FK60 (Standard Diagnostics, Kyonggi, Republic of Korea), hereafter referred to as SD 05FK60, as used by the MSF-Holland clinics in Rakhine state, Myanmar. In spite of published reports of generally good test performance, medical and paramedical staff on the ground often doubt the diagnostic accuracy of these RDTs. METHODS: Parallel testing with malaria microscopy and RDT was conducted at two clinics in Rakhine state, Myanmar, for a period of 14 months as a programmatic response due to doubts and concerns of medical and paramedical staff into malaria RDTs. RESULTS: A total of 2,585 blood samples from non-pregnant suspected malaria patients were examined by the SD 05FK60 RDT and microscopy at two clinics in Myanmar from October 2010 to December 2011. The reference standard microscopy diagnosed 531 P. falciparum and 587 P. vivax or P. malariae mono-infections. The overall sensitivity for P. falciparum detection by the SD 05FK60 was 90.2% (95% CI: 87.4-92.6) and for P. vivax/P. malariae 79.4% (95% CI: 75.9-82.6). The overall specificity for P. falciparum detection by the SD 05FK60 was 98.5% (95% CI: 97.7-99.1) and for P. vivax/P. malariae 98.7% (95% CI: 97.9-99.2). The sensitivity for P. falciparum was >91% for parasitaemia levels of >100-1,000 parasites/µl and increased for P. vivax/P. malariae with the parasitaemia level but was overall lower than for P. falciparum 25/408 and 13/420 cases, respectively, of P. falciparum and non-falciparum malaria were missed by the RDT. CONCLUSION: In field conditions in Myanmar, the SD 05FK60 malaria RDT performed consistent with other reports. The test detected malaria caused by P. vivax/P. malariae to a lesser extent than P. falciparum infection. Sensitivity improved with increasing parasitaemia level, however even at higher levels some infections were missed. The SD 05FK60 is adequate for use in settings where high quality microscopy is not available.

Feasibility of using teleradiology to improve tuberculosis screening and case management in a district hospital in Malawi.

PROBLEM: Malawi has one of the world's highest rates of human immunodeficiency virus (HIV) infection (10.6%), and southern Malawi, where Thyolo district is located, bears the highest burden in the country (14.5%). Tuberculosis, common among HIV-infected people, requires radiologic diagnosis, yet Malawi has no radiologists in public service. This hinders rapid and accurate diagnosis and increases morbidity and mortality. APPROACH: Médecins Sans Frontières, in collaboration with Malawi's Ministry of Health, implemented teleradiology in Thyolo district to assist clinical staff in radiologic image interpretation and diagnosis. LOCAL SETTING: Thyolo district's 600 000 inhabitants are mostly subsistence-level or migrant farmers living in extreme poverty. Health facilities include one public hospital and 38 primary health centres. Understaffing and the absence of a radiologist make the diagnosis of tuberculosis difficult in a population where this disease affects 66% of patients with HIV infection. RELEVANT CHANGES: From September 2010-2011, 159 images (from 158 patients) were reviewed by teleradiology. Teleradiology changed patient management in 36 cases (23.5%). Two (1.3%) of them were cases of pulmonary tuberculosis not previously suspected by clinical staff. In addition, the radiologist's review corrected the misdiagnosis of tuberculosis and averted inappropriate treatment in 16 patients (10.5%). LESSONS LEARNT: Teleradiology can improve tuberculosis diagnosis and case management, especially if criteria to identify the patients most suitable for referral are developed and the radiologist is conversant with local resources and health problems. Designating a clinical focal point for teleradiology ensures sustainability. Staff need time to adapt to a new teleradiology programme.

Experience of Médecins Sans Frontières in laboratory medicine in resource-limited settings.

In medical humanitarian assistance, the diagnosis of diseases plays a crucial role. Laboratory investigations are one of the main diagnostic tools utilized in Médecins Sans Frontières' (MSF) programs. Currently MSF supports and/or operates more than 130 laboratories in approximately 45 countries. The variety of analysis offered depends largely on the context of the program and the availability of context adapted tools and ranges from sophisticated laboratories specializing in tuberculosis culture to small laboratories within a primary health care program or operating as mobile clinics. The largest laboratories in MSF are found in programs with the main objective to diagnose, treat and monitor patients with tuberculosis and/or human immunodeficiency virus. Other MSF programs are either disease-specific (e.g., malaria, Chagas, kala azar or visceral leishmaniasis, sleeping sickness, malnutrition, sexually transmitted infections) or are integrated in primary or secondary health care structures.

HIV misdiagnosis in sub-Saharan Africa: performance of diagnostic algorithms at six testing sites.

INTRODUCTION: We evaluated the diagnostic accuracy of HIV testing algorithms at six programmes in five sub-Saharan African countries. METHODS: In this prospective multisite diagnostic evaluation study (Conakry, Guinea; Kitgum, Uganda; Arua, Uganda; Homa Bay, Kenya; Doula, Cameroun and Baraka, Democratic Republic of Congo), samples from clients (greater than equal to five years of age) testing for HIV were collected and compared to a state-of-the-art algorithm from the AIDS reference laboratory at the Institute of Tropical Medicine, Belgium. The reference algorithm consisted of an enzyme-linked immuno-sorbent assay, a line-immunoassay, a single antigen-enzyme immunoassay and a DNA polymerase chain reaction test. RESULTS: Between August 2011 and January 2015, over 14,000 clients were tested for HIV at 6 HIV counselling and testing sites. Of those, 2786 (median age: 30; 38.1% males) were included in the study. Sensitivity of the testing algorithms ranged from 89.5% in Arua to 100% in Douala and Conakry, while specificity ranged from 98.3% in Doula to 100% in Conakry. Overall, 24 (0.9%) clients, and as many as 8 per site (1.7%), were misdiagnosed, with 16 false-positive and 8 false-negative results. Six false-negative specimens were retested with the on-site algorithm on the same sample and were found to be positive. Conversely, 13 false-positive specimens were retested: 8 remained false-positive with the on-site algorithm. CONCLUSIONS: The performance of algorithms at several sites failed to meet expectations and thresholds set by the World Health Organization, with unacceptably high rates of false results. Alongside the careful selection of rapid diagnostic tests and the validation of algorithms, strictly observing correct procedures can reduce the risk of false results. In the meantime, to identify false-positive diagnoses at initial testing, patients should be retested upon initiating antiretroviral therapy.

Towards more accurate HIV testing in sub-Saharan Africa: a multi-site evaluation of HIV RDTs and risk factors for false positives.

INTRODUCTION: Although individual HIV rapid diagnostic tests (RDTs) show good performance in evaluations conducted by WHO, reports from several African countries highlight potentially significant performance issues. Despite widespread use of RDTs for HIV diagnosis in resource-constrained settings, there has been no systematic, head-to-head evaluation of their accuracy with specimens from diverse settings across sub-Saharan Africa. We conducted a standardized, centralized evaluation of eight HIV RDTs and two simple confirmatory assays at a WHO collaborating centre for evaluation of HIV diagnostics using specimens from six sites in five sub-Saharan African countries. METHODS: Specimens were transported to the Institute of Tropical Medicine (ITM), Antwerp, Belgium for testing. The tests were evaluated by comparing their results to a state-of-the-art reference algorithm to estimate sensitivity, specificity and predictive values. RESULTS: 2785 samples collected from August 2011 to January 2015 were tested at ITM. All RDTs showed very high sensitivity, from 98.8% for First Response HIV Card Test 1-2.0 to 100% for Determine HIV 1/2, Genie Fast, SD Bioline HIV 1/2 3.0 and INSTI HIV-1/HIV-2 Antibody Test kit. Specificity ranged from 90.4% for First Response to 99.7% for HIV 1/2 STAT-PAK with wide variation based on the geographical origin of specimens. Multivariate analysis showed several factors were associated with false-positive results, including gender, provider-initiated testing and the geographical origin of specimens. For simple confirmatory assays, the total sensitivity and specificity was 100% and 98.8% for ImmunoComb II HIV 12 CombFirm (ImmunoComb) and 99.7% and 98.4% for Geenius HIV 1/2 with indeterminate rates of 8.9% and 9.4%. CONCLUSION: In this first systematic head-to-head evaluation of the most widely used RDTs, individual RDTs performed more poorly than in the WHO evaluations: only one test met the recommended thresholds for RDTs of ≥99% sensitivity and ≥98% specificity. By performing all tests in a centralized setting, we show that these differences in performance cannot be attributed to study procedure, end-user variation, storage conditions, or other methodological factors. These results highlight the existence of geographical and population differences in individual HIV RDT performance and underscore the challenges of designing locally validated algorithms that meet the latest WHO-recommended thresholds.

Implementing the Xpert® MTB/RIF Diagnostic Test for Tuberculosis and Rifampicin Resistance: Outcomes and Lessons Learned in 18 Countries.

BACKGROUND: The Xpert® MTB/RIF (Xpert) is an automated molecular test for simultaneous detection of tuberculosis (TB) and rifampicin resistance, recommended by the World Health Organization as the preferred diagnostic method for individuals presumed to have multi-drug resistant TB (MDR-TB) or HIV-associated TB. We describe the performance of Xpert and key lessons learned during two years of implementation under routine conditions in 33 projects located in 18 countries supported by Médecins Sans Frontières across varied geographic, epidemiological and clinical settings. METHODS: Xpert was used following three strategies: the first being as the initial test, with microscopy in parallel, for all presumptive TB cases; the second being only for patients at risk of MDR-TB, or with HIV- associated TB, or presumptive paediatric TB; and the third being as the initial test for these high-risk patients plus as an add-on test to microscopy in others. Routine laboratory data were collected, using laboratory registers. Qualitative data such as logistic aspects, human resources, and tool acceptance were collected using a questionnaire. FINDINGS: In total, 52,863 samples underwent Xpert testing from April 2011 to December 2012. The average MTB detection rate was 18.5%, 22.3%, and 11.6% for the three different strategies respectively. Analysis of the results on samples tested in parallel showed that using Xpert as add-on test to microscopy would have increased laboratory TB confirmation by 49.7%, versus 42.3% for Xpert replacing microscopy. The main limitation of the test was the high rate of inconclusive results, which correlated with factors such as defective modules, cartridge version (G3 vs. G4) and staff experience. Operational and logistical hurdles included infrastructure renovation, basic computer training, regular instrument troubleshooting and maintenance, all of which required substantial and continuous support. CONCLUSION: The implementation of Xpert was feasible and significantly increased TB detection compared to microscopy, despite the high rate of inconclusive results. Xpert implementation was accompanied by considerable operational and logistical challenges. To further decentralize diagnosis, simpler, low-cost TB technologies well-suited to low-resource settings are still urgently needed.

Diagnostic accuracy evaluation of the ImmunoFlow HCV rapid immunochromatographic test for the detection of hepatitis C antibodies.

2% of the world's population lives with a hepatitis C virus (HCV) infection with highest rates in developing countries. The most common mode of transmission takes place via unsafe blood transfusions and unsafe therapeutic injections. Thus, screening potential blood donors for hepatitis C infection is a must to ensure safe blood transfusions. Rapid immunochromatographic tests are the best suitable test format to be used for screening for blood donors in resource-limited settings. The ImmunoFlow HCV from Core Diagnostics was evaluated at the Paul-Ehrlich-Institute, Germany for its test accuracy on three seropanels. Panel 1 consisted of 26 HCV positive and 55 negative samples, panel 2 of 193 HCV positive samples. Panel 3 contained 116 samples of 10 patients during seroconversion period. 39 of these 116 samples were characterized as HCV positive. The HCV ImmunoFlow had a sensitivity of 100% (95% CI: 93.5-100) and a specificity of 100% (95% CI: 86.8-100) when samples of panel 1 were tested. 191 samples of the 193 samples in panel 2 were correctly by the HCV Immunoflow, resulting in a sensitivity of 99.0%. 9 of 10 HCV infections were detected by the HCV ImmunoFlow when panel 3 was used. This evaluation revealed good sensitivity of the HCV ImmunoFlow test from and compares favorably with the results from the WHO evaluation and a systematic review conducted of field evaluations of Hepatitis C rapid diagnostic and other point of care tests.

TSH-CHECK-1 test: diagnostic accuracy and potential application to initiating treatment for hypothyroidism in patients on anti-tuberculosis drugs.

BACKGROUND: Thyroid-stimulating hormone (TSH) promotes expression of thyroid hormones which are essential for metabolism, growth, and development. Second-line drugs to treat tuberculosis (TB) can cause hypothyroidism by suppressing thyroid hormone synthesis. Therefore, TSH levels are routinely measured in TB patients receiving second-line drugs, and thyroxin treatment is initiated where indicated. However, standard TSH tests are technically demanding for many low-resource settings where TB is prevalent; a simple and inexpensive test is urgently needed. METHODS: As a proof of concept study TSH was measured in routinely collected sera at the University Medical Center Utrecht, Netherlands, using the TSH-CHECK-1 (VEDALAB, Alençon, France), a lateral-flow rapid immunochromatographic assay with a TSH cut-off value of 10 µIU/mL, the standard threshold for initiating treatment. These results were compared with TSH levels measured by a reference standard (UniCel DXi 800 imunoassay system, Beckman Coulter, USA). Sensitivity, specificity, and likelihood ratios were then calculated. RESULTS: A total of 215 serum samples were evaluated: 107 with TSH values <10 µIU/mL and 108 with values ≥10 µIU/mL. TSH-CHECK-1 test sensitivity was found to be 100.0% (95% CI: 96.6-100.0) and specificity was 76.6% (95% CI: 67.5-84.3). Predictive values (PV) were modelled for different levels of prevalence. For a prevalence of 10% and 50%, the positive PV was 32.2% (95% CI: 25.0-39.7%) and 81.1% (95% CI: 75.0-85.5%), respectively; the negative PV was 100% (95% CI: 98.9-100%) and 100% (95% CI: 91.3-100%) respectively. DISCUSSION/CONCLUSIONS: The TSH-CHECK-1 rapid test was practical and simple to perform but difficult to interpret on weak positive results. All sera with TSH≥10 µIU/mL were correctly identified, but the test lacked sufficient specificity. Given its excellent negative PV in this evaluation, the test shows promise for ruling out hypothyroidism. However, so far it appears that samples testing positive with TSH-CHECK-1 would require confirmation using another method.