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

Laboratory-based evaluation of the 4th-generation AlereTM HIV Combo rapid point-of-care test

BACKGROUND

Mozambique is a high-prevalence country for HIV and early detection of new HIV infections is crucial for control of the epidemic. We aimed to evaluate the accuracy of the 4th-generation rapid diagnostic test (RDT) AlereTM HIV Combo in detecting acute and seroconverted HIV-infection, among sexually-active women attending three clinical health centers in Maputo, Mozambique.

METHODS

Women aged 14-55 years (n = 920) seeking care at the Mavalane Health Area, Maputo (February 2018-January 2019) were included, and blood specimens sampled. Sociodemographic and sexual behavior data were collected. Point-of-care HIV testing was performed using Alere DetermineTM HIV-1/2 and Uni-GoldTM HIV-1/2. All samples were also tested using Enzygnost® HIV Integral 4 and Innotest® HIV Antigen mAb in laboratory. The 4th-generation RDT AlereTM HIV Combo was evaluated on serum samples in the laboratory. Finally, Innotest® HIV Antigen mAb, Enzygnost® HIV Integral 4 (Ag/Ab), and HIV RNA quantification acted as gold standard assays in the evaluation of AlereTM HIV Combo test for HIV antigen detection (in clinical samples and in three HIV-1 seroconversion panels).

RESULTS

The antibody component of the 4th generation AlereTM HIV Combo RDT demonstrated a sensitivity and specificity of 100% examining clinical samples. However, the test did not detect HIV p24 antigen in any clinical samples, while Innotest® HIV Antigen mAb, verified by Enzygnost® HIV Integral 4 (Ag/Ab) and/or HIV RNA quantification, detected HIV antigen in six clinical samples. Furthermore, the AlereTM HIV Combo RDT had a low sensitivity in the detection of HIV p24 antigen in seroconversion panels. The HIV prevalence among the examined women was 17.8%.

CONCLUSIONS

The 4th-generation RDT AlereTM HIV Combo showed similar sensitivity to the 3rd-generation RDTs to detect seroconverted HIV-infections. However, the sensitivity for detection of HIV p24 antigen and diagnosing acute HIV infections, before seroconversion, was low. There is an urgent need to develop and evaluate simple and affordable POC tests with high sensitivity and specificity for diagnosing individuals with acute HIV infection in resource-limited settings with high HIV prevalence.

Treatment-adjusted prevalence to assess HIV testing programmes

Scale-up of human immunodeficiency virus (HIV) testing and antiretroviral therapy (ART) for people living with HIV has been increasing in sub-Saharan Africa. As a result, areas with high HIV prevalence are finding a declining proportion of people testing positive in their national testing programmes. In eastern and southern Africa, where there are settings with adult HIV prevalence of 12% and above, the positivity from national HIV testing services has dropped to below 5%. Identifying those in need of ART is therefore becoming more costly for national HIV programmes. Annual target-setting assumes that national testing positivity rates approximate that of population prevalence. This assumption has generated an increased focus on testing approaches which achieve higher rates of HIV positivity. This trend is a departure from the provider-initiated testing and counselling strategy used early in the global HIV response. We discuss a new indicator, treatment-adjusted prevalence, that countries can use as a practical benchmark for estimating the expected adult positivity in a testing programme when accounting for both national HIV prevalence and ART coverage. The indicator is calculated by removing those people receiving ART from the numerator and denominator of HIV prevalence. Treatment-adjusted prevalence can be readily estimated from existing programme data and population estimates, and in 2019, was added to the World Health Organization guidelines for HIV testing and strategic information. Using country examples from Kenya, Malawi, South Sudan and Zimbabwe we illustrate how to apply this indicator and we discuss the potential public health implications of its use from the national to facility level.

The evolving HIV epidemic and its impact on the HIV testing algorithm: Is it time to change the HIV testing algorithm in South Africa?

HIV-1/2 testing is the first step in ensuring HIV-infected individuals are diagnosed and appropriately managed. The impact of suboptimal HIV-1/2 testing algorithms significantly contributes to the increased rates of misdiagnosis of HIV infection. Recently, the World Health Organization (WHO) recommended that high burden countries revise their testing algorithm from a 2 to 3-test testing strategy in the context of an evolving HIV epidemic. Implementation of a new HIV-testing algorithm must be tailor-made within a national framework and must be balanced out with operational feasibility, patient outcomes, and cost-effectiveness. In this review, we provide an overview of the current state of the HIV epidemic and its impact on HIV testing, further we highlight areas of concern in changing from a 2-step to a 3-step test algorithm in the context of South Africa's HIV epidemic and public health program.

HIV-1 diagnosis using dried blood spots from patients in Kinshasa, DRC: a tool to detect misdiagnosis and achieve World Health Organization 2030 targets

INTRODUCTION

Currently, only 54% of the population of the Democratic Republic of the Congo (DRC) know their HIV status. The aim of this study was to detect HIV misdiagnosis from rapid diagnostic tests (RDT) and to evaluate serological immunoassays using dried blood spots (DBS) from patients in Kinshasa, DRC.

METHODS

Between 2016 and 2018, 365 DBS samples were collected from 363 individuals and shipped to Spain. The samples were from people with a new HIV positive (n = 123) or indeterminate (n = 23) result, known HIV-positive patients (n = 157), and a negative control group (n = 62). HIV serology was performed using Elecsys HIV combi PT (Roche), VIDAS HIV Duo Quick (BioMérieux), and Geenius (Bio-Rad). In addition, HIV RNA detection was performed in all samples using the COBAS AmpliPrep/COBAS Taqman HIV-1 Test 2.0 (Roche).

RESULTS

Overall, 272 samples were found to be positive and 93 to be negative for HIV serology. The sensitivity was 100% for both Elecsys and VIDAS techniques, but specificity was slightly higher for the VIDAS test: 100% (96.1-100%) vs 98.9% (94.1-99.9%). Of the 23 indeterminate cases using RDT, only three cases were true-positives with a detectable viral load. Eleven samples out of the 280 classified as positive by RDT corresponded to nine patients who had received a false diagnosis of HIV through RDT (3.9%); six of them had been on antiretroviral therapy for at least 2 years.

CONCLUSIONS

Elecsys HIV combi PT and VIDAS HIV Duo Quick immunoassays showed high sensitivity and specificity when using DBS. RDT-based serological diagnosis can lead to HIV misdiagnosis with personal and social consequences in sub-Saharan Africa.

Point-of-care tests detecting HIV nucleic acids for diagnosis of HIV-1 or HIV-2 infection in infants and children aged 18 months or less

BACKGROUND

The standard method of diagnosing HIV in infants and children less than 18 months is with a nucleic acid amplification test reverse transcriptase polymerase chain reaction test (NAT RT-PCR) detecting viral ribonucleic acid (RNA). Laboratory testing using the RT-PCR platform for HIV infection is limited by poor access, logistical support, and delays in relaying test results and initiating therapy in low-resource settings. The use of rapid diagnostic tests at or near the point-of-care (POC) can increase access to early diagnosis of HIV infection in infants and children less than 18 months of age and timely initiation of antiretroviral therapy (ART).

OBJECTIVES

To summarize the diagnostic accuracy of point-of-care nucleic acid-based testing (POC NAT) to detect HIV-1/HIV-2 infection in infants and children aged 18 months or less exposed to HIV infection.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (until 2 February 2021), MEDLINE and Embase (until 1 February 2021), and LILACS and Web of Science (until 2 February 2021) with no language or publication status restriction. We also searched conference websites and clinical trial registries, tracked reference lists of included studies and relevant systematic reviews, and consulted experts for potentially eligible studies.

SELECTION CRITERIA

We defined POC tests as rapid diagnostic tests conducted at or near the patient site. We included any primary study that compared the results of a POC NAT to a reference standard of laboratory NAT RT-PCR or total nucleic acid testing to detect the presence or absence of HIV infection denoted by HIV viral nucleic acids in infants and children aged 18 months or less who were exposed to HIV-1/HIV-2 infection. We included cross-sectional, prospective, and retrospective study designs and those that provided sufficient data to create the 2 × 2 table to calculate sensitivity and specificity. We excluded diagnostic case control studies with healthy controls.

DATA COLLECTION AND ANALYSIS

We extracted information on study characteristics using a pretested standardized data extraction form. We used the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies) tool to assess the risk of bias and applicability concerns of the included studies. Two review authors independently selected and assessed the included studies, resolving any disagreements by consensus. The unit of analysis was the participant. We first conducted preliminary exploratory analyses by plotting estimates of sensitivity and specificity from each study on forest plots and in receiver operating characteristic (ROC) space. For the overall meta-analyses, we pooled estimates of sensitivity and specificity using the bivariate meta-analysis model at a common threshold (presence or absence of infection).

MAIN RESULTS

We identified a total of 12 studies (15 evaluations, 15,120 participants). All studies were conducted in sub-Saharan Africa. The ages of included infants and children in the evaluations were as follows: at birth (n = 6), ≤ 12 months (n = 3), ≤ 18 months (n = 5), and ≤ 24 months (n = 1). Ten evaluations were field evaluations of the POC NAT test at the point of care, and five were laboratory evaluations of the POC NAT tests.The POC NAT tests evaluated included Alere q HIV-1/2 Detect qualitative test (recently renamed m-PIMA q HIV-1/2 Detect qualitative test) (n = 6), Xpert HIV-1 qualitative test (n = 6), and SAMBA HIV-1 qualitative test (n = 3). POC NAT pooled sensitivity and specificity (95% confidence interval (CI)) against laboratory reference standard tests were 98.6% (96.1 to 99.5) (15 evaluations, 1728 participants) and 99.9% (99.7 to 99.9) (15 evaluations, 13,392 participants) in infants and children ≤ 18 months. Risk of bias in the included studies was mostly low or unclear due to poor reporting. Five evaluations had some concerns for applicability for the index test, as they were POC tests evaluated in a laboratory setting, but there was no difference detected between settings in sensitivity (-1.3% (95% CI -4.1 to 1.5)); and specificity results were similar.

AUTHORS' CONCLUSIONS

For the diagnosis of HIV-1/HIV-2 infection, we found the sensitivity and specificity of POC NAT tests to be high in infants and children aged 18 months or less who were exposed to HIV infection.

Country adherence to WHO recommendations to improve the quality of HIV diagnosis: a global policy review

Introduction

Ensuring a correct and timely HIV diagnosis is critical. WHO publishes guidelines on HIV testing strategies that maximise the likelihood of correctly determining one’s HIV status. A review of national HIV testing policies in 2014 found low adherence to WHO guidelines. We updated this review to determine adherence to current recommendations.

Methods

We conducted a comprehensive policy review through April 2018. We extracted data on HIV testing strategies, recommendations on HIV retesting prior to antiretroviral therapy (ART) initiation and pre-exposure prophylaxis (PrEP)-related HIV testing information. Descriptive analyses disaggregated by region were conducted to ascertain adherence to recommendations and to describe testing strategy characteristics.

Results

Of 91 policies included, 26% (n=24/91) adhered to WHO recommendations. Having a two-assay testing strategy to rule-in HIV infection as opposed to the recommended three-assay testing strategy was a major reason for non-adherence. Of 72 country policies providing sufficient information, 31% (n=22) recommended retesting for HIV prior to initiating ART. Of 25 countries and two regions reporting PrEP-related HIV testing guidelines, almost all recommended testing prior to initiating PrEP and every 3 months during PrEP use.

Conclusions

Global adherence to WHO recommendations for HIV testing strategies have improved since 2014 but remain low. We found adherence existed on a continuum. Such a system provides insights into how countries can move towards adherence by making relatively minor changes to testing strategies. Guidance from WHO on the role of new HIV testing technologies within testing algorithms and identifying ways to simplify testing guidance is warranted.

Rapid Testing Algorithm Performance in a Low-Prevalence Environment

BACKGROUND

The performance of a statewide HIV rapid test algorithm (RTA) in a low-prevalence setting (0.71%) was examined for 3 years.

METHODS

An initial rapid screening by HIV-1/2 Ag/Ab Combo test (RT#1) with Ab verification using a second, different rapid test (RT#2) was conducted. Clinic referral was immediate for antigen-only-positive screens. Antibody-positive screens were confirmed by RT#2. Specimens were collected following discordant RTA results (initially Ab-POS by RT#1, but negative on RT#2) and tested in accordance with the current Centers for Disease Control and Prevention/Association of Public Health Laboratories-based HIV diagnostic algorithm supplemented by a quantitative viral load whenever possible.

RESULTS

Of 310,785 tests performed, 2400 preliminary positive screens were identified; 2191 (91.8%) confirmed by RT#2. Of 13 Determine Combo AG-POS results identified, only 1 confirmed positive. Of the remaining 196 discordant results, 182 (92.9%) were uninfected, including 13 with AG-POS/AB-POS results. Of 14 true positives (7.1%) identified after discordant RTA results, the average quantitative HIV-1 viral load was 277,385 copies/mL, but 5 (35.7%) of 14 had viral loads <1000 copies/mL. Among the 2191 "presumptive positive" by RTA, 3 false-positive (FP) RTAs were reported (both rapid tests having positive results, while the HIV-1/2 Ag/Ab assay and quantitative HIV-1 viral load showed negative results).

CONCLUSIONS

The RTA was effective in predicting true-positive HIV test results and facilitating linkage to care. Discordant results were infrequent. Fingerstick DC Ag detection identified a single early infection. Many discordant cases that were subsequently positive were associated with viral loads <1000 copies/mL.

The rapid CD4 + T-lymphocyte decline and human immunodeficiency virus progression in females compared to males

CD4 + T-lymphocyte counts are used to assess CD4 + decline and the stage of human immunodeficiency virus (HIV) progression in HIV-infected patients. Clinical observation suggests that HIV progress more rapid in females than males. Of the original 5000 HIV-infected population of Western New York HIV/AIDS, Referral Center at Erie County Medical Center (ECMC), 1422 participated in the cohort study. We identified 333 HIV-infected patients with CD4 + T-cell-counts ≥ 500/µƖ, among them 178 met the inclusion criteria for the 10-year study. Females had higher mode (600 vs. 540) and mean (741.9 vs. 712.2) CD4 + counts than males at baseline. However, CD4 + declined faster among females in a shorter time than males (234.5 vs. 158.6, P < 0.004), with rapid HIV progression. Univariate analyses determined that females had a 40% higher risk for CD4 + decline than males. The bivariate analyses specified CD4 + decline remained greater in females than males. Multivariate analyses which employed Cox’s proportional Hazard-Model to adjust for numerous variables simultaneously identified women had almost twice the risk for CD4 + decline and rapid HIV progression than males (RR = 1.93; 95%CI 1.24, 2.99). Although the biological mechanism remains unknown, findings suggest gender differences in CD4 + decline, with a higher risk of rapid HIV progression and shorter longevity in females.

Diagnostic Performances of Three Rapid Diagnostic Tests for Detecting HIV Infections in Mali

Diagnosis of HIV infections in resource-limited countries like Mali is based on Rapid Diagnostic Tests (RDTs). The RDTs are diagnostic assays designed for use at the Point-Of-Care (POC), which is quick, cost-effective and easy to perform. However, in these countries, the tests are commonly used without any initial evaluation or monitoring of their performance despite high levels of HIV strain diversity and rapid evolution of the virus. In this study, the reliability and accuracy of HIV RDTs (Determine™, Multispot™, SD Bioline™) used in Mali, where HIV-1 and HIV-2 co-exist, were evaluated from August 2004 to November 2017. A total of 1303 samples from new HIV-suspect patients in Bamako were tested for HIV-1 and HIV-2 using the RDT Determine™, followed by ELISA and Western Blot (WB). The Determine™ test showed a robust diagnostic sensitivity of 98.7% [CI 95: 97.59-99.37] and a diagnostic specificity of 99.2% [CI 95: 98.22-99.67]. The Multispot™ assay showed a diagnostic sensitivity of 98.77% [CI 95: 97.59-99.37] and a diagnostic specificity of 99.2% [CI 95: 98.22-99.67]. The diagnostic sensitivity and specificity of SD Bioline™ HIV-1/2 were 100% [CI 95:72.25-100] and 88.89% [CI 95: 56.50- 98.71], respectively. These data indicate excellent performance for HIV RDTs in Mali and we recommend the use of Determine™ HIV-1/2 for HIV screening and Multispot™ for discriminating HIV-2 from HIV-1 infections.

Cost implications of HIV retesting for verification in Africa

INTRODUCTION

HIV misdiagnosis leads to severe individual and public health consequences. Retesting for verification of all HIV-positive cases prior to antiretroviral therapy initiation can reduce HIV misdiagnosis, yet this practice has not been not widely implemented.

METHODS

We evaluated and compared the cost of retesting for verification of HIV seropositivity (retesting) to the cost of antiretroviral treatment (ART) for misdiagnosed cases in the absence of retesting (no retesting), from the perspective of the health care system. We estimated the number of misdiagnosed cases based on a review of misdiagnosis rates, and the number of positives persons needing ART initiation by 2020. We presented the total and per person costs of retesting as compared to no retesting, over a ten-year horizon, across 50 countries in Africa grouped by income level. We conducted univariate sensitivity analysis on all model input parameters, and threshold analysis to evaluate the parameter values where the total costs of retesting and the costs no retesting are equivalent. Cost data were adjusted to 2017 United States Dollars.

RESULTS AND DISCUSSION

The estimated number of misdiagnoses, in the absence of retesting was 156,117, 52,720 and 29,884 for lower-income countries (LICs), lower-middle income countries (LMICs), and upper middle-income countries (UMICs), respectively, totaling 240,463 for Africa. Under the retesting scenario, costs per person initially diagnosed were: $40, $21, and $42, for LICs, LMICs, and UMICs, respectively. When retesting for verification is implemented, the savings in unnecessary ART were $125, $43, and $75 per person initially diagnosed, for LICs, LMICs, and UMICs, respectively. Over the ten-year horizon, the total costs under the retesting scenario, over all country income levels, was $475 million, and was $1.192 billion under the no retesting scenario, representing total estimated savings of $717 million in HIV treatment costs averted.

CONCLUSIONS

Results show that to reduce HIV misdiagnosis, countries in Africa should implement the WHO's recommendation of retesting for verification prior to ART initiation, as part of a comprehensive quality assurance program for HIV testing services.

Differences among diagnostic testing algorithms in the time from HIV diagnosis to care

BACKGROUND

The association between the type of diagnostic testing algorithm for HIV infection and the time from diagnosis to care has not been fully evaluated. Here we extend an earlier analysis of this association by controlling for patient and diagnosing facility characteristics.

STUDY DESIGN

Descriptive analysis of HIV infection diagnoses during 2016 reported to the National HIV Surveillance System through December 2017. Algorithm type: traditional = initial HIV antibody immunoassay followed by a Western blot or immunofluorescence antibody test; recommended = initial HIV antigen/antibody immunoassay followed by HIV-1/2 type-differentiating antibody test; rapid = two CLIA-waived rapid tests on the same date.

RESULTS

In multivariate analyses controlling for patient and diagnosing facility characteristics, persons whose infection was diagnosed using the rapid algorithm were more likely to be linked to care within 30 days than those whose infection was diagnosed using the other testing algorithms (p < 0.01). The median time to link to care during a 30-day follow-up was 9.0 days (95% CI 8.0-12.0) after the rapid algorithm, 17.0 days (95% CI 17.0-18.0) after the recommended algorithm, and 23.0 days (95% CI 22.0-25.0) after the traditional algorithm.

CONCLUSIONS

The time from HIV diagnosis to care varied with the type of testing algorithm. The median time to care was shortest for the rapid algorithm, longest for the traditional algorithm, and intermediate for the recommended algorithm. These results demonstrate the importance of choosing an algorithm with a short time between initial specimen collection and report of the final result to the patient.

Diagnostic Performance of MALDI-TOF MS Compared to Conventional Microbiological Cultures in Patients with Suspected Endophthalmitis

Purpose: To evaluate the performance and speed of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) when identifying the pathogenic microorganism of endophthalmitis compared to conventional microbiological culturing.Methods: Forty-four patients with suspected endophthalmitis who had undergone vitrectomy were enrolled. Vitreous specimen was analyzed using either conventional culturing or MALDI-TOF MS.Results: The identification rates of the conventional microbiological culture and MALDI-TOF MS were 45.5% (20/44) and 65.9% (29/44), respectively (Kappa value 0.787, P < 0.000). The mean detection times by the standard culturing method and MALDI-TOF MS were 5.39 ± 0.56d and 3.17 ± 0.40d (P < 0.001). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MALDI-TOF MS were 70.59%, 54.17%, 80.00%, and 86.67%, respectively. Polymicrobial endophthalmitis was identified in 6.82% of the patients (3/44) using conventional microbiological culturing. However, MALDI-TOF MS failed to identify any polymicrobial infection.Conclusions: With a higher sensitivity, acceptable specificity and a shorter detection time, MALDI-TOF MS was an efficient technique for the rapid identification of a pathogenic microorganism in endophthalmitis.

HIV Testing After a First Positive Rapid Diagnostic Test: A Role for Nucleic Acid Testing?

We developed an open-access, Excel-based model simulating currently recommended and alternative algorithms for adult HIV testing as a preliminary investigation of trade-offs between accuracy and costs. Despite higher costs, simpler HIV testing algorithms incorporating point of care nucleic acid testing may improve outcomes and thus merit additional research and field testing.

The role of trehalose in the global spread of epidemic Clostridium difficile

In a recent study, we reported on two distantly related, epidemic lineages of Clostridium difficile that have acquired independent mechanisms to metabolize low concentrations of trehalose. Here we provide further comment and evidence that a third epidemic lineage common in Asia and Europe, ribotype 017, has evolved this ability.