Performance of the SAMBA I and II HIV-1 Semi-Q Tests for viral load monitoring at the point-of-care

Assessment of the performance of the plasma separation card for HIV-1 viral load monitoring in South Africa

Scaling up of newer innovations that address the limitations of the dried blood spot and the logistics of plasma monitoring is needed. We employed a multi-site, cross-sectional assessment of the plasma separation card (PSC) on blood specimens collected from all consenting adults, assenting young and pediatric patients living with HIV from 10 primary healthcare clinics in South Africa. Venous blood for EDTA-plasma samples was collected and analyzed according to the standard of care assay, while collected capillary blood for the PSC samples was analyzed using the Roche COBAS AmpliPrep/Cobas TaqMan (CAP/CTM) HIV-1 Test at the National Reference laboratories. McNemar tests assessed the differences in concordance between the centrifuged plasma and dried plasma spots. The usability of PSC by blood spotting, PSC preparation, and pre-analytical work was assessed by collecting seven-point Likert-scale data from healthcare and laboratory workers. We enrolled 538 patients, mostly adults [n = 515, 95.7% (95% CI: 93.7%-97.1%)] and females [n = 322, 64.2% (95% CI: 60.0%-68.1%)]. Overall, 536 paired samples were collected using both PSC- and EDTA-plasma diagnostics, and 502 paired PSC- and EDTA-plasma samples assessed. Concordance between the paired samples was obtained for 446 samples. Analysis of these 446 paired samples at 1,000 copies per milliliter threshold yielded an overall sensitivity of 87.5% [95% CI: 73.2%-95.8%] and specificity of 99.3% [95% CI: 97.9%-99.8%]. Laboratory staff reported technical difficulties in most tasks. The usability of the PSC by healthcare workers was favorable. For policymakers to consider PSC scale-up for viral load monitoring, technical challenges around using PSC at the clinic and laboratory level need to be addressed.

IMPORTANCE

Findings from this manuscript emphasize the reliability of the plasma separation card (PSC), a novel diagnostic method that can be implemented in healthcare facilities in resource-constrained settings. The agreement of the PSC with the standard of care EDTA plasma for viral load monitoring is high. Since the findings showed that these tests were highly specific, we recommend a scale-up of PSC in South Africa for diagnosis of treatment failure.

Performances of Dried Blood Spots and Point-of-Care Devices to Identify Virological Failure in HIV-Infected Patients: A Systematic Review and Meta-Analysis

To broaden access to HIV viral load monitoring (VLM), the use of blood samples from dried blood spots (DBS) or point-of-care (POC) devices, could be of great help in settings where plasma is not easily accessible. The variety of assays available makes the choice complex. This systematic review and meta-analysis aims to estimate the sensitivity and specificity of DBS and POC devices to identify patients in virological failure using World Health Organization (WHO) recommendations (viral load ≥1000 copies/mL), compared with plasma, for the assays currently available. Four databases were searched for articles, and two reviewers independently identified articles reporting sensitivity and specificity of DBS and/or POC to identify patients in virological failure. We excluded articles that used other thresholds as well as articles with a total number of participants below 50 to avoid reporting bias. Heterogeneity and factors associated with assays' performances were assessed by I² statistics and metaregression. The protocol of this review follows the PRISMA guidelines. Out of 941 articles, 47 were included: 32 DBS evaluations and 16 POC evaluations. Overall, when using DBS, the Abbott RT HIV-1, Roche CAP-CTM, NucliSENS BioMerieux and Aptima assays presented sensitivity and specificity exceeding 85%, but reported results were highly heterogeneous. Factors associated with better performances were high volume of blood and the use of the same assay for DBS and plasma VLM. Regarding the POC devices, SAMBA I, SAMBA II, and GeneXpert devices presented high sensitivity and specificity exceeding 90%, with less heterogeneity. DBS is suitable VLM, but performances can vary greatly depending on the protocols, and should be performed in trained centers. POC is suitable for VLM with less risk of heterogeneity but is more intensive in costs and logistics.

Sensitive and Quantitative Point-of-Care HIV Viral Load Quantification from Blood Using a Power-Free Plasma Separation and Portable Magnetofluidic Polymerase Chain Reaction Instrument

Point-of-care (POC) HIV viral load (VL) tests are needed to enhance access to HIV VL testing in low- and middle-income countries (LMICs) and to enable HIV VL self-testing at home, which in turn have the potential to enhance the global management of the disease. While methods based on real-time reverse transcription-polymerase chain reaction (RT-PCR) are highly sensitive and quantitatively accurate, they often require bulky and expensive instruments, making applications at the POC challenging. On the other hand, although methods based on isothermal amplification techniques could be performed using low-cost instruments, they have shown limited quantitative accuracies, i.e., being only semiquantitative. Herein, we present a sensitive and quantitative POC HIV VL quantification method from blood that can be performed using a small power-free three-dimensional-printed plasma separation device and a portable, low-cost magnetofluidic real-time RT-PCR instrument. The plasma separation device, which is composed of a plasma separation membrane and an absorbent material, demonstrated 96% plasma separation efficiency per 100 μL of whole blood. The plasma solution was then processed in a magnetofluidic cartridge for automated HIV RNA extraction and quantification using the portable instrument, which completed 50 cycles of PCR in 15 min. Using the method, we achieved a limit of detection of 500 HIV RNA copies/mL, which is below the World Health Organization's virological failure threshold, and a good quantitative accuracy. The method has the potential for sensitive and quantitative HIV VL testing at the POC and at home self-testing.

Evaluation of SAMBA II: A Qualitative and Semiquantitative HIV Point-of-Care Nucleic Acid Test

BACKGROUND

Point-of-care (POC) nucleic acid tests (NATs) have potential to diagnose acute HIV infection and monitor persons taking pre-exposure prophylaxis or antiretroviral therapy (ART). POC NATs have not yet been evaluated in the US.

METHODS

From June 2018-March 2019, we conducted a cross-sectional evaluation of the Simple Amplification-Based Assay version II (SAMBA II) POC NAT. People with HIV (PWH) and persons testing for HIV were tested with the SAMBA II qualitative (Qual) whole blood (WB) test. From April-September 2019, the Qual test was used on persons who were ART-naive, and SAMBA II Semi-quantitative (Semi-Q) WB was used with ART-experienced PWH. Both were performed on unprocessed venipuncture (VP) and, when indicated by protocol, fingerstick (FS) WB and plasma. SAMBA results were compared with Abbott RealTime HIV-1 polymerase chain reaction results on plasma. We calculated sensitivity, specificity, and concordance between tests.

RESULTS

SAMBA was used in 330 visits among 280 participants: 202 (61.2%) visits from PWH, and 128 (38.8%) from HIV-negative persons. Qual test sensitivity with ART-naive participants was 91.4% [32/35, 95% confidence interval (CI): 77.6% to 97.0%] using VP WB and 100% (27/27, 95% CI: 87.5% to 100%) using FS WB. Specificity was 100% using both specimen types. Concordance between the gold standard and Semi-Q at 1000 copies/mL among PWH on ART was 97.7% (86/88, 95% CI: 92.1% to 99.4%) and 100% (30/30, 95% CI: 88.7% to 100%) using VP and FS WB, respectively.

CONCLUSIONS

The SAMBA II POC NATs showed high sensitivity, specificity, and concordance with the gold standard assay, indicating its potential use in diagnostics and monitoring. Future work will evaluate POC NAT implementation in the US.

Point-of-care viral load tests to detect high HIV viral load in people living with HIV/AIDS attending health facilities

BACKGROUND

Viral load (VL) testing in people living with HIV (PLHIV) helps to monitor antiretroviral therapy (ART). VL is still largely tested using central laboratory-based platforms, which have long test turnaround times and involve sophisticated equipment. VL tests with point-of-care (POC) platforms capable of being used near the patient are potentially easy to use, give quick results, are cost-effective, and could replace central or reference VL testing platforms.

OBJECTIVES

To estimate the diagnostic accuracy of POC tests to detect high viral load levels in PLHIV attending healthcare facilities.

SEARCH METHODS

We searched eight electronic databases using standard, extensive Cochrane search methods, and did not use any language, document type, or publication status limitations. We also searched the reference lists of included studies and relevant systematic reviews, and consulted an expert in the field from the World Health Organization (WHO) HIV Department for potentially relevant studies. The latest search was 23 November 2020.

SELECTION CRITERIA

We included any primary study that compared the results of a VL test with a POC platform to that of a central laboratory-based reference test to detect high viral load in PLHIV on HIV/AIDS care or follow-up. We included all forms of POC tests for VL as defined by study authors, regardless of the healthcare facility in which the test was conducted. We excluded diagnostic case-control studies with healthy controls and studies that did not provide sufficient data to create the 2 × 2 tables to calculate sensitivity and specificity. We did not limit our study inclusion to age, gender, or geographical setting.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles, abstracts, and full texts of the search results to identify eligible articles. They also independently extracted data using a standardized data extraction form and conducted risk of bias assessment using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Using participants as the unit of analysis, we fitted simplified univariable models for sensitivity and specificity separately, employing a random-effects model to estimate the summary sensitivity and specificity at the current and commonly reported World Health Organization (WHO) threshold (≥ 1000 copies/mL). The bivariate models did not converge to give a model estimate.

MAIN RESULTS

We identified 18 studies (24 evaluations, 10,034 participants) defining high viral loads at main thresholds ≥ 1000 copies/mL (n = 20), ≥ 5000 copies/mL (n = 1), and ≥ 40 copies/mL (n = 3). All evaluations were done on samples from PLHIV retrieved from routine HIV/AIDS care centres or health facilities. For clinical applicability, we included 14 studies (20 evaluations, 8659 participants) assessing high viral load at the clinical threshold of ≥ 1000 copies/mL in the meta-analyses. Of these, sub-Saharan Africa, Europe, and Asia contributed 16, three, and one evaluation respectively. All included participants were on ART in only nine evaluations; in the other 11 evaluations the proportion of participants on ART was either partial or not clearly stated. Thirteen evaluations included adults only (n = 13), five mixed populations of adults and children, whilst in the remaining two the age of included populations was not clearly stated. The majority of evaluations included commercially available tests (n = 18). Ten evaluations were POC VL tests conducted near the patient in a peripheral or onsite laboratory, whilst the other 10 were evaluations of POC VL tests in a central or reference laboratory setting. The test types evaluated as POC VL tests included Xpert HIV-1 Viral Load test (n = 8), SAMBA HIV-1 Semi-Q Test (n = 9), Alere Q NAT prototype assay for HIV-1 (n = 2) and m-PIMA HIV-1/2 Viral Load test (n = 1). The majority of evaluations (n = 17) used plasma samples, whilst the rest (n = 3) utilized whole blood samples. Pooled sensitivity (95% confidence interval (CI)) of POC VL at a threshold of ≥ 1000 copies/mL was 96.6% (94.8 to 97.8) (20 evaluations, 2522 participants), and pooled specificity (95% CI) was 95.7% (90.8 to 98.0) (20 evaluations, 6137 participants). Median prevalence for high viral load (≥ 1000 copies/mL) (n = 20) was 33.4% (range 6.9% to 88.5%). Limitations The risk of bias was mostly assessed as unclear across the four domains due to incomplete reporting.

AUTHORS' CONCLUSIONS

We found POC VL to have high sensitivity and high specificity for the diagnosis of high HIV viral load in PLHIV attending healthcare facilities at a clinical threshold of ≥ 1000 copies/mL.

Study To Evaluate the Performance of a Point-of-Care Whole-Blood HIV Viral Load Test (SAMBA II HIV-1 Semi-Q Whole Blood)

Remote areas of many low and middle income (LMI) countries have poor access to HIV viral load (HIV VL) testing. The SAMBA II (simple amplification-based assay) Semi-Q whole-blood test (Diagnostics for the Real World [DRW], Cambridge, UK) is a point-of-care assay, which uses leucodepletion technology to allow whole-blood testing in remote settings. A total of 1,540 consecutive HIV-positive clinic patients in Cameroon (250), United Kingdom (633), Ukraine (412), and Zimbabwe (245) donated venous blood (all countries) and finger prick blood (all except UK) for testing on SAMBA II. SAMBA II results were compared with simultaneous plasma results on the Abbott RealTime HIV-1 (Abbott Molecular, Des Plaines, IL) viral load assay and interpreted as either <1,000 RNA copies/ml or ≥1,000 RNA copies/ml. For 1,528 venous whole-blood samples tested on SAMBA II, overall percent agreement with the reference test at a cutoff HIV VL of ≥1,000 copies/ml was 96.9% (1,480/1,528; 95% confidence interval [CI], 95.9% to 97.7%), negative percent agreement was 97.7% (1,259/1,289; 95% CI, 96.7% to 98.4%), and positive percent agreement was 92.5% (221/239; 95% CI, 88.4% to 95.5%). For 854 finger prick samples, there was 95.0% (811/854; 95% CI, 93.3% to 96.3%) overall percent agreement, 98.0% (625/638; 95% CI, 96.5% to 98.9%) negative percent agreement, and 86.1% (186/216; 95% CI, 80.8% to 90.4%) positive percent agreement. These rose to 93.5% (82.1% to 98.6%), 97.6% (95.6% to 98.8%), and 95.6% (93.3% to 97.3%) after exclusion of aberrant results from the Ukraine center. These results show a high level of agreement between SAMBA-II and a laboratory-based assay. SAMBA-II has a performance that is suitable to use as a VL point-of-care assay in remote settings.

Viral load care of HIV-1 infected children and adolescents: A longitudinal study in rural Zimbabwe

INTRODUCTION

Maintaining virologic suppression of children and adolescents on ART in rural communities in sub-Saharan Africa is challenging. We explored switching drug regimens to protease inhibitor (PI) based treatment and reducing nevirapine and zidovudine use in a differentiated community service delivery model in rural Zimbabwe.

METHODS

From 2016 through 2018, we followed 306 children and adolescents on ART in Hurungwe, Zimbabwe at Chidamoyo Christian Hospital, which provides compact ART regimens at 8 dispersed rural community outreach sites. Viral load testing was performed (2016) by Roche and at follow-up (2018) by a point of care viral load assay. Virologic failure was defined as viral load ≥1,000 copies/ml. A logistic regression model which included demographics, treatment regimens and caregiver's characteristics was used to assess risks for virologic failure and loss to follow-up (LTFU).

RESULTS

At baseline in 2016, 296 of 306 children and adolescents (97%) were on first-line ART, and only 10 were receiving a PI-based regimen. The median age was 12 years (IQR 8-15) and 55% were female. Two hundred and nine (68%) had viral load suppression (<1,000 copies/ml) and 97(32%) were unsuppressed (viral load ≥1000). At follow-up in 2018, 42/306 (14%) were either transferred 23 (7%) or LTFU 17 (6%) and 2 had died. In 2018, of the 264 retained in care, 107/264 (41%), had been switched to second-line, ritonavir-boosted PI with abacavir as a new nucleotide analog reverse transcriptase inhibitor (NRTI). Overall viral load suppression increased from 68% in 2016 to 81% in 2018 (P<0.001).

CONCLUSION

Viral load testing, and switching to second-line, ritonavir-boosted PI with abacavir significantly increased virologic suppression among HIV-infected children and adolescents in rural Zimbabwe.

Performance Evaluation of the SAMBA II SARS-CoV-2 Test for Point-of-Care Detection of SARS-CoV-2

Nucleic acid amplification for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in respiratory samples is the standard method for diagnosis. The majority of this testing is centralized and therefore has turnaround times of several days. Point-of-care (POC) testing with rapid turnaround times would allow more effective triage in settings where patient management and infection control decisions need to be made rapidly. The inclusivity and specificity of the Simple AMplification-Based Assay (SAMBA) II SARS-CoV-2 test were determined by both in silico analyses of the primers and probes and wet testing. The SAMBA II SARS-CoV-2 test was evaluated for performance characteristics. Clinical performance was evaluated in residual combined throat/nose swabs and compared to that of the Public Health England real-time PCR assay targeting the RdRp gene. The SAMBA II SARS-CoV-2 test has an analytical sensitivity of 250 copies/ml for detecting two regions of the genome (open reading frame 1ab [ORF1ab] and nucleocapsid protein [N]). The clinical performance was evaluated in 172 residual combined nose/throat swabs provided by the Clinical Microbiology and Public Health Laboratory, Addenbrooke's Hospital, Cambridge (CMPHL), which showed an estimated positive percent agreement of 98.9% (95% confidence interval [CI], 93.83 to 99.97) and negative percent agreement of 96.4% (95% CI, 89.92 to 99.26) compared to testing by the CMPHL. The data show that the SAMBA II SARS-CoV-2 test performs equivalently to the centralized testing methods, but with a shorter turnaround time of 86 to 101 min. Point-of-care tests such as SAMBA should enable rapid patient management and effective implementation of infection control measures.

Implementation and operational feasibility of SAMBA I HIV-1 semi-quantitative viral load testing at the point-of-care in rural settings in Malawi and Uganda

OBJECTIVE

We monitored a large-scale implementation of the Simple Amplification-Based Assay semi-quantitative viral load test for HIV-1 version I (SAMBA I Viral Load = SAMBA I VL) within Médecins Sans Frontières' HIV programmes in Malawi and Uganda, to assess its performance and operational feasibility.

METHODS

Descriptive analysis of routine programme data between August 2013 and December 2016. The dataset included samples collected for VL monitoring and tested using SAMBA I VL in five HIV clinics in Malawi (four peripheral health centres and one district hospital), and one HIV clinic in a regional referral hospital in Uganda. SAMBA I VL was used for VL testing in patients who had been receiving ART for between 6 months and ten years, to determine whether plasma VL was above or below 1000 copies/mL of HIV-1, reflecting ART failure or efficacy. Randomly selected samples were quantified with commercial VL assays. SAMBA I instruments and test performance, site throughput, and delays in communicating results to clinicians and patients were monitored.

RESULTS

Between August 2013 and December 2016 a total of 60 889 patient samples were analysed with SAMBA I VL. Overall, 0.23% of initial SAMBA I VL results were invalid; this was reduced to 0.04% after repeating the test once. Global test failure, including instrument failure, was 1.34%. Concordance with reference quantitative testing of VL was 2620/2727, 96.0% (1338/1382, 96.8% in Malawi; 1282/1345, 95.3% in Uganda). For Chiradzulu peripheral health centres and Arua Hospital HIV clinic, where testing was performed on-site, same-day results were communicated to clinicians for between 91% and 97% of samples. Same-day clinical review was obtained for 84.7% across the whole set of samples tested.

CONCLUSIONS

SAMBA I VL testing is feasible for monitoring cohorts of 1000 to 5000 ART-experienced patients. Same-day results can be used to inform rapid clinical decision-making at rural and remote health facilities, potentially reducing time available for development of resistance and conceivably helping to reduce morbidity and mortality.

Optimizing viral load suppression in Kenyan children on antiretroviral therapy (Opt4Kids)

Background

As many as 40% of the 1 million children living with HIV (CLHIV) receiving antiretroviral treatment (ART) in resource limited settings have not achieved viral suppression (VS). Kenya has a large burden of pediatric HIV with nearly 140,000 CLHIV. Feasible, scalable, and cost-effective approaches to ensure VS in CLHIV are urgently needed. The goal of this study is to determine the feasibility and impact of point-of-care (POC) viral load (VL) and targeted drug resistance mutation (DRM) testing to improve VS in children on ART in Kenya.

Methods

We are conducting a randomized controlled study to evaluate the use of POC VL and targeted DRM testing among 704 children aged 1-14 years on ART at health facilities in western Kenya. Children are randomized 1:1 to intervention (higher frequency POC VL and targeted DRM testing) vs. control (standard-of-care) arms and followed for 12 months. Our primary outcome is VS (VL < 1000 copies/mL) 12 months after enrollment by study arm. Secondary outcomes include time to VS and the impact of targeted DRM testing on VS. In addition, key informant interviews with patients and providers will generate an understanding of how the POC VL intervention functions. Finally, we will model the cost-effectiveness of POC VL combined with targeted DRM testing.

Discussion

This study will provide critical information on the impact of POC VL and DRM testing on VS among CLHIV on ART in a resource-limited setting and directly address the need to find approaches that maximize VS among children on ART.

Trials registration

NCT03820323.

An open-source molecular diagnostic platform approach for outbreak and epidemic preparedness

Background

Diagnostic development for outbreak pathogens has typically followed a disease-specific reactive rather than proactive response. Given the diversity of outbreak pathogens, particularly those prioritised by the World Health Organization Research and Development Blueprint, a more flexible and proactive approach to epidemic preparedness is needed to expand access to critical molecular diagnostic tests in peripheral and resource-constrained deployment settings.

Objective

New and more sustainable directives are needed to spur the development of high-quality products, particularly for epidemics more often found in low- and middle-income countries. To leverage and de-risk the development process, we present the benefits and challenges of an open-source business model for co-development of molecular diagnostic tests for decentralised settings.

Methods

We identify key outbreak pathogens that are available only for testing in high infrastructure laboratories and compare in-country installed base platforms that could be leveraged for menu expansion. Key strengths and challenges for development are highlighted for both platform and assay developers, with discussion of how to leverage and de-risk the process through an open-source development model.

Results

Depending on the specific partner strengths, options for partnership roles are presented. The proposed open-source business model addresses the particular challenges in the detection of outbreak- and epidemic-prone pathogens in low- and middle-income countries, reduces development and deployment risks to support outbreak response, strengthens diagnostic capacity and creates a viable market for product developers.

Conclusion

We hope this model for a collaborative and open-source approach for molecular diagnostics serves to encourage stakeholders to consider co-development partnerships to improve outbreak preparedness and epidemic/pandemic response.

Point of Care Nucleic Acid Testing for SARS-CoV-2 in Hospitalized Patients: A Clinical Validation Trial and Implementation Study

There is an urgent need for rapid SARS-CoV-2 testing in hospitals to limit nosocomial spread. We report an evaluation of point of care (POC) nucleic acid amplification testing (NAAT) in 149 participants with parallel combined nasal and throat swabbing for POC versus standard lab RT-PCR testing. Median time to result is 2.6 (IQR 2.3-4.8) versus 26.4 h (IQR 21.4-31.4, p < 0.001), with 32 (21.5%) positive and 117 (78.5%) negative. Cohen's κ correlation between tests is 0.96 (95% CI 0.91-1.00). When comparing nearly 1,000 tests pre- and post-implementation, the median time to definitive bed placement from admission is 23.4 (8.6-41.9) versus 17.1 h (9.0-28.8), p = 0.02. Mean length of stay on COVID-19 "holding" wards is 58.5 versus 29.9 h (p < 0.001). POC testing increases isolation room availability, avoids bed closures, allows discharge to care homes, and expedites access to hospital procedures. POC testing could mitigate the impact of COVID-19 on hospital systems.

Point-of-care viral load monitoring: outcomes from a decentralized HIV programme in Malawi

Introduction

Routinely monitoring the HIV viral load (VL) of people living with HIV (PLHIV) on anti‐retroviral therapy (ART) facilitates intensive adherence counselling and faster ART regimen switch when treatment failure is indicated. Yet standard VL‐testing in centralized laboratories can be time‐intensive and logistically difficult in low‐resource settings. This paper evaluates the outcomes of the first four years of routine VL‐monitoring using Point‐of‐Care technology, implemented by Médecins Sans Frontières (MSF) in rural clinics in Malawi.

Methods

We conducted a retrospective cohort analysis of patients eligible for routine VL‐ testing between 2013 and 2017 in four decentralized ART‐clinics and the district hospital in Chiradzulu, Malawi. We assessed VL‐testing coverage and the treatment failure cascade (from suspected failure (first VL>1000 copies/mL) to VL suppression post regimen switch). We used descriptive statistics and multivariate logistic regression to assess factors associated with suspected failure.

Results and Discussion

Among 21,400 eligible patients, VL‐testing coverage was 85% and VL suppression was found in 89% of those tested. In the decentralized clinics, 88% of test results were reviewed on the same day as blood collection, whereas in the district hospital the median turnaround‐time for results was 85 days. Among first‐line ART patients with suspected failure (N = 1544), 30% suppressed (VL<1000 copies/mL), 35% were treatment failures (confirmed by subsequent VL‐testing) and 35% had incomplete VL follow‐up. Among treatment failures, 80% (N = 540) were switched to a second‐line regimen, with a higher switching rate in the decentralized clinics than in the district hospital (86% vs. 67%, p < 0.01) and a shorter median time‐to‐switch (6.8 months vs. 9.7 months, p < 0.01). Similarly, the post‐switch VL‐testing rate was markedly higher in the decentralized clinics (61% vs. 26%, p < 0.01). Overall, 79% of patients with a post‐switch VL‐test were suppressed.

Conclusions

Viral load testing at the point‐of‐care in Chiradzulu, Malawi achieved high coverage and good drug regimen switch rates among those identified as treatment failures. In decentralized clinics, same‐day test results and shorter time‐to‐switch illustrated the game‐changing potential of POC‐based VL‐testing. Nevertheless, gaps were identified along all steps of the failure cascade. Regular staff training, continuous monitoring and creating demand are essential to the success of routine VL‐testing.

Point-of-care HIV viral load testing combined with task shifting to improve treatment outcomes (STREAM): findings from an open-label, non-inferiority, randomised controlled trial

BACKGROUND

Monitoring HIV treatment with laboratory testing introduces delays for providing appropriate care in resource-limited settings. The aim of our study was to determine whether point-of-care HIV viral load testing with task shifting changed treatment and care outcomes for adults on antiretroviral therapy (ART) when compared with standard laboratory viral load testing.

METHODS

We did an open-label, non-inferiority, randomised controlled trial in a public clinic in Durban, South Africa. We enrolled HIV-positive adults (aged ≥18 years) who presented for their first routine HIV viral load test 6 months after ART initiation. Individuals were randomly assigned by a random number allocation sequence to receive either point-of-care viral load testing at enrolment and after 6 months with task shifting to enrolled nurses (intervention group), or laboratory viral load testing (standard-of-care group). The primary outcome was combined viral suppression (<200 copies per mL) and retention at 12 months after enrolment. A non-inferiority margin of 10% was used. Analysis was done by intention to treat. This study was registered with ClinicalTrials.gov, NCT03066128.

FINDINGS

Between Feb 24, 2017, and Aug 23, 2017, we screened 657 participants, and 390 were enrolled and randomly assigned to either the intervention group (n=195) or standard-of-care group (n=195). 175 (90%) individuals in the intervention group and 148 (76%) individuals in the standard-of-care group had the primary outcome of retention with viral suppression, a difference of 13·9% (95% CI 6·4-21·2; p<0·00040). 182 participants (93%) in the intervention group had viral suppression compared with 162 (83%) in the standard-of-care group (difference 10·3%, 3·9-16·8; p=0·0025); 180 (92%) and 162 (85%) were retained in care (7·7%, 1·3-14·2; p=0·026). There were no adverse events related to point-of-care HIV viral load testing or task shifting.

INTERPRETATION

Point-of-care viral load testing combined with task shifting significantly improved viral suppression and retention in HIV care. Point-of-care testing can simplify treatment and improve outcomes for HIV-positive adults receiving ART in resource-limited settings.

FUNDING

National Institute of Allergy and Infectious Diseases.

Performance and usability of mPIMA™ HIV 1/2 viral load test in point of care settings in Kenya

BACKGROUND

HIV viral load testing is the standard of care for monitoring antiretroviral therapy. In resource-limited settings such as Kenya, access to HIV viral load monitoring is suboptimal due to reliance on centralized laboratory based in vitro diagnostics. Point of care technologies have the potential to improve access and reduce test to result turnaround time.

OBJECTIVE

To determine the performance and usability of the mPIMA™ HIV-1/2 Viral Load (VL) test in point of care settings in Kenya.

METHOD

This was a cross-sectional study conducted amongst 568 HIV positive adults recruited from selected health facilities in Western Kenya between June and November 2018. Five hundred and sixty-six plasma samples (566) were tested successfully on Abbott™ RealTime HIV-1 quantitative test (reference assay) and mPIMA™ HIV-1/2 Viral Load test to determine diagnostic accuracy. Usability data was collected through simple structured questionnaires. Statistical analysis was done using Stata/MP Version 14 for Mac OSX. Concordance and misclassification values were calculated at the clinical cut-off of 1000 copies/ml.

RESULTS

The positive, negative and overall agreement of the mPIMA™ HIV-1/2 V L test were 95.45% (95% CI 89.49-98.11%), 95.96% (95% CI 93.66-97.44%) and 95.86% respectively. All users (7/7, 100%) reported that the machine was easy to use and that the results interpretation and workflow were simple. The test to result turnaround time was 69 min. All clinicians (4/4, 100%) felt that a Point of care test would fit easily within their workflow and would facilitate decision-making. There were 44 (7.77%) errors in 566 tests; 38 (6.71%) were user related and four (4, 0.71%) were software related.

CONCLUSION

The mPIMA™ HIV-1/2 V L test can be used interchangeably with reference assays for HIV viral load monitoring. At the point of care, mPIMA™'s simple workflow, ease of use and short test to result turnaround time have the potential to improve access to HIV viral load monitoring.

Advances in diagnostic microfluidics

Microfluidics is an emerging field in diagnostics that allows for extremely precise fluid control and manipulation, enabling rapid and high-throughput sample processing in integrated micro-scale medical systems. These platforms are well-suited for both standard clinical settings and point-of-care applications. The unique features of microfluidics-based platforms make them attractive for early disease diagnosis and real-time monitoring of the disease and therapeutic efficacy. In this chapter, we will first provide a background on microfluidic fundamentals, microfluidic fabrication technologies, microfluidic reactors, and microfluidic total-analysis-systems. Next, we will move into a discussion on the clinical applications of existing and emerging microfluidic platforms for blood analysis, and for diagnosis and monitoring of cancer and infectious disease. Together, this chapter should elucidate the potential that microfluidic systems have in the development of effective diagnostic technologies through a review of existing technologies and promising directions.

Systematic review of the performance and clinical utility of point of care HIV-1 RNA testing for diagnosis and care

BACKGROUND

Point of-care (POC) HIV-1 RNA tests which are accurate and easy to use with limited infrastructure are needed in resource-limited settings (RLS). We systematically reviewed evidence of POC test performance compared to laboratory-based HIV-1 RNA assays and the potential utility of these tests for diagnosis and care in RLS.

METHODS

Studies published up to July 2018 were identified by a search of PUBMED, EMBASE, Web of Science, CINAHL and Cochrane Central Register of Controlled Trials. Studies evaluating the use of POC HIV-1 RNA testing for early infant diagnosis (EID), acute HIV infection (AHI) diagnosis, or viral load monitoring (VL), compared to centralized testing, were included. Separate search strategies were used for each testing objective.

RESULTS

197 abstracts were screened and 34 full-text articles were assessed, of which 32 met inclusion criteria. Thirty studies evaluated performance and diagnostic accuracy of POC tests compared to standard reference tests. Two of the thirty and two additional studies with no comparative testing reported on clinical utility of POC results. Five different POC tests (Cepheid GeneXpert HIV-1 Quantitative and Qualitative assays, Alere q HIV-1/2 Detect, SAMBA, Liat HIV Quant and Aptima HIV-1 Quant) were used in 21 studies of VL, 11 of EID and 2 of AHI. POC tests were easy to use, had rapid turnaround times, and comparable accuracy and precision to reference technologies. Sensitivity and specificity were high for EID and AHI but lower for VL. For VL, lower sensitivity was reported for whole blood and dried blood spots compared to plasma samples. Reported error rates for Cepheid GeneXpert Qual (2.0%-5.0%), GeneXpert Quant (2.5%-17.0%) and Alere q HIV-1/2 Detect (3.1%-11.0%) were higher than in WHO prequalification reports. Most errors resolved with retesting; however, inadequate sample volumes often precluded repeat testing. Only two studies used POC results for clinical management, one for EID and another for VL. POC EID resulted in shorter time-to-result, rapid ART initiation, and better retention in care compared to centralised testing.

CONCLUSIONS

Performance of POC HIV-1 RNA tests is comparable to reference assays, and have potential to improve patient outcomes. Additional studies on implementation in limited-resources settings are needed.

Point-of-Care HIV Viral Load Testing: an Essential Tool for a Sustainable Global HIV/AIDS Response

The global public health community has set ambitious treatment targets to end the HIV/AIDS pandemic. With the notable absence of a cure, the goal of HIV treatment is to achieve sustained suppression of an HIV viral load, which allows for immunological recovery and reduces the risk of onward HIV transmission. Monitoring HIV viral load in people living with HIV is therefore central to maintaining effective individual antiretroviral therapy as well as monitoring progress toward achieving population targets for viral suppression. The capacity for laboratory-based HIV viral load testing has increased rapidly in low- and middle-income countries, but implementation of universal viral load monitoring is still hindered by several barriers and delays. New devices for point-of-care HIV viral load testing may be used near patients to improve HIV management by reducing the turnaround time for clinical test results. The implementation of near-patient testing using these new and emerging technologies may be an essential tool for ensuring a sustainable response that will ultimately enable an end to the HIV/AIDS pandemic. In this report, we review the current and emerging technology, the evidence for decentralized viral load monitoring by non-laboratory health care workers, and the additional considerations for expanding point-of-care HIV viral load testing.

HIV-1 drug resistance testing at second-line regimen failure in Arua, Uganda: avoiding unnecessary switch to an empiric third-line

OBJECTIVES

The number of patients on second-line antiretroviral therapy is growing, but data on HIV drug resistance patterns at failure in resource-constrained settings are scarce. We aimed to describe drug resistance and investigate the factors associated with extensive resistance to nucleoside/nucleotide reverse transcriptase inhibitors (NRTI), in patients failing second-line therapy in the HIV outpatient clinic at Arua Regional Referral Hospital, Uganda.

METHODS

We included patients who failed on second-line therapy (two consecutive viral loads ≥1000 copies/mm³ by SAMBA-1 point-of-care test) and who had a drug resistance test performed between September 2014 and March 2017. Logistic regression was used to investigate factors associated with NRTI genotypic sensitivity score (GSS) ≤1.

RESULTS

Seventy-eight patients were included: 42% female, median age 31 years and median time of 29 months on second-line therapy. Among 70 cases with drug resistance test results, predominant subtypes were A (47%) and D (40%); 18.5% had ≥1 major protease inhibitor mutation; 82.8% had ≥1 NRTI mutation and 38.5% had extensive NRTI resistance (NRTI GSS ≤1). A nadir CD4 count ≤100/ml was associated with NRTI GSS ≤1 (OR 4.2, 95% CI [1.3-15.1]). Thirty (42.8%) patients were switched to third-line therapy, composed of integrase inhibitor and protease inhibitor (60% darunavir/r) +/- NRTI. A follow-up viral load was available for 19 third-line patients at 12 months: 84.2% were undetectable.

CONCLUSIONS

Our study highlights the need for access to drug resistance tests to avoid unnecessary switches to third-line therapy, but also for access to third-line drugs, in particular integrase inhibitors. Low nadir CD4 count might be an indicator of third-line drug requirement for patients failing second-line therapy.

Diagnostic tests for Crimean-Congo haemorrhagic fever: a widespread tickborne disease

Crimean-Congo haemorrhagic fever (CCHF) is a widespread tickborne disease that circulates in wild and domestic animal hosts, and causes severe and often fatal haemorrhagic fever in infected humans. Due to the lack of treatment options or vaccines, and a high fatality rate, CCHF virus (CCHFV) is considered a high-priority pathogen according to the WHO R&D Blueprint. Several commercial reverse transcriptase PCR (RT-PCR) and serological diagnostic assays for CCHFV are already available, including febrile agent panels to distinguish CCHFV from other viral haemorrhagic fever agents; however, the majority of international laboratories use inhouse assays. As CCHFV has numerous amplifying animal hosts, a cross-sectoral 'One Health' approach to outbreak prevention is recommended to enhance notifications and enable early warning for genetic and epidemiological shifts in the human, animal and tick populations. However, a lack of guidance for surveillance in animals, harmonisation of case identification and validated serodiagnostic kits for animal testing hinders efforts to strengthen surveillance systems. Additionally, as RT-PCR tests tend to be lineage-specific for regional circulating strains, there is a need for pan-lineage sensitive diagnostics. Adaptation of existing tests to point-of-care molecular diagnostic platforms that can be implemented in clinic or field-based settings would be of value given the potential for CCHFV outbreaks in remote or low-resource areas. Finally, improved access to clinical specimens for validation of diagnostics would help to accelerate development of new tests. These gaps should be addressed by updated target product profiles for CCHFV diagnostics.

An updated roadmap for MERS-CoV research and product development: focus on diagnostics

Diagnostics play a central role in the early detection and control of outbreaks and can enable a more nuanced understanding of the disease kinetics and risk factors for the Middle East respiratory syndrome-coronavirus (MERS-CoV), one of the high-priority pathogens identified by the WHO. In this review we identified sources for molecular and serological diagnostic tests used in MERS-CoV detection, case management and outbreak investigations, as well as surveillance for humans and animals (camels), and summarised the performance of currently available tests, diagnostic needs, and associated challenges for diagnostic test development and implementation. A more detailed understanding of the kinetics of infection of MERS-CoV is needed in order to optimise the use of existing assays. Notably, MERS-CoV point-of-care tests are needed in order to optimise supportive care and to minimise transmission risk. However, for new test development, sourcing clinical material continues to be a major challenge to achieving assay validation. Harmonisation and standardisation of laboratory methods are essential for surveillance and for a rapid and effective international response to emerging diseases. Routine external quality assessment, along with well-characterised and up-to-date proficiency panels, would provide insight into MERS-CoV diagnostic performance worldwide. A defined set of Target Product Profiles for diagnostic technologies will be developed by WHO to address these gaps in MERS-CoV outbreak management.

Diagnostics for Nipah virus: a zoonotic pathogen endemic to Southeast Asia

Nipah virus (NiV) is an emerging pathogen that, unlike other priority pathogens identified by WHO, is endemic to Southeast Asia. It is most commonly transmitted through exposure to saliva or excrement from the Pteropus fruit bat, or direct contact with intermediate animal hosts, such as pigs. NiV infection causes severe febrile encephalitic disease and/or respiratory disease; treatment options are limited to supportive care. A number of in-house diagnostic assays for NiV using serological and nucleic acid amplification techniques have been developed for NiV and are used in laboratory settings, including some early multiplex panels for differentiation of NiV infection from other febrile diseases. However, given the often rural and remote nature of NiV outbreak settings, there remains a need for rapid diagnostic tests that can be implemented at the point of care. Additionally, more reliable assays for surveillance of communities and livestock will be vital to achieving a better understanding of the ecology of the fruit bat host and transmission risk to other intermediate hosts, enabling implementation of a ‘One Health’ approach to outbreak prevention and the management of this zoonotic disease. An improved understanding of NiV viral diversity and infection kinetics or dynamics will be central to the development of new diagnostics, and access to clinical specimens must be improved to enable effective validation and external quality assessments. Target product profiles for NiV diagnostics should be refined to take into account these outstanding needs.

Diagnosis of Human Immunodeficiency Virus Infection

HIV diagnostics have played a central role in the remarkable progress in identifying, staging, initiating, and monitoring infected individuals on life-saving antiretroviral therapy. They are also useful in surveillance and outbreak responses, allowing for assessment of disease burden and identification of vulnerable populations and transmission "hot spots," thus enabling planning, appropriate interventions, and allocation of appropriate funding. HIV diagnostics are critical in achieving epidemic control and require a hybrid of conventional laboratory-based diagnostic tests and new technologies, including point-of-care (POC) testing, to expand coverage, increase access, and positively impact patient management. In this review, we provide (i) a historical perspective on the evolution of HIV diagnostics (serologic and molecular) and their interplay with WHO normative guidelines, (ii) a description of the role of conventional and POC testing within the tiered laboratory diagnostic network, (iii) information on the evaluations and selection of appropriate diagnostics, (iv) a description of the quality management systems needed to ensure reliability of testing, and (v) strategies to increase access while reducing the time to return results to patients. Maintaining the central role of HIV diagnostics in programs requires periodic monitoring and optimization with quality assurance in order to inform adjustments or alignment to achieve epidemic control.

Improving pathology and laboratory medicine in low-income and middle-income countries: roadmap to solutions

Insufficient awareness of the centrality of pathology and laboratory medicine (PALM) to a functioning health-care system at policy and governmental level, with the resultant inadequate investment, has meant that efforts to enhance PALM in low-income and middle-income countries have been local, fragmented, and mostly unsustainable. Responding to the four major barriers in PALM service delivery that were identified in the first paper of this Series (workforce, infrastructure, education and training, and quality assurance), this second paper identifies potential solutions that can be applied in low-income and middle-income countries (LMICs). Increasing and retaining a quality PALM workforce requires access to mentorship and continuing professional development, task sharing, and the development of short-term visitor programmes. Opportunities to enhance the training of pathologists and allied PALM personnel by increasing and improving education provision must be explored and implemented. PALM infrastructure must be strengthened by addressing supply chain barriers, and ensuring laboratory information systems are in place. New technologies, including telepathology and point-of-care testing, can have a substantial role in PALM service delivery, if used appropriately. We emphasise the crucial importance of maintaining PALM quality and posit that all laboratories in LMICs should participate in quality assurance and accreditation programmes. A potential role for public-private partnerships in filling PALM services gaps should also be investigated. Finally, to deliver these solutions and ensure equitable access to essential services in LMICs, we propose a PALM package focused on these countries, integrated within a nationally tiered laboratory system, as part of an overarching national laboratory strategic plan.

First field evaluation of the optimized CE marked Abbott protocol for HIV RNA testing on dried blood spot in a routine clinical setting in Vietnam

Background

Viral load (VL) monitoring of HIV-infected patients in decentralized areas is limited due to logistic constraints. Dried Blood Spots (DBS) offer the opportunity to collect samples in remote area which can be easily transferred and tested at a central laboratory. The MOVIDA (Monitoring Of Viral load In Decentralized Area) project evaluated the performance of VL measurements on DBS using the new CE marked optimized Abbott protocol.

Methods

HIV-1 infected adults from three outpatient clinics in Hanoi (Vietnam) were enrolled into the study between 1 March and 13 April 2017. VL was measured on DBS using the optimized protocol provided by the manufacturer and compared to plasma VL as reference method on the Abbott m2000rt RealTime HIV-1 platform. Sensitivity was defined as the ability for DBS samples to correctly identify VL failure at the threshold of 1000 copies/mL of plasma, while specificity represented the ability to identify patients with a plasma HIV-RNA VL of <1000 copies/mL.

Results

A total of 203 patients were enrolled in the study, of which 152 (75%) were male. Median age was 38 [inter quartile range: 34–43] years. Of these patients, 37 were untreated, 38 on ART for <6 months and 117 were on ART for ≥6 months. A strong correlation between VL results in plasma and from DBS was observed (ρ = 0.95; p<0.001). Plasma VL was ≥1000 copies/mL in 71 patients. The sensitivity of DBS was 90.1% (95% confidence interval [CI]: 80.7–95.9) and the specificity was 96.2% (95% CI: 91.4–98.8).

Conclusions

The new optimized Abbott DBS protocol performed well in this study, meeting the WHO performance criteria for the use of DBS for HIV VL monitoring. Scaling up VL monitoring using DBS can be used to reach the last 90 in the UNAIDS targets of 90-90-90 to help end the AIDS epidemics. However, sensitivity remains the main challenge for manufacturers to prevent maintaining patients in virological failure on inefficient ART.

Comparison of different nucleic acid preparation methods to improve specific HIV-1 RNA isolation for viral load testing on dried blood spots

In resource-limited countries (RLCs), WHO recommends HIV viral load (VL) on dried blood spots (DBS) for antiretroviral therapy (ART) monitoring of patients living in non-urban settings where plasma VL is not available. In order to reduce the impact of proviral DNA interference, leading to false positive results in samples with low plasma VL, we compared three different nucleic acid preparation methods with the NucliSens (Biomérieux) extraction, known for its high recovery of nucleic acids on DBS. Paired plasma-DBS samples (n=151) with predominantly low plasma VL (≤10,000 copies/ml; 74%) were used. At the threshold of 1,000 copies/ml on DBS, 51% and 10% were misclassified as false positives or false negatives, respectively with NucliSens, versus 41% and 20% with m2000sp (Abbott), described as more specific for RNA recovery. DNase treatments of nucleic acid extracts and free virus elution (FVE) protocol before nucleic acid extraction, reduced the proportion of false positives to 0% and 19%, but increased the proportion of false negatives to 40% and 73%. More efforts are thus still needed to improve performance of VL assays on DBS to monitor patients on ART in RLCs and allow timely switch to more costly second or third line ART regimes.

HIV birth testing and linkage to care for HIV-infected infants

: On 5-6 May 2016, the division of AIDS of the National Institute of Allergy and Infectious Diseases convened a workshop on 'HIV Birth Testing and Linkage to Care for HIV Infected Infants.' The goal of the workshop was to evaluate birth testing for early infant diagnosis (EID) of HIV, delineate technological resources for advancing a point-of-care (POC) HIV test implementable at birth and chart out the implementation hurdles for initiating early antiretroviral therapy to HIV-infected infants diagnosed at birth. The workshop addressed research and regulatory needs involved in the optimization of POC EID testing and challenges associated with implementation of EID, focusing on testing at birth. Scientific gaps and areas of intervention to accelerate and scale-up EID initiatives and birth testing were identified. These include discussion of the evidence supporting an early mortality peak among HIV-infected infant and justifying a role for birth HIV testing, including POC testing; evaluation of the current POC EID technology pipeline and test performance characteristics required for effective programmatic uptake; mathematical modeling of different testing scenarios and solutions with inclusion of birth testing; the adoption of setting-specific EID testing algorithms to achieve efficient linkage to care including early antiretroviral therapy initiation; the development of appropriate quality assurance programs to ensure accuracy of test results and enable sustainability of the testing program. Addressing these gaps and answering these challenges will be important in helping improve outcomes for HIV-infected infants and accelerate achieving the Joint United Nations Program for HIV and AIDS 90-90-90 targets in children.