Point-of-Care Viral Load Testing for Sub-Saharan Africa: Informing a Target Product Profile

m-PIMA™ HIV1/2 VL: A suitable tool for HIV-1 and HIV-2 viral load quantification in West Africa

Point-of-Care for HIV viral RNA quantification seems to be a complementary strategy to the existing conventional systems. This study evaluated the performance of the m-PIMA™ HIV1/2 Viral Load for the quantification of both HIV-1 and HIV-2 RNA viral load. A total of 555 HIV-1 and 90 HIV-2 samples previously tested by Abbott RealTime HIV-1 (Abbott, Chicago, USA) and Generic HIV-2® Charge virale (Biocentric, France) were tested using the m-PIMA™ HIV1/2 Viral Load at the HIV National Reference lab in Senegal. For HIV-1, Pearson correlation and Bland-Altman plots showed a coefficient r = 0.97 and a bias of -0.11 log10 copies/ml (95% confidence interval [CI]: -0.086 to -0.133 log10 copies/ml) for the m-PIMA™ HIV1/2 Viral Load, respectively. Sensitivity and specificity at 3 log10 copies/ml (threshold of virological failure) were 93.6% (95%[CI]: 91.5% to 95.6%) and 99.1% (95%[CI]: 98.3% to 99.9%), respectively. For HIV-2, a correlation of r = 0.95 was also noted with a bias of - 0.229 log10 copies/ml (95%[CI]: -0.161 to -0.297 log10 copies/ml). Sensitivity and specificity at 3 log10 copies/ml were 97.6% (95%[CI]: 94.3% to 100%) and 93.9% (95%[CI]: 88.9% to 98.8%), respectively. These results confirmed that m-PIMA™ HIV1/2 VL could be a good alternative for HIV-1 and HIV-2 viral load testing in decentralized settings in Senegal.

Compact Point-of-Care Device for Self-Administered HIV Viral Load Tests from Whole Blood

Human immunodeficiency virus (HIV) is a significant problem to consider as it can lead to acquired immune deficiency syndrome (AIDS). Fortunately, AIDS is manageable through antiretroviral therapy (ART). However, frequent viral load monitoring is needed to monitor the effectiveness of the therapy. The current reverse transcription-polymerase chain reaction (RT-PCR) viral load monitoring is highly effective, but is challenged by being resource-intensive and inaccessible, and its turnaround time does not meet demand. An unmet need exists for an affordable, rapid, and user-friendly point-of-care device that could revolutionize and ensure therapeutic effectiveness, particularly in resource-limited settings. In this work, we explored a point-of-care HIV viral load device to address this need. This device can perform streamlined plasma separation, viral RNA extraction, and real-time reverse transcription loop-mediated isothermal amplification (RT-LAMP) semiquantitative testing in an ultracompact device. We developed an absorption-based membrane plasma separation method suitable for finger-prick blood samples, achieving an efficiency of 80%. We also designed a syringe-based RNA extraction method for on-site plasma processing with a viral recovery efficiency of 86%. We created a portable device with a smartphone interface for real-time semiquantitative RT-LAMP, which is useful for monitoring viral load. The device uses lyophilized reagents, processed with our lyophilization method, which remain stable for 16 weeks. The device can accurately categorize viral load into low, medium, and high categories with 95% accuracy. We believe this point-of-care HIV self-test device, offering convenience and long-term storage, could aid patients in home-based ART treatment monitoring.

Diagnostic Accuracy of the Rapid Xpert HIV-1 Viral Load XC, Xpert HIV-1 Viral Load, & m-PIMA HIV-1/2 Viral Load in South African Clinics

BACKGROUND

We aimed to evaluate the analytic performance of 3 rapid HIV viral load assays: the novel Xpert HIV-1 VL XC (Xpert XC), Xpert HIV-1 VL (Xpert VL), and m-PIMA HIV-1/2 VL (m-PIMA).

SETTING

Two South African clinics.

METHODS

We conducted a prospective diagnostic accuracy study. Site-laboratory technicians and nurses used the Xpert XC, Xpert VL, and m-PIMA to test plasma samples from people with HIV receiving antiretroviral therapy. We compared results with the Roche cobas HIV-1 reference assay. We determined accuracy to detect viraemia at the World Health Organization (WHO) failure threshold of 1000 copies/mL on all 3 assays, and 50 and 200 copies/mL on the Xpert assays. We assessed the agreement using Bland-Altman plots.

RESULTS

We enrolled 140 participants (98 [70%] women, median age 37 years), who provided 189 paired samples at one or more timepoints. We tested 174 samples with the Xpert XC, 188 with the Xpert VL, and 128 with the m-PIMA. At 1000 copies/mL, sensitivity and specificity (95% confidence intervals) were 97% (82 to 100) and 98% (93 to 99) (Xpert XC), 100% (87 to 100) and 96% (91 to 98) (Xpert VL), and 92% (72 to 99) and 99% (93 to 100) (m-PIMA) respectively. At 50 copies/mL, sensitivity and specificity were 93% (81 to 98) and 96% (91 to 99) (Xpert XC), and 95% (84 to 99) and 95% (90 to 98) (Xpert VL) respectively. Mean bias was -0.10 (-0.54 to 0.34) log10 copies/mL (Xpert XC), 0.07 (-0.37 to 0.52) log10 copies/mL (Xpert VL), and -0.26 (-0.83 to 0.31) log10 copies/mL (m-PIMA).

CONCLUSIONS

In these South African clinics, the accuracy of all 3 assays was clinically acceptable to detect viraemia at the WHO failure threshold, whereas both Xpert assays were also accurate at detecting low-level viraemia.

Impact of Motivational Enhanced Adherence Counseling and Point-of-Care Viral Load Monitoring on Viral Load Outcome in Women on Life-Long ART: A Randomized Pilot Study

We piloted the combined effectiveness of point-of-care viral load monitoring plus motivational enhanced adherence counseling (intervention) compared with routine care (control) in women identified at risk of virologic failure in the PROMOTE study in Zimbabwe. In an unblinded randomized study, consenting women with last viral load ≥200 copies/ml and/or pill count outside 90-110% range were randomized 1 : 1 to receive the intervention or continue routine care, comprising laboratory-based VL monitoring and standard EAC, from trained nurses and counsellors. Viral load was measured 0, 3, 6, and 12 months after enrolment. We compared viral suppression <200 copies/ml at 6 and 12 months between the arms through Fisher's exact test and sought associated factors by logistic regression with a 95% confidence interval (CI). Between December 2018 and July 2019, 50 women were enrolled (25 intervention and 25 controls) and followed until November 2020. At entry, 60% of the women were virally suppressed, 52% intervention vs. 68% control arm. Viral suppression was balanced between the two arms (p value = 0.248). At month 6 post study entry (primary endpont), 64% of the women retained in care were virally suppressed, 54% intervention vs. 76% control arm (p value = 0.124). At month12 post study entry (secondary endpoint), 69% of the women retained in care were virally suppressed, 67% intervention vs. 71% control arm women (p value = 0.739). More intervention women completed all scheduled sessions by month 6. Control group women were more likely to be virally suppressed at both timepoints. Only 25% had treatment switch by 12 months. Despite intense adherence support and viral load monitoring, sustained viral suppression remained elusive in women identified at risk of viral failure. These findings highlight the continued need for effective adherence intervention for women with unsuppressed HIV viral loads, efficient treatment switch strategies, as well as drug level monitoring.

Estimating the global demand curve for a leishmaniasis vaccine: A generalisable approach based on global burden of disease estimates

Background

A pressing need exists to develop vaccines for neglected diseases, including leishmaniasis. However, the development of new vaccines is dependent on their value to two key players–vaccine developers and manufacturers who need to have confidence in the global demand in order to commit to research and production; and governments (or other international funders) who need to signal demand based on the potential public health benefits of the vaccine in their local context, as well as its affordability. A detailed global epidemiological analysis is rarely available before a vaccine enters a market due to lack of resources as well as insufficient global data necessary for such an analysis. Our study seeks to bridge this information gap by providing a generalisable approach to estimating the commercial and public health value of a vaccine in development relying primarily on publicly available Global Burden of Disease (GBD) data. This simplified approach is easily replicable and can be used to guide discussions and investments into vaccines and other health technologies where evidence constraints exist. The approach is demonstrated through the estimation of the demand curve for a future leishmaniasis vaccine.

Methodology/Principal findings

We project the ability to pay over the period 2030–2040 for a vaccine preventing cutaneous and visceral leishmaniasis (CL / VL), using an illustrative set of countries which account for most of the global disease burden. First, based on previous work on vaccine demand projections in these countries and CL / VL GBD-reported incidence rates, we project the potential long-term impact of the vaccine on disability-adjusted life years (DALYs) averted as a result of reduced incidence. Then, we apply an economic framework to our estimates to determine vaccine affordability based on the abilities to pay of governments and global funders, leading to estimates of the demand and market size. Based on our estimates, the maximum ability-to-pay of a leishmaniasis vaccine (per course, including delivery costs), given the current estimates of incidence and population at risk, is higher than $5 for 25–30% of the countries considered, with the average value-based maximum price, weighted by quantity demanded, being $5.7–6 [$0.3 - $34.5], and total demand of over 560 million courses.

Conclusion/Significance

Our results demonstrate that both the quantity of vaccines estimated to be required by the countries considered as well as their ability-to-pay could make a vaccine for leishmaniasis commercially attractive to potential manufacturers. The methodology used can be equally applied to other technology developments targeting health in developing countries.

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.

Brief Report: Time to Repeat Viral Load Testing Among Unsuppressed Adolescents and Young Adults Living With HIV in Kenya

BACKGROUND

Repeat HIV viral load (VL) testing is required after unsuppressed VL to confirm treatment failure. We assessed proportion of adolescents and young adults living with HIV (AYALHIV) in Kenya with a confirmatory VL test and time to repeat testing.

DESIGN

A retrospective analysis of longitudinal data abstracted from Kenya's national VL database.

METHODS

VL data for AYALHIV who were 10-24 year old between April 2017 and May 2019 were abstracted from 117 HIV care clinics. Records were eligible if at least one VL test was performed ≥6 months after antiretroviral therapy (ART) initiation. The proportion of unsuppressed AYALHIV (≥1000 copies/mL) and time in months between first unsuppressed VL and repeat VL was determined.

RESULTS

We abstracted 40,928 VL records for 23,969 AYALHIV; of whom, 17,092 (71%) were eligible for this analysis. Of these, 12,122 (71%) were women, median age of 19 years [interquartile range (IQR): 13-23], and median ART duration of 38 months (IQR: 16-76). Among eligible AYALHIV, 4010 (23%) had an unsuppressed VL at first eligible measurement. Only 316 (8%) of the unsuppressed AYALHIV had a repeat VL within 3 months and 1176 (29%) within 6 months. Among 2311 virally unsuppressed AYALHIV with a repeat VL, the median time between the first and the repeat VL was 6 months (IQR: 4-8), with 1330 (58%) having confirmed treatment failure.

CONCLUSIONS

One-quarter of AYALHIV on ART had unsuppressed VL, with less than a third receiving a repeat VL within 6 months. Strategies to improve VL testing practices are needed to improve AYALHIV's outcomes.

Cost-effectiveness of adoption strategies for point of care HIV viral load monitoring in South Africa

BACKGROUND

Viral load (VL) testing is recommended for monitoring people on ART. The National Health Laboratory Service (NHLS) in South Africa conducts >5million laboratory-based VL tests but faces challenges with specimen integrity and results delivery. Point-of-care (POC) VL monitoring may improve VL suppression (VLS). We assessed the cost-effectiveness of different strategies for POC testing in South Africa.

METHODS

We developed a cost-outcome model utilizing NHLS data, including facility-level annual VL volumes, proportion with VLS, specimen rejection rates, turn-around-time, and the cost/test. We assessed the impact of adopting POC VL technology under 4 strategies: (1) status-quo; (2) targeted POC testing at facilities with high levels of viral failure; (3) targeted POC testing at low-performing facilities; (4) complete POC adoption. For each strategy, we determined the total cost, effectiveness (expected number of virally suppressed people) and incremental cost-effectiveness ratio (ICER) based on expected (>10%) VLS improvement.

FINDINGS

Existing laboratory-based VL testing costs $126 m annually and achieves 85.2% VLS. Strategy 2 was the most cost-effective approach, with 88.5% VLS and $40/additional person suppressed, compared to the status-quo. Should resources allow, complete POC adoption may be cost-effective (ICER: $136/additional person suppressed), requiring an additional $49 m annually and achieving 94.5% VLS. All other strategies were dominated in the incremental analysis.

INTERPRETATION

Assuming POC VL monitoring confers clinical benefits, the most cost-effective strategy for POC adoption in South Africa is a targeted approach with POC VL technologies placed at facilities with high level of viral failure.

FUNDING

Funding support from the Bill & Melinda Gates Foundation.

Point of Care Diagnostics in Resource-Limited Settings: A Review of the Present and Future of PoC in Its Most Needed Environment

Point of care (PoC) diagnostics are at the focus of government initiatives, NGOs and fundamental research alike. In high-income countries, the hope is to streamline the diagnostic procedure, minimize costs and make healthcare processes more efficient and faster, which, in some cases, can be more a matter of convenience than necessity. However, in resource-limited settings such as low-income countries, PoC-diagnostics might be the only viable route, when the next laboratory is hours away. Therefore, it is especially important to focus research into novel diagnostics for these countries in order to alleviate suffering due to infectious disease. In this review, the current research describing the use of PoC diagnostics in resource-limited settings and the potential bottlenecks along the value chain that prevent their widespread application is summarized. To this end, we will look at literature that investigates different parts of the value chain, such as fundamental research and market economics, as well as actual use at healthcare providers. We aim to create an integrated picture of potential PoC barriers, from the first start of research at universities to patient treatment in the field. Results from the literature will be discussed with the aim to bring all important steps and aspects together in order to illustrate how effectively PoC is being used in low-income countries. In addition, we discuss what is needed to improve the situation further, in order to use this technology to its fullest advantage and avoid “leaks in the pipeline”, when a promising device fails to take the next step of the valorization pathway and is abandoned.

The role of HIV viral load in mathematical models of HIV transmission and treatment: a review

Introduction

HIV viral load (VL) is accepted as a key biomarker in HIV transmission and pathogenesis. This paper presents a review of the role of VL testing in mathematical models for HIV prevention and treatment.

Methods

A search for simulation models of HIV was conducted in PubMed, yielding a total of 1210 studies. Publications before the year 2000, studies involving animals and analyses that did not use mathematical simulations were excluded. The full text of eligible articles was sourced and information about the intervention and population being modelled, type of modelling approach and disease monitoring strategy was extracted.

Results and discussion

A total of 279 studies related to HIV simulation models were included in the review, though only 17 (6%) included consideration of VL or VL testing and were evaluated in detail. Within the studies that included assessment of VL, routine monitoring was the focus, and usually in comparison to alternate monitoring strategies such as clinical or CD4 count-based monitoring. The majority of remaining models focus on the impact or delivery of antiretroviral therapy (n=68; 27%), pre-exposure prophylaxis (n=28; 11%) and/or HIV testing (n=24; 9%) on population estimates of HIV epidemiology and exclude consideration of VL. Few studies investigate or compare alternate VL monitoring frequencies, and only a small number of studies overall (3%) include consideration of vulnerable population groups such as pregnant women or infants.

Conclusions

There are very few simulations of HIV treatment or prevention that include VL measures, despite VL being recognised as the key determinant of both transmission and treatment outcomes. With growing emphasis on VL monitoring as key tool for population-level HIV control, there is a clear need for simulations of HIV epidemiology based on VL.

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.

Optimizing viral load testing access for the last mile: Geospatial cost model for point of care instrument placement

INTRODUCTION

Viral load (VL) monitoring programs have been scaled up rapidly, but are now facing the challenge of providing access to the most remote facilities (the "last mile"). For the hardest-to-reach facilities in Zambia, we compared the cost of placing point of care (POC) viral load instruments at or near facilities to the cost of an expanded sample transportation network (STN) to deliver samples to centralized laboratories.

METHODS

We extended a previously described geospatial model for Zambia that first optimized a STN for centralized laboratories for 90% of estimated viral load volumes. Amongst the remaining 10% of volumes, facilities were identified as candidates for POC placement, and then instrument placement was optimized such that access and instrument utilization is maximized. We evaluated the full cost per test under three scenarios: 1) POC placement at all facilities identified for POC; 2)an optimized combination of both on-site POC placement and placement at facilities acting as POC hubs; and 3) integration into the centralized STN to allow use of centralized laboratories.

RESULTS

For the hardest-to-reach facilities, optimal POC placement covered a quarter of HIV-treating facilities. Scenario 2 resulted in a cost per test of $39.58, 6% less than the cost per test of scenario 1, $41.81. This is due to increased POC instrument utilization in scenario 2 where facilities can act as POC hubs. Scenario 3 was the most costly at $53.40 per test, due to high transport costs under the centralized model ($36 per test compared to $12 per test in scenario 2).

CONCLUSIONS

POC VL testing may reduce the costs of expanding access to the hardest-to-reach populations, despite the cost of equipment and low patient volumes. An optimal combination of both on-site placement and the use of POC hubs can reduce the cost per test by 6-35% by reducing transport costs and increasing instrument utilization.

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.

Performance and usability of Cepheid GeneXpert HIV-1 qualitative and quantitative assay in Kenya

Background

In Kenya, access to early infant diagnosis and viral load monitoring services for HIV patients on ART is significantly hampered by sample transportation challenges and long turnaround times. Near patient care testing technologies have the potential to obviate such constraints. The Cepheid GeneXpert was launched in 2010 as a TB assay and in 2014 as a potential point of care HIV viral load assay. Whereas it is widely is used for TB in Kenya, its utility for HIV testing has not been evaluated.

Objective

To investigate the performance and usability characteristics of the GeneXpert HIV-1 qualitative and quantitative assay.

Methods

This was a cross sectional study among 911 HIV Exposed infants and 310 HIV positive adults. Existing machines used for routine TB diagnosis were used in this study. The diagnostic accuracy of the qualitative assay was assessed using Roche CAP/CTM while the quantitative assay was assessed using with Abbott m2000 as the reference assays respectively. Statistical analysis was done using Stata/MP Version 14 for Mac. Concordance values and misclassification were calculated at the clinical cutoff of 1000 cp/ml.

Results

The sensitivity, specificity and accuracy of the GeneXpert HIV-1 qualitative assay were 99.23% (95% CI 97.24–99.90%), 98.91% (95% CI 97.76–99.55%) and 99.00% respectively. For the quantitative assay, they were 92.50% (95% CI 79.61–98.43%), 100.00% and 97.00% respectively. All 30 (100%) users reported that the GeneXpert machine was easy to use, workflow was simple and TB diagnosis was not negatively affected. In our hands, the median turn-around time for an individual qualitative and quantitative test was 90 minutes. A total of 58 (4.34%) errors and 28 (2.10%) invalid outcomes were experienced; 44 (3.29%) tests did not run to completion due to power outages.

Conclusion

GeneXpert HIV-1 qualitative and quantitative assay is an accurate test for the diagnosis of HIV in infants and for viral load monitoring. At the point of care, the GeneXpert machine’s simple work flow, ease of use and short test turnaround time present the potential to improve access to HIV testing and viral load monitoring. To integrate HIV diagnosis into the existing GeneXpert platforms for TB Diagnosis, there is need to scale up the infrastructure and to change the way work is done.

Clinical effect and cost-effectiveness of incorporation of point-of-care assays into early infant HIV diagnosis programmes in Zimbabwe: a modelling study

BACKGROUND

New point-of-care (POC) assays for early infant HIV diagnosis are costlier than conventional total nucleic acid assays, but could increase access to testing, shorten time to results, and expedite initiation of antiretroviral therapy. We aimed to assess the clinical benefits and cost-effectiveness of incorporating these POC assays into early infant diagnosis programmes in Zimbabwe.

METHODS

We used the Cost Effectiveness of Preventing AIDS Complications (CEPAC)-Pediatric model to examine the clinical benefits, costs, and cost-effectiveness of replacing conventional assays for early infant HIV diagnosis with POC assays at age 6 weeks in Zimbabwe. We simulated two strategies for early infant HIV diagnosis: conventional and POC. Modelled assays differed in sensitivity; specificity; time to, and probability of, return of results; and cost. Model outcomes included survival, life expectancy, and mean lifetime per-person treatment cost, which were reported separately for all HIV-exposed infants and all infants with HIV. We calculated incremental cost-effectiveness ratios with discounted (3% per year) costs and life expectancy from a health-care system perspective for all HIV-exposed infants. We judged incremental cost-effectiveness ratios of $1010 (Zimbabwe's annual gross domestic product per person) or less per year of life saved to be cost-effective.

FINDINGS

When conventional assays were used for early infant diagnosis, projected undiscounted life expectancy was 22·7 years for infants with HIV and 62·5 years for all HIV-exposed infants, at a cost of $610 per HIV-exposed infant. Use of POC assays for early infant HIV diagnosis improved projected undiscounted life expectancy to 25·5 years among infants with HIV and 62·6 years among HIV-exposed infants at a cost of $690 per HIV-exposed infant. At age 12 weeks, survival among all infants with HIV was 76·1% with the conventional testing strategy and 83·5% with the POC testing strategy. The incremental cost-effectiveness ratio of POC assays versus conventional assays for early infant diagnosis was $680 per year of life saved. When conventional assay characteristics remained constant, this ratio remained under the cost-effectiveness threshold as long as the specificity and sensitivity of the POC assay were greater than 92% and 65%, respectively. Our results were robust to plausible variations in POC assay cost, the probability of ART initiation, and probability of return of the results of POC testing.

INTERPRETATION

Compared with conventional assays, POC assays for early infant HIV diagnosis in Zimbabwe will improve survival, extend life expectancy, and be cost-effective for HIV-exposed infants.

FUNDING

Elizabeth Glaser Pediatric AIDS Foundation, US National Institute of Allergy and Infectious Diseases, Eunice Kennedy Shriver National Institute of Child Health and Human Development, and Unitaid.

Economic and public health impact of decentralized HIV viral load testing: A modelling study in Kenya

Kenya has the world’s 4^th largest HIV burden. Various strategies to control the epidemic have been implemented, including the implementation of viral load (VL) testing to monitor HIV patients on ARVs. Like many resource limited settings, Kenya’s healthcare system faces serious challenges in effectively providing quality health services to its population. Increased investments to strengthen the country’s capacity to diagnose, monitor and treat diseases, particularly HIV and TB, continue to be made but are still inadequate in the face of global health goals like the UNAIDS 90:90:90 which require scaling up of VL tests amid existing constraints. In Kenya, there is an increase in the demand for VL tests amidst these existing constraints. The GeneXpert system is a diagnostic point-of-care technology that can quantify, amongst others, HIV VL. Currently, GeneXpert technology is widely distributed in Kenya for testing of tuberculosis. This study aimed to determine the economic and public health impact of incorporating VL test modules on the existing GeneXpert infrastructure. Markov models were constructed for different populations (non-pregnant adults, pregnant women and children). The scenarios analysed were 100% centralized VL testing compared to 50% GeneXpert plus 50% centralized VL testing, with time horizons of 5 years for the adult and child populations, and 31 months for the pregnant population. Incremental effectiveness was measured in terms of the number of HIV transmissions or opportunistic infections avoided when implementing the GeneXpert scenario compared to a 100% centralized scenario. The model indicated that, for all three populations combined, the GeneXpert scenario resulted in 117 less HIV transmissions and 393 less opportunistic infections. The cost decreased by $21,978,755 for the non-pregnant and pregnant adults and $22,808,533 for non-pregnant adults, pregnant adults and children. The model showed that GeneXpert would cost less and be more effective in terms of total cost per HIV transmission avoided and the total cost per opportunistic infection avoided, except for the pregnant population, when considered separately.

Optimal timing of viral load monitoring during pregnancy to predict viraemia at delivery in HIV-infected women initiating ART in South Africa: a simulation study

Introduction

HIV viral load (VL) monitoring is a central tool to evaluate ART effectiveness and transmission risk. There is a global movement to expand VL monitoring following recent recommendations from the World Health Organization (WHO), but there has been little research into VL monitoring in pregnant women. We investigated one important question in this area: when and how frequently VL should be monitored in women initiating ART during pregnancy to predict VL at the time of delivery in a simulated South African population.

Methods

We developed a mathematical model simulating VL from conception through delivery using VL data from the Maternal and Child Health – Antiretroviral Therapy (MCH‐ART) cohort. VL was modelled based on three major compartments: pre‐ART VL, viral decay immediately after ART initiation and viral maintenance (including viral suppression and viraemic episodes). Using this simulation, we examined the performance of various VL monitoring schema in predicting elevated VL at delivery.

Results and discussion

If WHO guidelines for non‐pregnant adults were used, the majority of HIV‐infected pregnant women (69%) would not receive a VL test during pregnancy. Most models that based VL monitoring in pregnancy on the time elapsed since ART initiation (regardless of gestation) performed poorly (sensitivity <50%); models that based VL measures in pregnancy on the woman's gestation (regardless of time on ART) appeared to perform better overall (sensitivity >60%). Across all permutations, inclusion of pre‐ART VL values had a negligible impact on predictive performance (improving test sensitivity and specificity <6%). Performance of VL monitoring in predicting VL at delivery generally improved at later gestations, with the best performing option a single VL measure at 36 weeks’ gestation.

Conclusions

Development and evaluation of a novel simulation model suggests that strategies to measure VL relative to gestational age may be more useful than strategies relative to duration on ART, in women initiating ART during pregnancy, supporting better integration of maternal and HIV health services. Testing turnaround times require careful consideration, and point‐of‐care VL testing may be the best approach for measuring VL at delivery. Broadening the scope of this simulation model in the light of current scale up of VL monitoring in high burden countries is important.

Protocol for a randomised controlled implementation trial of point-of-care viral load testing and task shifting: the Simplifying HIV TREAtment and Monitoring (STREAM) study

INTRODUCTION

Achieving the Joint United Nations Programme on HIV and AIDS 90-90-90 targets requires models of HIV care that expand antiretroviral therapy (ART) coverage without overburdening health systems. Point-of-care (POC) viral load (VL) testing has the potential to efficiently monitor ART treatment, while enrolled nurses may be able to provide safe and cost-effective chronic care for stable patients with HIV. This study aims to demonstrate whether POC VL testing combined with task shifting to enrolled nurses is non-inferior and cost-effective compared with laboratory-based VL monitoring and standard HIV care.

METHODS AND ANALYSIS

The STREAM (Simplifying HIV TREAtment and Monitoring) study is an open-label, non-inferiority, randomised controlled implementation trial. HIV-positive adults, clinically stable at 6 months after ART initiation, will be recruited in a large urban clinic in South Africa. Approximately 396 participants will be randomised 1:1 to receive POC HIV VL monitoring and potential task shifting to enrolled nurses, versus laboratory VL monitoring and standard South African HIV care. Initial clinic follow-up will be 2-monthly in both arms, with VL testing at enrolment, 6 months and 12 months. At 6 months (1 year after ART initiation), stable participants in both arms will qualify for a differentiated care model involving decentralised ART pickup at community-based pharmacies. The primary outcome is retention in care and virological suppression at 12 months from enrolment. Secondary outcomes include time to appropriate entry into the decentralised ART delivery programme, costs per virologically suppressed patient and cost-effectiveness of the intervention compared with standard care. Findings will inform the scale up of VL testing and differentiated care in HIV-endemic resource-limited settings.

ETHICS AND DISSEMINATION

Ethical approval has been granted by the University of KwaZulu-Natal Biomedical Research Ethics Committee (BFC296/16) and University of Washington Institutional Review Board (STUDY00001466). Results will be presented at international conferences and published in academic peer-reviewed journals.

TRIAL REGISTRATION

NCT03066128; Pre-results.

Point-of-care diagnostics: extending the laboratory network to reach the last mile

Purpose of review

More point-of-care (POC) diagnostic tests are becoming available for HIV diagnosis and treatment in resource-limited settings. These novel technologies have the potential to foster decentralized HIV care and treatment for the benefit of clinical laboratories, HIV clinics, and HIV-infected patients. There continue to be many business, technological, and operational challenges that limit product development and regulatory approval, which limits products available for the required operational and cost-effectiveness studies and delays policy adoption and implementation.

Recent findings

Although the rapid HIV diagnostic test has been widely successful, the pathways for POC CD4⁺ cell count and HIV viral load assay analyzers have been more challenging. We describe significant hurdles for product development, approval, and implementation, which include the business case, technical development, clinical impact, and integrating laboratory and clinical networks.

Summary

The objective of this review is to highlight the obstacles for developing and implementing appropriate strategies for POC HIV testing assays to improve the clinical services for HIV-infected patients in resource-limited settings.