Cost-effectiveness of point-of-care testing with task-shifting for HIV care in South Africa: a modelling study

Towards the development of cost-effective point-of-care diagnostic tools for poverty-related infectious diseases in sub-Saharan Africa

In this review, we examine the current landscape of point-of-care testing (POCT) diagnostic tools designed for poverty-related infectious diseases (PRIDs) in sub-Saharan Africa (sSA) while delineating key avenues for future advancements. Our analysis encompasses both established and emerging diagnostic methods for PRIDs, addressing the persistent challenges in POCT tool development and deployment, such as cost, accessibility, and reliability. We emphasize recent advancements in POCT diagnostic tools as well as platforms poised to enhance diagnostic testing in sSA. Recognizing the urgency for affordable and widely accessible POCT diagnostic tools to detect PRIDs in sSA, we advocate for a multidisciplinary approach. This approach integrates current and emerging diagnostic methods, explicitly addressing challenges hindering point-of-care (POC) tool development. Furthermore, it recognizes the profound impact of misdiagnosis on public and global health, emphasizing the need for effective tools. To facilitate the successful development and implementation of POCT diagnostic tools in sSA, we propose strategies including the creation of multi-analyte detection POCT tools, the implementation of education and training programs, community engagement initiatives, fostering public-private collaborations, and the establishment of reliable supply chains. Through these concerted efforts, we aim to accelerate the development of POCT in the sSA region, ensuring its effectiveness and accessibility in addressing the diagnostic challenges associated with PRIDs.

A Generalizable Decision-Making Framework for Selecting Onsite versus Send-out Clinical Laboratory Testing

BACKGROUND

Laboratory networks provide services through onsite testing or through specimen transport to higher-tier laboratories. This decision is based on the interplay of testing characteristics, treatment characteristics, and epidemiological characteristics.

OBJECTIVES

Our objective was to develop a generalizable model using the threshold approach to medical decision making to inform test placement decisions.

METHODS

We developed a decision model to compare the incremental utility of onsite versus send-out testing for clinical purposes. We then performed Monte Carlo simulations to identify the settings under which each strategy would be preferred. Tuberculosis was modeled as an exemplar.

RESULTS

The most important determinants of the decision to test onsite versus send-out were the clinical utility lost due to send-out testing delays and the accuracy decrement with onsite testing. When the sensitivity decrements of onsite testing were minimal, onsite testing tended to be preferred when send-out delays reduced clinical utility by >20%. By contrast, when onsite testing incurred large reductions in sensitivity, onsite testing tended to be preferred when utility lost due to delays was >50%. The relative cost of onsite versus send-out testing affected these thresholds, particularly when testing costs were >10% of treatment costs.

CONCLUSIONS

Decision makers can select onsite versus send-out testing in an evidence-based fashion using estimates of the percentage of clinical utility lost due to send-out delays and the relative accuracy of onsite versus send-out testing. This model is designed to be generalizable to a wide variety of use cases.

HIGHLIGHTS

The design of laboratory networks, including the decision to place diagnostic instruments at the point-of-care or at higher tiers as accessed through specimen transport, can be informed using the threshold approach to medical decision making.The most important determinants of the decision to test onsite versus send-out were the clinical utility lost due to send-out testing delays and the accuracy decrement with onsite testing.The threshold approach to medical decision making can be used to compare point-of-care testing accuracy decrements with the lost utility of treatment due to send-out testing delays.The relative cost of onsite versus send-out testing affected these thresholds, particularly when testing costs were >10% of treatment costs.

Using queueing models as a decision support tool in allocating point-of-care HIV viral load testing machines in Kisumu County, Kenya

Point-of-care (POC) technologies-including HIV viral load (VL) monitoring-are expanding globally, including in resource-limited settings. Modelling could allow decision-makers to consider the optimal strategy(ies) to maximize coverage and access, minimize turnaround time (TAT) and minimize cost with limited machines. Informed by formative qualitative focus group discussions with stakeholders focused on model inputs, outputs and format, we created an optimization model incorporating queueing theory and solved it using integer programming methods to reflect HIV VL monitoring in Kisumu County, Kenya. We modelled three scenarios for sample processing: (1) centralized laboratories only, (2) centralized labs with 7 existing POC 'hub' facilities and (3) centralized labs with 7 existing and 1-7 new 'hub' facilities. We calculated total TAT using the existing referral network for scenario 1 and solved for the optimal referral network by minimizing TAT for scenarios 2 and 3. We conducted one-way sensitivity analyses, including distributional fairness in each sub-county. Through two focus groups, stakeholders endorsed the provisionally selected model inputs, outputs and format with modifications incorporated during model-building. In all three scenarios, the largest component of TAT was time spent at a facility awaiting sample batching and transport (scenarios 1-3: 78.7%, 89.9%, 91.8%) and waiting time at the testing site (18.7%, 8.7%, 7.5%); transportation time contributed minimally to overall time (2.6%, 1.3%, 0.7%). In scenario 1, the average TAT was 39.8 h (SD: 2.9), with 1077 h that samples spent cumulatively in the VL processing system. In scenario 2, the average TAT decreased to 33.8 h (SD: 4.8), totalling 430 h. In scenario 3, the average TAT decreased nearly monotonically with each new machine to 31.1 h (SD: 8.4) and 346 total hours. Frequency of sample batching and processing rate most impacted TAT, and inclusion of distributional fairness minimally impacted TAT. In conclusion, a stakeholder-informed resource allocation model identified optimal POC VL hub allocations and referral networks. Using existing-and adding new-POC machines could markedly decrease TAT, as could operational changes.

Feasibility, Acceptability and Appropriateness of MedViewer: A Novel Hair-Based Antiretroviral Real-Time Clinical Monitoring Tool Providing Adherence Feedback to Patients and Their Providers

Antiretroviral therapy (ART) adherence is key to achieving viral load suppression and ending the HIV epidemic but monitoring and supporting adherence using current interventions is challenging. We assessed the feasibility, acceptability and appropriateness of MedViewer (MV), a novel intervention that provides real-time adherence feedback for patients and providers using infra-red matrix-assisted laser desorption electrospray ionization (IR-MALDESI) for mass spectrometry imaging of daily ART concentrations in patients' hair. We used mixed methods to feasibility test MV at a busy Infectious Diseases (ID) clinic, enrolling 16 providers and 36 patients. Providers underwent standardized training; patients and providers watched an 8-min informational video about MV. We collected patient and provider data at baseline and within 24 h of clinic visits and, with patients, approximately 1 month after clinic visits. MedViewer was feasible, liked by patients and providers, and perceived to help facilitate adherence conversations and motivate patients to improve adherence. Trial Registration: NCT04232540.

Transmission reduction, health benefits, and upper-bound costs of interventions to improve retention on antiretroviral therapy: a combined analysis of three mathematical models

BACKGROUND

In this so-called treat-all era, antiretroviral therapy (ART) interruptions contribute to an increasing proportion of HIV infections and deaths. Many strategies to improve retention on ART cost more than standard of care. In this study, we aimed to estimate the upper-bound costs at which such interventions should be adopted.

METHODS

In this combined analysis, we compared the infections averted, disability-adjusted life-years (DALYs) averted, and upper-bound costs of interventions that improve ART retention in three HIV models with diverse structures, assumptions, and baseline settings: EMOD in South Africa, Optima in Malawi, and Synthesis in sub-Saharan African low-income and middle-income countries (LMICs). We modelled estimates over a 40-year time horizon, from a baseline of Jan 1, 2022, when interventions would be implemented, to Jan 1, 2062. We varied increment of ART retention (25%, 50%, 75%, and 100% retention), the extent to which interventions could be targeted towards individuals at risk of interrupting ART, and cost-effectiveness thresholds in each setting.

FINDINGS

Despite simulating different settings and epidemic trends, all three models produced consistent estimates of health benefit (ie, DALYs averted) and transmission reduction per increment in retention. The range of estimates was 1·35-3·55 DALYs and 0·12-0·20 infections averted over the 40-year time horizon per additional person-year retained on ART. Upper-bound costs varied by setting and intervention effectiveness. Improving retention by 25% among all people receiving ART, regardless of risk of ART interruption, gave an upper-bound cost per person-year of US$2-6 in Optima (Malawi), $43-68 in Synthesis (LMICs in sub-Saharan Africa), and $28-180 in EMOD (South Africa). A maximally targeted and effective retention intervention had an upper-bound cost per person-year of US$93-223 in Optima (Malawi), $871-1389 in Synthesis (LMICs in sub-Saharan Africa), and $1013-6518 in EMOD (South Africa).

INTERPRETATION

Upper-bound costs that could improve ART retention vary across sub-Saharan African settings and are likely to be similar to or higher than was estimated before the start of the treat-all era. Upper-bound costs could be increased by targeting interventions to those most at risk of interrupting ART.

FUNDING

Bill & Melinda Gates Foundation.

Provider perspectives on the use of motivational interviewing and problem-solving counseling paired with the point-of-care nucleic acid test for HIV care

Aims

To evaluate provider perspectives on the use of a point-of-care nucleic acid test (POC NAT) and preferential opinions for motivational interviewing (MI) or problem-solving counseling (PSC) as an ultra-brief intervention for patients experiencing challenges to antiretroviral therapy (ART) adherence.

Methods

A qualitative study was conducted among providers at an HIV care clinic in Seattle, Washington. Ten in-depth interviews with HIV care providers were completed, which explored determinants of acceptability, feasibility and preferences for a combined adherence counseling and POC NAT intervention for patients living with HIV. Interviews were analyzed through consensus coding and the Five A’s Framework to inform thematic analysis.

Results

Providers favored the use of a combined adherence counseling technique and POC NAT for their non-adherent patients living with HIV. Providers believed the intervention was an improvement on current assessment and advising practices. However, concerns about extended wait times for the POC NAT results influenced perceptions about feasibility around clinic flow and incorporation into clinic practice. Providers believed that acceptability of POC NAT implementation would be enhanced by including a subset of patient populations whom tend to be in the clinic for longer periods, and in tandem face greater ART adherence challenges.

Conclusion

The GAIN Study will be the first project to evaluate the implementation of POC NAT in the U.S. Continued formative work is ongoing and may illustrate how best to address feasibility and concern around the two-hour time to result. The planned GAIN study will incorporate some of the findings found in this qualitative study and pilot this intervention, including a time-in-motion analyses of clinic flow, which may help reduce perceived wide-scale adaptation of POC NAT and ART adherence counselling among PLHW. Future work, including a shorter time to results and/or lower limit detection could make a significant improvement in the provision of HIV care.

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.

Real-Time Infectious Disease Modeling to Inform Emergency Public Health Decision Making

Infectious disease transmission is a nonlinear process with complex, sometimes unintuitive dynamics. Modeling can transform information about a disease process and its parameters into quantitative projections that help decision makers compare public health response options. However, modelers face methodologic challenges, data challenges, and communication challenges, which are exacerbated under the time constraints of a public health emergency. We review methods, applications, challenges and opportunities for real-time infectious disease modeling during public health emergencies, with examples drawn from the two deadliest pandemics in recent history: HIV/AIDS and coronavirus disease 2019 (COVID-19).

Expected final online publication date for the Annual Review of Public Health, Volume 43 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

The risks and benefits of providing HIV services during the COVID-19 pandemic

INTRODUCTION

The COVID-19 pandemic has caused widespread disruptions including to health services. In the early response to the pandemic many countries restricted population movements and some health services were suspended or limited. In late 2020 and early 2021 some countries re-imposed restrictions. Health authorities need to balance the potential harms of additional SARS-CoV-2 transmission due to contacts associated with health services against the benefits of those services, including fewer new HIV infections and deaths. This paper examines these trade-offs for select HIV services.

METHODS

We used four HIV simulation models (Goals, HIV Synthesis, Optima HIV and EMOD) to estimate the benefits of continuing HIV services in terms of fewer new HIV infections and deaths. We used three COVID-19 transmission models (Covasim, Cooper/Smith and a simple contact model) to estimate the additional deaths due to SARS-CoV-2 transmission among health workers and clients. We examined four HIV services: voluntary medical male circumcision, HIV diagnostic testing, viral load testing and programs to prevent mother-to-child transmission. We compared COVID-19 deaths in 2020 and 2021 with HIV deaths occurring now and over the next 50 years discounted to present value. The models were applied to countries with a range of HIV and COVID-19 epidemics.

RESULTS

Maintaining these HIV services could lead to additional COVID-19 deaths of 0.002 to 0.15 per 10,000 clients. HIV-related deaths averted are estimated to be much larger, 19-146 discounted deaths per 10,000 clients.

DISCUSSION

While there is some additional short-term risk of SARS-CoV-2 transmission associated with providing HIV services, the risk of additional COVID-19 deaths is at least 100 times less than the HIV deaths averted by those services. Ministries of Health need to take into account many factors in deciding when and how to offer essential health services during the COVID-19 pandemic. This work shows that the benefits of continuing key HIV services are far larger than the risks of additional SARS-CoV-2 transmission.

Lay testing cadres and point-of-care diagnostic tests for HIV and other diseases: An essential combination in health service delivery

Zibusiso Ndlovu and Tom Ellman discuss the potential value of task sharing in provision of testing for HIV and other infectious diseases.

Simplifying TREAtment and Monitoring for HIV (STREAM HIV): protocol for a randomised controlled trial of point-of-care urine tenofovir and viral load testing to improve HIV outcomes

INTRODUCTION

Substantial improvements in viral suppression among people living with HIV (PLHIV) are needed to end the HIV epidemic, requiring extensive scale-up of low-cost HIV monitoring services. Point-of-care (POC) tests for monitoring antiretroviral therapy (ART) adherence and viral load (VL) may be efficient and effective tools for real-time clinical decision making. We aim to evaluate the effects of a combined intervention of POC ART adherence and VL testing compared with standard-of-care on ART adherence, viral suppression and retention at 6 and 18 months post-ART initiation among PLHIV.

METHODS AND ANALYSIS

Simplifying TREAtment and Monitoring for HIV (STREAM HIV) is a two-arm, open-label, randomised controlled superiority trial of POC urine tenofovir (POC TFV) and VL monitoring in PLHIV. We aim to enrol 540 PLHIV initiating a first-line ART regimen at a public HIV clinic in South Africa. Participants will be randomised 1:1 to the intervention or control arm. Intervention arm participants will receive monthly POC TFV testing for the first 5 months and POC VL testing at months 6 and 12. Intervention arm participants will also receive reflex POC TFV testing if viraemic and reflex HIV drug resistance testing for those with viraemia and detectable TFV. Control arm participants will receive standard-of-care, including laboratory-based VL testing at months 6 and 12. Primary outcomes include ART adherence (TFV-diphosphate concentration) at 6 months and viral suppression and retention at 18 months. Secondary outcomes include viral suppression and retention at 6 months, TFV-diphosphate concentration at 18 months, cost and cost-effectiveness of the intervention and acceptability of the intervention among PLHIV and healthcare workers.

ETHICS AND DISSEMINATION

STREAM HIV has received ethical approval from the University of Washington Institutional Review Board (STUDY00007544), University of KwaZulu-Natal Biomedical Research Ethics Committee (BREC/00000833/2019) and Division of AIDS Regulatory Support Center (38509). Findings will be disseminated at international conferences and in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04341779.

Costs of Point-of-Care Viral Load Testing for Adults and Children Living with HIV in Kenya

BACKGROUND

The number of people living with HIV (PLHIV) in need of treatment monitoring in low-and-middle-income countries is rapidly expanding, straining existing laboratory capacity. Point-of-care viral load (POC VL) testing can alleviate the burden on centralized laboratories and enable faster delivery of results, improving clinical outcomes. However, implementation costs are uncertain and will depend on clinic testing volume. We sought to estimate the costs of decentralized POC VL testing compared to centralized laboratory testing for adults and children receiving HIV care in Kenya.

METHODS

We conducted microcosting to estimate the per-patient costs of POC VL testing compared to known costs of centralized laboratory testing. We completed time-and-motion observations and stakeholder interviews to assess personnel structures, staff time, equipment costs, and laboratory processes associated with POC VL administration. Capital costs were estimated using a 5 year lifespan and a 3% annual discount rate.

RESULTS

We estimated that POC VL testing cost USD $24.25 per test, assuming a clinic is conducting 100 VL tests per month. Test cartridge and laboratory equipment costs accounted for most of the cost (62% and 28%, respectively). Costs varied by number of VL tests conducted at the clinic, ranging from $54.93 to $18.12 per test assuming 20 to 500 VL tests per month, respectively. A VL test processed at a centralized laboratory was estimated to cost USD $25.65.

CONCLUSION

POC VL testing for HIV treatment monitoring can be feasibly implemented in clinics within Kenya and costs declined with higher testing volumes. Our cost estimates are useful to policymakers in planning resource allocation and can inform cost-effectiveness analyses evaluating POC VL testing.