Evaluation of the performance of Abbott m2000 and Roche COBAS Ampliprep/COBAS Taqman assays for HIV-1 viral load determination using dried blood spots and dried plasma spots in Kenya

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.

Revolutionizing HIV-1 Viral Load Monitoring in India: The Potential of Dried Blood Spot Analysis for Expanding Access and Improving Care

India continues to grapple with a significant burden of HIV infections. Despite notable progress in prevention and treatment efforts, multiple challenges, such as high-risk populations, inadequate testing facilities, and limited access to healthcare in remote areas, persist. Though the Government of India offers HIV-1 plasma viral load testing at various medical centers, aiding treatment decisions and monitoring antiretroviral therapy effectiveness, enhancing care for individuals living with HIV under the National AIDS Control Program (NACP), the nation's large population and diverse demographics further complicate its outreach and response. Hence, strategic interventions and alternative methods of testing remain crucial to curbing HIV transmission and improving the quality of life for those affected. Dried blood spot (DBS) sampling has emerged as a convenient and cost-effective alternative for HIV-1 viral load testing, revolutionizing the landscape of diagnostic and monitoring strategies for HIV infection. Though the plasma-based viral load remains the gold standard for monitoring HIV-1, DBS-based HIV-1 viral load testing holds immense promise for improving access to care, particularly in resource-limited settings where traditional plasma-based methods may be logistically challenging. DBS entails the collection of a small volume of blood onto filter paper, followed by drying and storage. This approach offers numerous advantages, including simplified sample collection, transportation, and storage, reducing the need for cold-chain logistics. Recent studies have demonstrated the feasibility and accuracy of DBS-based HIV-1 viral load testing, revealing a strong correlation between DBS and plasma measurements. Its implementation can enhance the early detection of treatment failure, guide therapeutic decisions, and ultimately contribute to better clinical outcomes for HIV-infected individuals. Hence, this review explores the principles, advancements, feasibility, and implications of DBS-based HIV-1 viral load testing.

Performance of two plasma separation devices for HIV-1 viral load measurement in primary healthcare settings

IMPORTANCE

Burnett and HemaSpot are two novel technologies that allow whole blood collection and plasma separation and stabilization at room temperature without the need of additional equipment. Hence, these devices are potential alternatives to fresh plasma as a suitable specimen for viral load scale-up to monitor antiretroviral therapy in resource-limited settings.

Biological Fluid Microsampling for Therapeutic Drug Monitoring: A Narrative Review

Therapeutic drug monitoring (TDM) is a specialized area of laboratory medicine which involves the measurement of drug concentrations in biological fluids with the aim of optimizing efficacy and reducing side effects, possibly modifying the drug dose to keep the plasma concentration within the therapeutic range. Plasma and/or whole blood, usually obtained by venipuncture, are the "gold standard" matrices for TDM. Microsampling, commonly used for newborn screening, could also be a convenient alternative to traditional sampling techniques for pharmacokinetics (PK) studies and TDM, helping to overcome practical problems and offering less invasive options to patients. Although technical limitations have hampered the use of microsampling in these fields, innovative techniques such as 3-D dried blood spheroids, volumetric absorptive microsampling (VAMS), dried plasma spots (DPS), and various microfluidic devices (MDS) can now offer reliable alternatives to traditional samples. The application of microsampling in routine clinical pharmacology is also hampered by the need for instrumentation capable of quantifying analytes in small volumes with sufficient sensitivity. The combination of microsampling with high-sensitivity analytical techniques, such as liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), is particularly effective in ensuring high accuracy and sensitivity from very small sample volumes. This manuscript provides a critical review of the currently available microsampling devices for both whole blood and other biological fluids, such as plasma, urine, breast milk, and saliva. The purpose is to provide useful information in the scientific community to laboratory personnel, clinicians, and researchers interested in implementing the use of microsampling in their routine clinical practice.

Virologic Nonsuppression Among Patients With HIV Newly Diagnosed With Cancer at Uganda Cancer Institute: A Cross-Sectional Study

PURPOSE

AIDS-related mortality declined markedly since the introduction of antiretroviral therapy (ART); however, cancer mortality in Africa was higher than its incidence in 2020. People living with HIV (PLWHIV) are at an increased risk of malignancy and death from malignancy compared with the general population. In Uganda, AIDS-defining malignancies (ADMs), including cervical cancer, Kaposi sarcoma, and non-Hodgkin lymphoma, are among the commonest malignancies. Virologic nonsuppression has been identified as an important predictor of mortality among PLWHIV diagnosed with cancer. This study aimed to determine the prevalence and to identify factors associated with virologic nonsuppression among PLWHIV newly diagnosed with cancer.

METHODS

This was a cross-sectional study that was carried out between December 2018 and April 2019 at the Uganda Cancer Institute. PLWHIV who had been on ART for at least 6 months and were newly diagnosed with cancer were enrolled.

RESULTS

A total of 167 participants were enrolled. Cervical cancer was the commonest ADM (n = 45; 50.6%) of all ADMs, while esophageal and breast cancers were the commonest non-ADMs, accounting for 17.5% (n = 14) each of all non-ADMs. The prevalence of virologic nonsuppression was 15%. Having Kaposi sarcoma (odds ratio [OR], 8.15; P = .003), being poorly adherent to ART (OR, 4.1; P = .045), and being on second-line ART (OR, 5.68; P = .011) were associated with virologic nonsuppression.

CONCLUSION

The prevalence of virologic nonsuppression is high among patients with HIV newly diagnosed with cancer. These findings emphasize the need for strengthening of adherence strategies, optimizing ART regimens, and prioritization of viral load testing among PLWHIV with newly diagnosed malignancy.

Microsampling tools for collecting, processing, and storing blood at the point-of-care

In the wake of the COVID-19 global pandemic, self-administered microsampling tools have reemerged as an effective means to maintain routine healthcare assessments without inundating hospitals or clinics. Finger-stick collection of blood is easily performed at home, in the workplace, or at the point-of-care, obviating the need for a trained phlebotomist. While the initial collection of blood is facile, the diagnostic or clinical utility of the sample is dependent on how the sample is processed and stored prior to transport to an analytical laboratory. The past decade has seen incredible innovation for the development of new materials and technologies to collect low-volume samples of blood with excellent precision that operate independently of the hematocrit effect. The final application of that blood (i.e., the test to be performed) ultimately dictates the collection and storage approach as certain materials or chemical reagents can render a sample diagnostically useless. Consequently, there is not a single microsampling tool that is capable of addressing every clinical need at this time. In this review, we highlight technologies designed for patient-centric microsampling blood at the point-of-care and discuss their utility for quantitative sampling as a function of collection material and technique. In addition to surveying methods for collecting and storing whole blood, we emphasize the need for direct separation of the cellular and liquid components of blood to produce cell-free plasma to expand clinical utility. Integrating advanced functionality while maintaining simple user operation presents a viable means of revolutionizing self-administered microsampling, establishing new avenues for innovation in materials science, and expanding access to healthcare.

Assessment of HIV viral load monitoring in remote settings in Vietnam - comparing people who inject drugs to the other patients

INTRODUCTION

Increasing access to viral load (VL) monitoring is essential to fight HIV epidemics. In remote settings in Vietnam, using dried blood spot (DBS) sampling for specimen collection could improve the situation. Here, people who inject drugs (PWID) represent many newly antiretroviral therapy (ART)-initiated patients. The goals of this evaluation were to evaluate if access to VL monitoring and the rate of virological failure differed between PWID and non-PWID.

METHODS

Prospective cohort study of patients newly initiated on ART in remote settings in Vietnam. DBS coverage at 6, 12 and 24 months of ART was investigated. Factors associated with DBS coverage were identified through logistic regression, as were factors associated with virological failure (VL ≥1,000 copies/mL) at 6, 12 and 24 months of ART.

RESULTS

Overall 578 patients were enrolled in the cohort, of whom 261 (45%) were PWID. DBS coverage improved from 74.7% to 82.9% between 6 and 24 months of ART (p = 0.001). PWID status was not associated with DBS coverage (p = 0.74), but DBS coverage was lower in patients who were late to clinical visits and in those in WHO stage 4 (p = 0.023 and p = 0.001, respectively). The virological failure rate decreased from 15.8% to 6.6% between 6 and 24 months of ART (p<0.001). In multivariate analysis, PWID were more at risk of failure (p = 0.001), as were patients who were late to clinical visits (p<0.001) and not fully adherent (p<0.001).

CONCLUSIONS

Despite training and simple procedures, DBS coverage was not perfect. DBS coverage was not associated with PWID status. Close management is required for effective routine HIV VL monitoring. PWID were more at risk of failure, as were patients who were not fully adherent and patients who were late to clinical visits. Specific interventions targeting these patients are needed to improve their outcomes. Overall, efforts in coordination and communication are essential to improve global HIV care.

TRIAL REGISTRATION

Clinical Trial Number: NCT03249493.

Potential use of a dried saliva spot (DSS) in therapeutic drug monitoring and disease diagnosis

In recent years, scientific researchers have increasingly become interested in noninvasive sampling methods for therapeutic drug monitoring and disease diagnosis. As a result, dried saliva spot (DSS), which is a sampling technique for collecting dried saliva samples, has been widely used as an alternative matrix to serum for the detection of target molecules. Coupling the DSS method with a highly sensitive detection instrument improves the efficiency of the preparation and analysis of biological samples. Furthermore, dried blood spots, dried plasma spots, and dried matrix spots, which are similar to those of the DSS method, are discussed. Compared with alternative biological fluids used in dried spot methods, including serum, tears, urine, and plasma, saliva has the advantage of convenience in terms of sample collection from children or persons with disabilities. This review aims to provide integral strategies and guidelines for dried spot methods to analyze biological samples by illustrating several dried spot methods. Herein, we summarize recent advancements in DSS methods from June 2014 to March 2021 and discuss the advantages and disadvantages of the key aspects of this method, including sample preparation and method validation. Finally, we outline the challenges and prospects of such methods in practical applications.

The performance of using dried blood spot specimens for HIV-1 viral load testing: A systematic review and meta-analysis

BACKGROUND

Accurate routine HIV viral load testing is essential for assessing the efficacy of antiretroviral treatment (ART) regimens and the emergence of drug resistance. While the use of plasma specimens is the standard for viral load testing, its use is restricted by the limited ambient temperature stability of viral load biomarkers in whole blood and plasma during storage and transportation and the limited cold chain available between many health care facilities in resource-limited settings. Alternative specimen types and technologies, such as dried blood spots, may address these issues and increase access to viral load testing; however, their technical performance is unclear. To address this, we conducted a meta-analysis comparing viral load results from paired dried blood spot and plasma specimens analyzed with commonly used viral load testing technologies.

METHODS AND FINDINGS

Standard databases, conferences, and gray literature were searched in 2013 and 2018. Nearly all studies identified (60) were conducted between 2007 and 2018. Data from 40 of the 60 studies were included in the meta-analysis, which accounted for a total of 10,871 paired dried blood spot:plasma data points. We used random effects models to determine the bias, accuracy, precision, and misclassification for each viral load technology and to account for between-study variation. Dried blood spot specimens produced consistently higher mean viral loads across all technologies when compared to plasma specimens. However, when used to identify treatment failure, each technology compared best to plasma at a threshold of 1,000 copies/ml, the present World Health Organization recommended treatment failure threshold. Some heterogeneity existed between technologies; however, 5 technologies had a sensitivity greater than 95%. Furthermore, 5 technologies had a specificity greater than 85% yet 2 technologies had a specificity less than 60% using a treatment failure threshold of 1,000 copies/ml. The study's main limitation was the direct applicability of findings as nearly all studies to date used dried blood spot samples prepared in laboratories using precision pipetting that resulted in consistent input volumes.

CONCLUSIONS

This analysis provides evidence to support the implementation and scale-up of dried blood spot specimens for viral load testing using the same 1,000 copies/ml treatment failure threshold as used with plasma specimens. This may support improved access to viral load testing in resource-limited settings lacking the required infrastructure and cold chain storage for testing with plasma specimens.

Diagnostic Accuracy of Dried Plasma Spot Specimens for HIV-1 Viral Load Testing: A Systematic Review and Meta-analysis

BACKGROUND

Dried plasma spot specimens may be a viable alternative to traditional liquid plasma in field settings, but the diagnostic accuracy is not well understood.

METHODS

Standard databases (PubMed and Medline), conferences, and gray literature were searched until January 2019. The quality of evidence was evaluated using the Standards for Reporting Studies of Diagnostic Accuracy and Quality Assessment of Diagnostic Accuracy Studies-2 criteria. We used univariate and bivariate random effects models to determine misclassification, sensitivity, and specificity across multiple thresholds, overall and for each viral load technology, and to account for between-study variation.

RESULTS

We identified 23 studies for inclusion in the systematic review that compared the diagnostic accuracy of dried plasma spots with that of plasma. Primary data from 16 of the 23 studies were shared and included in the meta-analysis, representing 18 countries, totaling 1847 paired dried plasma spot:plasma data points. The mean bias of dried plasma spot specimens compared with that of plasma was 0.28 log10 copies/mL, whereas the difference in median viral load was 2.25 log10 copies/mL. More dried plasma spot values were undetectable compared with plasma values (43.6% vs. 29.8%). Analyzing all technologies together, the sensitivity and specificity of dried plasma spot specimens were >92% across all treatment failure thresholds compared and total misclassification <5.4% across all treatment failure thresholds compared. Some technologies had lower sensitivity or specificity; however, the results were typically consistent across treatment failure thresholds.

DISCUSSION

Overall, dried plasma spot specimens performed relatively well compared with plasma with sensitivity and specificity values greater than 90% and misclassification rates less than 10% across all treatment failure thresholds reviewed.

Stability of HIV-1 Nucleic Acids in cobas Plasma Separation Card for Viral Load Measurement

OBJECTIVES

Our study aimed to evaluate the stability of human immunodeficiency virus 1 (HIV-1) RNA on cobas plasma separation card (PSC) specimens for viral load (VL) testing after being exposed to varied temperatures and storage times.

METHODS

For this purpose, venous PSC specimens were collected and stored at 25ºC to 42ºC for a period of up to 28 days. Plasma VL at baseline was used as reference, against which PSC VL was compared at different time points.

RESULTS

From the 30 patients included in the study, 600 PSC and 30 fresh plasma specimens were obtained. Plasma VL at baseline was fewer than 1,000 copies/mL in 16 patients, and 99.4% of PSCs from these patients yielded nonquantifiable VL at all temperature ranges and time points. During the study period, minor variation of VL was observed in PSCs obtained from 13 patients with plasma VL fewer than 1,000 copies/mL at baseline. For the patient with plasma VL at 1,000 copies/mL, the PSC VL varied from undetectable to 1,670 copies/mL.

CONCLUSIONS

Our results show minor variation of VL in PSC specimens in the study conditions. HIV RNA is stable in PSCs exposed to high temperatures for up to 28 days.

Human Immunodeficiency Virus Infection in Adolescents and Mode of Transmission in Southern Africa: A Multinational Analysis of Population-Based Survey Data

Background

Adolescents aged 10–19 years living with human immunodeficiency virus (HIV) (ALHIV), both perinatally infected adolescents (APHIV) and behaviorally infected adolescents (ABHIV), are a growing population with distinct care needs. We characterized the epidemiology of HIV in adolescents included in Population-based HIV Impact Assessments (2015–2017) in Zimbabwe, Malawi, Zambia, Eswatini, and Lesotho.

Methods

Adolescents were tested for HIV using national rapid testing algorithms. Viral load (VL) suppression (VLS) was defined as VL <1000 copies/mL, and undetectable VL (UVL) as VL <50 copies/mL. Recent infection (within 6 months) was measured using a limiting antigen avidity assay, excluding adolescents with VLS or with detectable antiretrovirals (ARVs) in blood. To determine the most likely mode of infection, we used a risk algorithm incorporating recency, maternal HIV and vital status, history of sexual activity, and age at diagnosis.

Results

HIV prevalence ranged from 1.6% in Zambia to 4.8% in Eswatini. Of 707 ALHIV, 60.9% (95% confidence interval, 55.3%–66.6%) had HIV previously diagnosed, and 47.1% (41.9%–52.3%) had VLS. Our algorithm estimated that 72.6% of ALHIV (485 of 707) were APHIV, with HIV diagnosed previously in 69.5% of APHIV and 39.4% of ABHIV, and with 65.3% of APHIV and 33.5% of ABHIV receiving ARV treatment. Only 67.2% of APHIV and 60.5% of ABHIV receiving ARVs had UVL.

Conclusions

These findings suggest that two-thirds of ALHIV were perinatally infected, with many unaware of their status. The low prevalence of VLS and UVL in those receiving treatment raises concerns around treatment effectiveness. Expansion of opportunities for HIV diagnoses and the optimization of treatment are imperative.

Prospective evaluation of accuracy of HIV viral load monitoring using the Aptima HIV Quant Dx assay with fingerstick and venous dried blood spots prepared under field conditions in Kenya

Quantification of HIV-1 RNA is essential for clinical management of HIV patients. The limited throughput and significant hands-on time required by most HIV Viral load (VL) tests makes it challenging for laboratories with high test volume, to turn around patient results quickly. The Hologic Aptima HIV-1 Quant Dx Assay (Aptima), has the potential to alleviate this burden as it is high throughput and fully automated. This assay is validated for both plasma and dried blood spots (DBS), which are commonly used in resource limited settings. The objective of this study was to compare the performance of Aptima to Abbott RealTime HIV-1 Assay (Abbott RT), which was used as reference. This was a cross-sectional prospective study where HIV VL in finger stick (FS) DBS, venous blood (VB) DBS and plasma, collected from 258 consenting adults visiting 5 medical facilities in Kenya, Africa were tested in Aptima. The results were compared to plasma VL in Abbott RT at the medical decision point (MDP) of 1000 copies/mL and across Aptima assay range. The total agreement at MDP between plasma HIV VL in Abbott RT and plasma, FS and VB DBS tested in Aptima were 97.7%, 92.2% and 95.3% respectively with kappa statistic of 0.95, 0.84 and 0.90. The positive and negative agreement for all 3 sample types were >92%. Regression analysis between VL in Abbott RT plasma and various sample types tested in Aptima had a Pearson's correlation coefficient ≥0.91 with systematic bias of < 0.20 log copies/mL on Bland-Altman analysis. The high level of agreement in Aptima HIV VL results for all 3 sample types with Abbott RT plasma VL along with the high throughput, complete automation, and ease of use of the Panther platform makes Aptima a good option for HIV VL monitoring for busy laboratories with high volume of testing.

Field evaluation of HIV-1 viral load monitoring in adults and children receiving antiretroviral treatment in Nigeria by dried blood spot testing with RealTime HIV-1 on m2000

In resource-limited settings, use of dried blood spots (DBS) could be a pragmatic alternative to plasma for VL monitoring in people living with HIV (PLWH). We compared results from DBS to standard plasma VL testing under field conditions in patients receiving antiretroviral therapy (ART). DBS cards were prepared from venous blood (V-DBS), finger-pricks using micro-capillary tubes (M-DBS), and direct spotting (D-DBS). DBS and matched EDTA plasma were tested on the Abbott m2000 platform using the appropriate RealTime HIV-1 quantitative CE protocol. Matched plasma samples were also tested on the Roche COBAS Ampliprep/COBAS TaqMan version 2.0. Diagnostic accuracy indicators (sensitivity, specificity, misclassification rate, and kappa coefficient) for viral failure (VF) based on different VL threshold levels and agreement of absolute VL were calculated. A total of 669 participants provided 2676 samples. V-DBS had a peak sensitivity for VF of 89.1 % [95 % CI: 85.5-92.7] at the 1000 copies/mL threshold and a peak specificity of 97.4 % [95 % CI: 95.9-99.0] at the 5000 copies/mL threshold. The lowest proportion of upward misclassification (patients classified with VF who actually had viral suppression) for V-DBS was 3.1 % [95 % CI: 1.4-4.8] at the 5000 copies/mL threshold, whereas the lowest proportion of downward misclassification (patients classified as undetectable who actually had VF) was 10.9 % [95 % CI: 7.2-14.5] at the 1000 copies/mL threshold. Abbott RealTime HIV-1 VL results from all 3 DBS types for adults and children showed strong correlation with the gold standard plasma-based assay. DBS could be useful for monitoring VL in resource limited settings such as Nigeria.

The Development of a Standardized Quality Assessment Material to Support Xpert® HIV-1 Viral Load Testing for ART Monitoring in South Africa

The tiered laboratory framework for human immunodeficiency virus (HIV) viral load monitoring accommodates a range of HIV viral load testing platforms, with quality assessment critical to ensure quality patient testing. HIV plasma viral load testing is challenged by the instability of viral RNA. An approach using an RNA stabilizing buffer is described for the Xpert^® HIV-1 Viral Load (Cepheid) assay and was tested in remote laboratories in South Africa. Plasma panels with known HIV viral titres were prepared in PrimeStore molecular transport medium for per-module verification and per-instrument external quality assessment. The panels were transported at ambient temperatures to 13 testing laboratories during 2017 and 2018, tested according to standard procedures and uploaded to a web portal for analysis. A total of 275 quality assessment specimens (57 verification panels and two EQA cycles) were tested. All participating laboratories met study verification criteria (n = 171 specimens) with an overall concordance correlation coefficient (ρ_c) of 0.997 (95% confidence interval (CI): 0.996 to 0.998) and a mean bias of −0.019 log copies per milliliter (cp/mL) (95% CI: −0.044 to 0.063). The overall EQA ρ_c (n = 104 specimens) was 0.999 (95% CI: 0.998 to 0.999), with a mean bias of 0.03 log cp/mL (95% CI: 0.02 to 0.05). These panels are suitable for use in quality monitoring of Xpert^® HIV-1 VL and are applicable to laboratories in remote settings.

Accuracy of quantitative HIV-1 RNA test methods at 1000 copies/mL and the potential impact of differences in assay calibration on therapy monitoring of patients

The World Health Organization (WHO) recommends the clinical use of a human immunodeficiency virus 1 (HIV-1) viral load (VL) threshold level of 1000 copies (cp)/mL in patients on antiretroviral therapy (ART) to distinguish between viral control (VL < 1000 cp/mL) and viral failure or poor adherence (VL > 1000 cp/mL). The accuracy of five quantitative HIV-1 RNA assays at this level was compared by replicate testing (n = 24) of 1000 cp/mL samples prepared from the Viral Quality Control (VQC) HIV-1 subtype B standard, which is in use for validation of nucleic acid testing methods since 1995. Until 2004 the VL assays reported geometric mean (95% confidence interval [CI]) values ranging between 449 (188-1067) and 3162 (3057-2367) cp/mL when using the Siemens bDNA 3.0 assay as reference method for an assigned value of 1000 (962-1038) cp/mL. In 2018, the following values (95% CI) were found by 24 replicate tests in each of the VL assays on the 1000 cp/mL samples: Abbott RealTime 1084 (784-1572), BioMerieux EasyQ 1110 (533-2230), Roche CAP/CTM 1277 (892-1828), Hologic Aptima 1616 (1324-1973), and Cepheid GeneXpert 2502 (1713-3655) cp/mL. Calibration studies involving three consecutive WHO replacement standards showed a significant drift in the amount of RNA copies per International Unit overtime. Heat inactivation of HIV-1 standards was found to cause a destandardizing effect. Our study underlines the limitations in HIV-1 RNA assay calibration based on frequently replaced WHO international standards. It is therefore proposed that clinicians interpret the recommended 1000 cp/mL alert level in therapy monitoring with an inaccuracy range of 500 to 2000 cp/mL.

HIV-1 viral load testing in resource-limited settings: Challenges and solutions for specimen integrity

HIV-1 viral load (VL) testing is a crucial element in providing an antiretroviral treatment monitoring program. The success of these programs depends on the availability and quality of the VL testing services. There are several pre-analytic factors which can affect the quality of VL testing. Many of the challenges faced by resource-limited countries result in a compromise of specimen integrity, thus limiting widespread access to VL monitoring. The various logistic and financial challenges that exist are not insurmountable and several innovative solutions currently exist to overcome these barriers to providing widespread VL testing. This review summarizes the VL testing challenges in resource-limited settings and provides an overview of potential solutions including testing dried blood spots, dried plasma spots, plasma separation cards and the use of point of care tests.

Whatman FTA cards versus plasma specimens for the quantitation of HIV-1 RNA using two real-time PCR assays

Background

Several studies have compared the use of dried blot spot (DBS) as an alternative to plasma specimens, mainly using Whatman 903 cards as filter paper. The aim of this study was to evaluate the use of Whatman FTA card (FTA card) specimens for HIV-1 viral load testing compared to plasma specimens using two real-time PCR assays manufactured by Roche and Abbott.

Methodology

A cross-sectional study was conducted between April 2017 and September 2017 on HIV-1 patients admitted to Yalgado Ouédraogo Teaching Hospital. Paired FTA cards and plasma specimens were collected and analysed using the Abbott Real-Time HIV-1 assay (Abbott) and COBAS AmpliPrep/COBAS TaqMan v2.0 (Roche).

Results

In total, 107 patients were included. No statistical differences (P>0.05) were observed between the mean viral loads obtained from the FTA cards and those of the plasma specimens using the Roche and Abbott assays. In total, 29 samples with Roche and 15 samples with Abbott assay showed discrepant results. At viral loads of ≤1000 copies ml⁻¹, the sensitivity and specificity of the FTA cards were 78.6 and 100% with Roche, and 92.3 and 95.9% with Abbott, respectively. Both the Roche and Abbott assays showed good correlation and agreement between the FTA cards and plasma values.

Conclusion

Our study demonstrates the feasibility of using FTA card filter paper for HIV-1 viral load testing. However, further studies will be required for the validation of the use of FTA card filter paper in HIV-1 treatment monitoring.

Comparison of Alere q whole blood viral load with DBS and plasma viral load in the classification of HIV virological failure

Background

In remote settings, timely plasma separation and transportation to testing laboratories is an impediment to the access of HIV viral load (VL) testing. Potential solutions are whole blood testing through point of care (POC) assays or dried blood spots (DBS).

Methods

We evaluated the performance of a prototype Alere q whole blood VL protocol and compared it against plasma (Abbott RealTime HIV-1) and DBS VL (Abbott RealTime HIV-1 DBS revised prototype protocol and Roche CAP/CTM HIV-1 v2.0 DBS free virus elution protocol). Virological failure (VF) was defined at >1000 copies/ml.

Results

Of 299 samples, Alere q correctly classified VF in 61% versus 87% by Abbott DBS and 76% by Roche FVE. Performance varied across plasma VL categories. Alere q showed 100% sensitivity. Below 1000 copies/ml of plasma, Alere q demonstrated over-quantification, with 19% specificity. Abbott DBS had 91% sensitivity and the best overall correlation with plasma (r² = 0.72). Roche FVE had the best specificity of 99% but reduced sensitivity of 52%, especially between 1000–10,000 copies/ml of plasma. Correlation was best for all assays at >10,000 copies/ml.

Conclusion

Variability was prominent between the assays. Each method requires optimization to facilitate the implementation of a cut-off with optimal sensitivity and specificity for VF. Although Alere q whole blood assay exhibited excellent sensitivity, the poor specificity of only 19% would lead to unnecessary switching of regimens. Thus any VF detected would need to be confirmed by a more specific assay. Both the Abbott DBS and Roche FVE protocols showed good specificity, however sensitivity was reduced when the plasma VL was 1000–10,000 copies/ml. This could result in delays in detecting VF and accumulation of drug resistance. Field evaluation in settings that have adopted these DBS protocols are necessary.

Accurate HIV viral load measurement in primary health care settings using the cobas® plasma separation card

Introduction

Plasma is considered the gold standard for HIV viral load (VL) testing, however its use is challenging due to the need for phlebotomy and centrifugation services, as well as cold chain for transporting to laboratories for testing. The use of Dried Blood Spot (DBS) specimen has allowed a rapid expansion of antiretroviral therapy (ART) monitoring in remote areas in many African countries, however, the VL in DBS may overestimate the copies of viral RNA result at the clinically relevant range of 1000 copies/ml, due to proviral DNA and intracellular RNA. The characteristics of the cobas^® Plasma Separation Card (PSC) specimen are similar to fresh plasma (gold standard), so a better performance of HIV VL is expetected in PSC specimen and can be an alternative to DBS. This study aims to evaluate the performance of cobas^® PSC for VL testing at primary health care facilities in Mozambique.

Methodology

HIV-1 infected adults on ART were enrolled consecutively in two health facilities in Mozambique, between August 2018 and October 2018. Capillary and venous cobas^® PSC, DBS and fresh plasma specimens were collected from each patient. All specimens were tested for VL using CAP/CTM v2.0. Sensitivity and specificity of viral load using DBS, capillary and venous PSC specimens were estimated. Viral load obtained in fresh plasma specimen was used as reference and a threshold of 1000 copies/ml was considered for the analyses.

Results

From the total 613 patients included for the study, 2444 specimens including DBS (613), plasma (613), venous cobas^® PSC (609) and capillary cobas^® PSC (609) were collected and 2407 results were obtained. Sensitivity and specificity of the VL using venous cobas^®PSC specimen at 1000 copies/ml threshold were 99.8% and 98.1% respectively, whereas for capillary cobas^® PSC sensitivity was 99.6% and specificity was 97.2%. For DBS VL, sensitivity was 96.9% and specificity was 81.8%. Misclassification rate was more prominent in DBS specimens (5.9%), but lower in venous and capillary cobas^®PSC with a rate of 0.3% and 0.7% respectively.

Conclusion

The cobas^® PSC specimen has improved performance over DBS for more accurate VL testing aligned with plasma testing. The use of this specimen type can increase the rates of reliable VL results and this will improve the quality of VL monitoring of HIV-positive patients in low-income settings.

Feasibility of dried blood spots for HIV viral load monitoring in decentralized area in North Vietnam in a test-and-treat era, the MOVIDA project

Background

Access to HIV viral load is crucial to efficiently monitor patients on antiretroviral treatment (ART) and prevent HIV drug resistance acquisition. However, in some remote settings, access to viral load monitoring is still complex due to logistical and financial constraints. Use of dried blood spots (DBS) for blood collection could overcome these difficulties. This study aims to describe feasibility and operability of DBS use for routine viral load monitoring.

Methods

From June 2017 to April 2018, HIV-infected adults who initiated ART were enrolled in a prospective cohort in 43 clinical sites across 6 provinces in North Vietnam. Following national guidelines, the first viral load monitoring was planned 6 months after ART initiation. DBS were collected at the clinical site and sent by post to a central laboratory in Hanoi for viral load measurement.

Results

Of the 578 patients enrolled, 537 were still followed 6 months after ART initiation, of which DBS was collected for 397 (73.9%). The median (inter quartile range) delay between DBS collection at site level and reception at the central laboratory was 8 (6–19) days and for 70.0% viral load was measured ≤30 days after blood collection. The proportion of patients with viral load ≥1000 copies/mL at the 6 month evaluation was 15.9% (n = 59). Of these, a DBS was collected again to confirm virological failure in 15 (24.4%) of which virological failure was confirmed in 11 (73.3%).

Conclusion

Delay of DBS transfer to the central laboratory was acceptable and most viral loads were measured in ≤30 days, in-line with routine follow-up. However, the level of DBS coverage and the proportion of patients in failure for whom a confirmatory viral load was available were suboptimal, indicating that integration of viral load monitoring in the field requires, among other things, careful training and strong involvement of the local teams. The proportion of patients experiencing virological failure was in line with other reports; interestingly those who reported being non-adherent and those with a low BMI were more at risk of failure.

Use of viral load to improve survey estimates of known HIV-positive status and antiretroviral treatment coverage

OBJECTIVE

To compare alternative methods of adjusting self-reported knowledge of HIV-positive status and antiretroviral (ARV) therapy use based on undetectable viral load (UVL) and ARV detection in blood.

DESIGN

Post hoc analysis of nationally representative household survey to compare alternative biomarker-based adjustments to population HIV indicators.

METHODS

We reclassified HIV-positive participants aged 15-64 years in the 2012 Kenya AIDS Indicator Survey (KAIS) who were unaware of their HIV-positive status by self-report as aware and on antiretroviral treatment if either ARVs were detected or viral load was undetectable (<550 copies/ml) on dried blood spots. We compared self-report to adjustments for ARV measurement, UVL, or both.

RESULTS

Treatment coverage among all HIV-positive respondents increased from 31.8% for self-report to 42.5% [95% confidence interval (CI) 37.4-47.8] based on ARV detection alone, to 42.8% (95% CI 37.9-47.8) when ARV-adjusted, 46.2% (95% CI 41.3-51.1) when UVL-adjusted and 48.8% (95% CI 43.9-53.8) when adjusted for either ARV or UVL. Awareness of positive status increased from 46.9% for self-report to 56.2% (95% CI 50.7-61.6) when ARV-adjusted, 57.5% (95% CI 51.9-63.0) when UVL-adjusted, and 59.8% (95% CI 54.2-65.1) when adjusted for either ARV or UVL.

CONCLUSION

Undetectable viral load, which is routinely measured in surveys, may be a useful adjunct or alternative to ARV detection for adjusting survey estimates of knowledge of HIV status and antiretroviral treatment coverage.

Cost and Impact of Dried Blood Spot Versus Plasma Separation Card for Scale-up of Viral Load Testing in Resource-limited Settings

BACKGROUND

Routine plasma viral load (VL) testing is recommended for monitoring human immunodeficiency virus-infected patients on antiretroviral therapy. In Zambia, VL scale-up is limited due to logistical obstacles around plasma specimen collection, storage, and transport to centralized laboratories. Dried blood spots (DBSs) could circumvent many logistical challenges at the cost of increased misclassification. Recently, plasma separation cards (PSCs) have become available and, though more expensive, have lower total misclassification than DBSs.

METHODS

Using a geospatial model created for optimizing VL utilization in Zambia, we estimated the short-term cost of uptake/correct VL result using either DBSs or PSCs to increase VL access on equipment available in-country. Five scenarios were modeled: (1) plasma only (status quo); (2) plasma at high-volume sites, DBS at low-volume sites; (3) plasma at high-volume sites, PSC at low-volume sites; (4) PSC only; (5) DBS only.

RESULTS

Scenario 1 resulted in 795 342 correct results due to limited patient access. When allowing for full and partial adoption of dried specimens, access increases by 19%, with scenario 3 producing the greatest number of correct results expected (929 857). The average cost per correct VL result was lowest in the plasma + DBS scenario at $30.90 compared to $31.62 in our plasma + PSC scenario. The cost per correct result of using dried specimens only was dominated in the incremental analysis, due primarily to fewer correct results.

CONCLUSIONS

Adopting the partial use of dried specimens will help achieve improved VL access for patients at the lowest cost per correct result.

HIV RNA measurement in dried blood spots of HIV-infected patients in Thailand using Abbott m2000 system

World Health Organization recommends using dried blood spots (DBS) for HIV RNA viral load (VL) measurement whenever plasma processing is not convenient or feasible. DBS collected from 80 treatment-naïve HIV-infected patients presenting in three hospitals of two different regions of Thailand were shipped to a central laboratory along with corresponding plasma specimens. Viral load was measured in both DBS and plasma using the Abbott m2000 system. HIV RNA levels were strongly correlated (r = 0.94) with a mean of differences of 0.23 log₁₀ copies/mL. Using the 1,000 copies/mL cut-off, the sensitivity of DBS was 97% (95%CI, 91–100%) and specificity was 75% (95%CI, 19–99%). DBS are useful to scale-up HIV RNA VL testing in settings with limited access to VL testing.

Development and validation of a simple and rapid way to generate low volume of plasma to be used in point-of-care HIV virus load technologies

A new point-of-care HIV viral load, mPIMA HIV-1/2 VL, Abbott, USA, has been recently developed. This point-of-care viral load requires no skilled person to run and uses a small plasma volume (50 μL). However, obtaining 50 μL of plasma can be a challenge in limited resource settings. We validated a simple and easy method to obtain enough amount of plasma to run a point-of-care viral load. The study utilized 149 specimens from patients failing antiretroviral therapy. At least 250 μL of whole blood was collected in a microtube/EDTA from fingerstick (fs-plasma) and immediately centrifuged. Parallel collection of venous blood to obtain plasma (vp-plasma) was used to compare performance in a point-of-care viral load assay and in methodology used in centralized laboratories Abbott M2000, Abbott, USA. The procedure for plasma collection takes less than 10 min and in 94% of the cases only one fingerstick was sufficient to collect at least 250 μL of blood. The Pearson correlation coefficient value for vp-plasma versus fs-plasma ran on mPIMA was 0.990. The Bland–Altman mean difference (md) for this comparison were virtually zero (md = −0.001) with limits of agreement between −0.225 and 0.223. In addition, the Pearson correlation coefficient value for fs-plasma in mPIMA versus vp-plasma in Abbott M2000 was 0.948 for values above the mPIMA limit of quantification (LoQ; from 800 to 1,000,000 copies/mL). These results validate this simple plasma isolation method capable to be implemented in low resource countries where point-of-care decentralization is deeply needed.

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.

Adherence Measurements in HIV: New Advancements in Pharmacologic Methods and Real-Time Monitoring

PURPOSE OF REVIEW

In this review, we present new developments in antiretroviral adherence, focusing on pharmacological measures and real-time adherence monitoring. In addition, new strategies on how to incorporate these new measures into research and clinical care are proposed.

RECENT FINDINGS

Antiretroviral drug concentrations in hair and dried blood spots are two novel pharmacological measures of cumulative drug adherence and exposure that have been recently evaluated in HIV treatment and pre-exposure prophylaxis. Real-time adherence monitoring using electronic devices has also proven highly informative, feasible, and well accepted, offering the possibility for an immediate intervention when non-adherence is detected. Both approaches offer considerable advantages over traditional adherence measures in predicting efficacy. New methods to objectively monitor adherence in real-time and over long time periods have been developed. Further research is required to better understand how these measures can optimize adherence and, ultimately, improve clinical outcomes in HIV treatment and prevention.

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.