Dataset Information

Performance of the Xpert HIV-1 Viral Load Assay: a Systematic Review and Meta-analysis.

ABSTRACT: Viral load (VL) is the preferred treatment-monitoring approach for HIV-positive patients. However, more rapid, near-patient, and low-complexity assays are needed to scale up VL testing. The Xpert HIV-1 VL assay (Cepheid, Sunnyvale, CA) is a new, automated molecular test, and it can leverage the GeneXpert systems that are being used widely for tuberculosis diagnosis. We systematically reviewed the evidence on the performance of this new tool in comparison to established reference standards. A total of 12 articles (13 studies) in which HIV patient VLs were compared between Xpert HIV VL assay and a reference standard VL assay were identified. Study quality was generally high, but substantial variability was observed in the number and type of agreement measures reported. Correlation coefficients between Xpert and reference assays were high, with a pooled Pearson correlation (n = 8) of 0.94 (95% confidence interval [CI], 0.89, 0.97) and Spearman correlation (n = 3) of 0.96 (95% CI, 0.86, 0.99). Bland-Altman metrics (n = 11) all were within 0.35 log copies/ml of perfect agreement. Overall, Xpert HIV-1 VL performed well compared to current reference tests. The minimal training and infrastructure requirements for the Xpert HIV-1 VL assay make it attractive for use in resource-constrained settings, where point-of-care VL testing is most needed.

SUBMITTER: Nash M

PROVIDER: S-EPMC5869835 | biostudies-other | 2018 Apr

REPOSITORIES: biostudies-other

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Performance of the Xpert HIV-1 Viral Load Assay: a Systematic Review and Meta-analysis.

Nash Madlen M Huddart Sophie S Badar Sayema S Baliga Shrikala S Saravu Kavitha K Pai Madhukar M

Journal of clinical microbiology 20180326 4

Viral load (VL) is the preferred treatment-monitoring approach for HIV-positive patients. However, more rapid, near-patient, and low-complexity assays are needed to scale up VL testing. The Xpert HIV-1 VL assay (Cepheid, Sunnyvale, CA) is a new, automated molecular test, and it can leverage the GeneXpert systems that are being used widely for tuberculosis diagnosis. We systematically reviewed the evidence on the performance of this new tool in comparison to established reference standards. A tot ...[more]

PMID: 29386266

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Project description:IntroductionGuidelines for antiretroviral therapy recommend enhanced adherence counselling be provided to individuals with an initial elevated viral load before making a decision whether to switch antiretroviral regimen. We undertook this systematic review to estimate the proportion of patients with an initial elevated viral load who resuppress following enhanced adherence counselling.MethodsTwo databases and two conference abstract sites were searched from January 2012 to October 2019 for studies reporting the number of patients with an elevated viral load whose viral load was undetectable when subsequently assessed. Data were pooled using random effects meta-analysis.ResultsFifty-eight studies reported outcomes of 45,720 viraemic patients, mostly from Africa (48 studies), and among patients on first-line antiretroviral therapy (43 studies). Almost half (46.1%, 95% CI 42.6% to 49.5%) of patients with an initial elevated viral load resuppressed following an enhanced adherence intervention. Of those on first-line ART with confirmed virological failure (6280 patients, 21 studies), only 53.4% (40.1% to 66.8%) were appropriately switched to a different regimen. Resuppression was higher among studies that provided details of adherence support. The proportion resuppressing was lower among children (31.2%, 21.1% to 41.3%) and adolescents (40.4%, 15.7% to 65.2%) compared to adults (50.4%, 42.6% to 58.3%). No important differences were observed by date of study publication, gender, viral failure threshold, publication status, time between viral loads or treatment regimen. Information on resistance testing among people with an elevated viral load was inconsistently reported.ConclusionsThe findings of this review suggest that in settings with limited resources, current guideline recommendations to provide enhanced adherence counselling can result in resuppression of a substantial number of these patients, avoiding unnecessary drug regimen changes. Appropriate action on viral load results is limited across a range of settings, highlighting the importance of viral load cascade analyses to identify gaps and focus quality improvement to ensure that action is taken on the results of viral load testing.

Project description:Viral load (VL) monitoring is the standard of care in developing country settings for detecting HIV treatment failure. Since 2010 the World Health Organization has recommended a phase-in approach to VL monitoring in resource-limited settings. We conducted a systematic review of the accuracy and precision of HIV VL technologies for treatment monitoring.A search of Medline and Embase was conducted for studies evaluating the accuracy or reproducibility of commercially available HIV VL assays. 37 studies were included for review including evaluations of the Amplicor Monitor HIV-1 v1.5 (n?=?25), Cobas TaqMan v2.0 (n?=?11), Abbott RealTime HIV-1 (n?=?23), Versant HIV-1 RNA bDNA 3.0 (n?=?15), Versant HIV-1 RNA kPCR 1.0 (n?=?2), ExaVir Load v3 (n?=?2), and NucliSens EasyQ v2.0 (n?=?1). All currently available HIV VL assays are of sufficient sensitivity to detect plasma virus levels at a lower detection limit of 1,000 copies/mL. Bias data comparing the Abbott RealTime HIV-1, TaqMan v2.0 to the Amplicor Monitor v1.5 showed a tendency of the Abbott RealTime HIV-1 to under-estimate results while the TaqMan v2.0 overestimated VL counts. Compared to the Amplicor Monitor v1.5, 2-26% and 9-70% of results from the Versant bDNA 3.0 and Abbott RealTime HIV-1 differed by greater than 0.5log10. The average intra and inter-assay variation of the Abbott RealTime HIV-1 were 2.95% (range 2.0-5.1%) and 5.44% (range 1.17-30.00%) across the range of VL counts (2log10-7log10).This review found that all currently available HIV VL assays are of sufficient sensitivity to detect plasma VL of 1,000 copies/mL as a threshold to initiate investigations of treatment adherence or possible treatment failure. Sources of variability between VL assays include differences in technology platform, plasma input volume, and ability to detect HIV-1 subtypes. Monitoring of individual patients should be performed on the same technology platform to ensure appropriate interpretation of changes in VL. Prospero registration # CD42013003603.

Project description:BackgroundAccurate 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 findingsStandard 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.ConclusionsThis 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.

Dataset Information

Performance of the Xpert HIV-1 Viral Load Assay: a Systematic Review and Meta-analysis.

Publications

Performance of the Xpert HIV-1 Viral Load Assay: a Systematic Review and Meta-analysis.

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