False-positive HIV test results in infancy and management of uninfected children receiving antiretroviral therapy

Use of an Indeterminate Range in HIV Early Infant Diagnosis: A Systematic Review and Meta-Analysis

BACKGROUND

Expanded access to HIV antiretrovirals has dramatically reduced mother-to-child transmission of HIV. However, there is increasing concern around false-positive HIV test results in perinatally HIV-exposed infants but few insights into the use of indeterminate range to improve infant HIV diagnosis.

METHODS

A systematic review and meta-analysis was conducted to evaluate the use of an indeterminate range for HIV early infant diagnosis. Published and unpublished studies from 2000 to 2018 were included. Study quality was evaluated using GRADE and QUADAS-2 criteria. A random-effects model compared various indeterminate ranges for identifying true and false positives.

RESULTS

The review identified 32 studies with data from over 1.3 million infants across 14 countries published from 2000 to 2018. Indeterminate results accounted for 16.5% of initial non-negative test results, and 76% of indeterminate results were negative on repeat testing. Most results were from Roche tests. In the random-effects model, an indeterminate range using a polymerase chain reaction cycle threshold value of ≥33 captured over 93% of false positives while classifying fewer than 9% of true positives as indeterminate.

CONCLUSIONS

Without the use of an indeterminate range, over 10% of infants could be incorrectly diagnosed as HIV positive if their initial test results are not confirmed. Use of an indeterminate range appears to lead to substantial improvements in the accuracy of early infant diagnosis testing and supports current recommendations to confirm all initial positive tests.

Utility Of POC Xpert HIV-1 Tests For Detection-Quantification Of Complex HIV Recombinants Using Dried Blood Spots From Kinshasa, D. R. Congo

Point-of-Care (POC) molecular assays improve HIV infant diagnosis and viral load (VL) quantification in resource-limited settings. We evaluated POC performance in Kinshasa (Democratic Republic of Congo), with high diversity of HIV-1 recombinants. In 2016, 160 dried blood samples (DBS) were collected from 85 children (60 HIV-, 18 HIV+, 7 HIV-exposed) and 75 HIV+ adults (65 treated, 10 naive) at Monkole Hospital (Kinshasa). We compared viraemia with Cepheid-POC-Xpert-HIV-1VL and the non-POC-COBAS®AmpliPrep/COBAS®TaqMan®HIV-1-Testv2 in all HIV+, carrying 72.4%/7.2% HIV-1 unique/complex recombinant forms (URF/CRF). HIV-1 infection was confirmed in 14 HIV+ children by Cepheid-POC-Xpert-HIV-1Qual and in 70 HIV+ adults by both Xpert-VL and Roche-VL, identifying 8 false HIV+ diagnosis performed in DRC (4 adults, 4 children). HIV-1 was detected in 95.2% and 97.6% of 84 HIV+ samples by Xpert-VL and Roche-VL, respectively. Most (92.9%) HIV+ children presented detectable viraemia by both VL assays and 74.3% or 72.8% of 70 HIV+ adults by Xpert or Roche, respectively. Both VL assays presented high correlation (R2 = 0.89), but showing clinical relevant ≥0.5 log VL differences in 15.4% of 78 cases with VL within quantification range by both assays. This is the first study confirming the utility of Xpert HIV-1 tests for detection-quantification of complex recombinants currently circulating in Kinshasa.

Differentiating clearly positive from indeterminate results: A review of irreproducible HIV-1 PCR positive samples from South Africa's Early Infant Diagnosis Program, 2010-2015

We describe the extent of and variables associated with irreproducible HIV-1 PCR positive results within South Africa's Early Infant Diagnosis (EID) program from 2010 to 2015 and propose criteria for differentiating indeterminate from clearly positive results using the COBAS® AmpliPrep/COBAS® TaqMan HIV-1 Qualitative Test version 2.0 (CAP/CTM Qual v2.0). Fourteen percent of specimens with an instrument-positive result that were repeat-tested yielded a negative result for which cycle threshold (Ct) proved to be the only predictive variable. A Ct <33.0 was found to be the most accurate threshold value for differentiating clearly positive from irreproducible cases, correctly predicting 96.8% of results. Among 70 patients with an irreproducible positive result linked to a follow up HIV-1 PCR test, 67 (95.7%) were negative and 3 (4.3%) were instrument-positive. Criteria differentiating clearly positive from indeterminate results need to be retained within EID services and infants with indeterminate results closely monitored and final HIV status determined.

Prevalence and outcomes of HIV-1 diagnostic challenges during universal birth testing - an urban South African observational cohort

Introduction: HIV‐1 polymerase chain reaction (PCR) testing at birth aims to facilitate earlier initiation of antiretroviral therapy (ART) for HIV‐infected neonates. Data from two years of universal birth testing implementation in a high‐burden South African urban setting are presented to demonstrate the prevalence and outcomes of diagnostic challenges in this context.

Methods: HIV‐exposed neonates born at Rahima Moosa Mother and Child Hospital between 5 June 2014 and 31 August 2016 were routinely screened at birth for HIV‐1 on whole blood samples using the COBAS® AmpliPrep/COBAS® TaqMan (CAP/CTM) HIV‐1 Qualitative Test, version 2.0 (Roche Molecular Systems, Inc., Branchburg, NJ, USA). Virological results were interpreted according to standard operating procedures with the South African National Health Laboratory Service. All neonates with non‐negative results were actively followed‐up and categorized according to HIV infection status as positive, negative, uncertain and lost to follow‐up (LTFU).

Results: 104 (1.8%) of 5743 HIV‐exposed neonates received a non‐negative birth PCR result, for which laboratory data were available for 102 (98%) cases – 78 (76%) tested positive and 24 (24%) indeterminate. HIV infection status was confirmed positive in 83 (81%) infants, negative in 8 (8%), uncertain in 5 (5%) and LTFU in 6 (6%) cases. The positive predictive value (excluding cases of uncertain diagnosis and inadequate testing) following a non‐negative HIV‐1 PCR screening test at birth was 0.91 (83/91; 95% confidence interval: 0.85–0.96). Neonates testing positive at birth had significantly higher viral load (VL) results than those testing indeterminate at birth of 4.5 and 3.0 log copies/ml (p = 0.0007), respectively. Similarly, mothers of neonates with positive as compared to indeterminate birth test results had higher VLs of 4.5 and 2.7 log copies/ml (p = 0.0013), respectively. Half of neonates with an indeterminate birth test were shown to be HIV‐infected on subsequent confirmatory testing, with time to final diagnosis 30 days longer for these neonates (p < 0.0001).

Conclusion: Indeterminate HIV‐1 PCR results accounted for a quarter of non‐negative results at birth and were associated with a high risk of infection in comparison to the risk of in utero transmission. Indeterminate birth results with positive HIV PCR results on repeat testing were associated with later final diagnosis. The HIV‐1 status remains uncertain in a minority of cases because of repeatedly indeterminate results, highlighting the need for more sensitive and specific virological tests.

Evaluation of four commercial virological assays for early infant HIV-1 diagnosis using dried blood specimens

BACKGROUND

Early infant diagnosis (EID) of HIV-1 is necessary to reduce HIV-related mortality. As maternal antibodies transferred across the placenta may persist up to 18 mo, commercial virological assays (CVAs) are needed. This study compares four CVAs for EID using dried blood specimens (DBS) from HIV-1-exposed infants.

METHODS

DBS from 68 infants born to HIV-1-infected women were collected from November 2012 to December 2013 in Equatorial Guinea. Four CVAs were performed: Siemens VERSANT HIV-1 RNA 1.0 kPCR assay, Roche CAP/CTM Quantitative Test v2.0, CAP/CTM Qualitative Tests v1.0 and v2.0. Definitive diagnosis was established following World Health Organization (WHO) recommendations.

RESULTS

Two HIV-1-infected infants (2.9%) were detected by the four CVAs while 49 (72%) resulted negative. Discordant results were observed in 17 (25%) infants and HIV-1 infection was excluded in 14 patients when virological and serological testing was performed in additional DBS. Different false-positive rates HIV-1 were observed with Roche assays.

CONCLUSION

CVAs using DBS were useful for EID, although discrepant results were common. Further research is required to reduce false-positive results that could result in wrong diagnosis and unneeded treatment. We propose caution with low viral load (VL) values when using VL assays. Clear guidelines are required for EID of HIV-exposed infants with discrepant virological results.

Seesawed fluorescence nano-aptasensor based on highly vertical ZnO nanorods and three-dimensional quantitative fluorescence imaging for enhanced detection accuracy of ATP

Probe-mediated fluorescence biosensing methods based on spectrophotometry still have limitations such as detection inaccuracy caused by the occurrence of false signals and lack of simultaneous qualitative and quantitative read-outs with an ultra-low detection limit. Herein, we describe a novel seesawed fluorescence detection strategy based on dual-colour imaging-based quantitation in which the green fluorescence of the capture aptamer decreases and the red fluorescence of the detection aptamer increases simultaneously upon their respective interactions with the target biomolecule. This approach enhances detection accuracy through facilitating identification of probable false-positives in biological samples. Furthermore, combining the seesawed detection scheme with three-dimensional imaging of fluorescence signal enhanced by highly vertical ZnO nanorods increases signal-to-noise ratio, which addresses the limited performance of digital cameras and, in turn, enhances sensitivity and dynamic range. This simple, robust, scalable, imaging-based and label-free fluorescence method allows highly specific and sensitive quantification of biomolecules with excellent reliability.

Laboratory Evaluation of the Alere q Point-of-Care System for Early Infant HIV Diagnosis

Introduction

Early infant diagnosis (EID) and prompt linkage to care are critical to minimise the high morbidity and mortality associated with infant HIV infection. Attrition in the “EID cascade” is common; however, point-of-care (POC) EID assays with same-day result could facilitate prompt linkage of HIV-infected infant to treatment. Despite a number of POC EID assays in development, few have been independently evaluated and data on new technologies are urgently needed to inform policy.

Methods

We compared Alere q 1/2 Detect POC system laboratory test characteristics with the local standard of care (SOC), Roche CAP/CTM HIV-1 qualitative PCR in an independent laboratory-based evaluation in Cape Town, South Africa. Routinely EID samples collected between November 2013 and September 2014 were each tested by both SOC and POC systems. Repeat testing was done to troubleshoot any discrepancy between POC and SOC results.

Results

Overall, 1098 children with a median age of 47 days (IQR, 42–117) were included. Birth PCR (age <7 days) comprised of 8% (n = 92) tests while 56% (n = 620) of children tested as part of routine EID (ages 6–14 weeks). In the overall direct comparison, Alere q Detect achieved sensitivity of 95.5% (95% CI, 91.7–97.9%) and a specificity of 99.8% (95% CI, 99.1–100%). Following repeat testing of discordant samples and exclusion of any inconclusive results, the POC assay sensitivity and specificity were 96.9% (95% CI 93.4–98.9%) and 100% (lower 95% CI 98%) respectively. Among birth PCR tests the POC assay had slightly lower sensitivity (93.3% vs 96.5% in routine EID) and higher assay error rate (10% vs 5% in samples of older children, p = 0.04).

Conclusion

Our results indicate this POC assay performs well for EID in the laboratory. The high specificity and thus high positive predictive value would suggest a positive POC result may be adequate for immediate infant ART initiation. While POC testing for EID may have particular utility for birth testing at delivery facilities, the lower sensitivity and error rate requires further attention, as does field implementation of POC EID technologies in other clinical care settings.