Discrepant test findings in early infant diagnosis of HIV in a national reference laboratory in Kenya: challenges and opportunities for programs

Evolution of prevention of vertical HIV transmission in Uganda: 2008–2017

OBJECTIVES

Uganda adapted its policy for prevention of vertical transmission (VT) of HIV transmission as the World Health Organization released Options A, B and B+. We assessed trends in diagnostic testing, breastfeeding practices, maternal and infant antiretroviral therapy (ART), mortality, VT and HIV-free survival (HFS) among Ugandan infants born to women living with HIV during this period of successive guideline changes.

METHODS

This is is a retrospective observational study of infants attending early infant diagnosis clinics at two Ugandan hospitals.

RESULTS

A total of 1885 infants (48% female) were managed from 2009 to 2017. DNA polymerase chain reaction (PCR) for early infant diagnosis was performed on 1719 infants (92%, one or more PCR tests) and 676 infants (36%, two PCR tests). HIV serology was performed on 90 infants (4.8%). Testing increased over the study period but remained suboptimal, due to high loss to follow-up (LTFU). A total of 93% of infants were breastfed, for a median of 9.5 months. The duration of breast milk exposure increased over the study period, consistent with guidelines that increasingly encouraged breastfeeding. Nine cases (0.48%) of suspected breast milk transmission were observed. The use of ART increased significantly over the study period. Mortality (3.5%, 2.7% and 1.1%; p = 0.0076) and VT (17%, 12% and 7.4%; p < 0.0001) decreased over the study period (2008-2010, 2011-2012 and 2013-2017, respectively). LTFU values were 31%, 49% and 59% at 6, 12 and 18 months of age, respectively, with only modest improvements over time. HFS could only be conclusively documented in 532 infants (28%) because of LTFU.

CONCLUSIONS

From 2009 to 2017, outcomes improved among HIV-exposed infants in Uganda. LTFU remains a barrier to optimal care.

HIV diagnostic algorithm requires confirmatory testing for initial indeterminate or positive screens in the first week of life

BACKGROUND

Risk for nondiagnostic and false-positive HIV testing has not been quantified for neonates.

METHODS

From April 2015 to July 2018, we screened HIV-exposed infants in Botswana less than 96 h from birth by qualitative DNA PCR. Repeat blood draws for DNA and RNA PCR testing occurred for initial positive and indeterminate results to establish final diagnosis. We compared screening DNA PCR cycle threshold values with final HIV status of the child.

RESULTS

Of 10 622 HIV-exposed infants, 10 549 (99.3%) had no HIV DNA detected (negative), 42 (0.4%) had HIV DNA detected (positive), and 31 (0.3%) tested indeterminate at first HIV screen. Repeat testing identified 2 (5.0%) of 40 positive screens (2 declined additional testing) as false positives and confirmed 2 (6.5%) of 31 indeterminate screens as infected. Median cycle threshold value at screening was 28.1 (IQR 19.8--34.8) for children with final positive status, and 35.5 (IQR 32.8--41.4) for indeterminates who were ultimately negative. Six (15%) of 40 infants with final positive status had cycle threshold value greater than 33 at first screen, whereas 3 (9.7%) of 31 indeterminates with final negative status had cycle threshold value 33 or less at first screen. This threshold resulted in a negative predictive value of 82% and a positive predictive value of 92% for a single screen.

CONCLUSION

Although a DNA PCR cycle threshold value of 33 was predictive of the final HIV status in newborns, overlap occurred for true positives, false positives, and initial indeterminates. Testing additional samples should be standard practice for positive and indeterminate HIV DNA PCR tests in the first week of life.

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.

Viral load assay performs comparably to early infant diagnosis assay to diagnose infants with HIV in Mozambique: a prospective observational study

INTRODUCTION

Viral load testing is essential to manage HIV disease, especially in infants and children. Early infant diagnosis is performed using nucleic-acid testing in children under 18 months. Resource-limited health systems face severe challenges to scale-up both viral load and early infant diagnosis to unprecedented levels. Streamlining laboratory systems would be beneficial to improve access to quality testing and to increase efficiency of antiretroviral treatment programmes. We evaluated the performance of viral load testing to serve as an early infant diagnosis assay in children younger than 18 months.

METHODS

This study was an observational, prospective study, including children between one and 18 months of age who were born to HIV-positive mothers in 134 health facilities in Maputo City and Maputo Province, Mozambique. Dried blood spot specimens from heel or toe pricks were collected between January and April 2018, processed using SPEX buffer for both assays, and tested for routine EID and VL testing using the Roche CAP/CTM HIV-1 Qualitative v2 and Roche CAP/CTM HIV-1 Quantitative v2 assays respectively. The sensitivity, specificity and positive and negative predictive values were estimated using the EID results as the reference standard.

RESULTS

A total of 1021 infants were included in the study, of which 47% were female. Over 95% of mothers and children were on antiretroviral treatment or received antiretroviral prophylaxis respectively. The sensitivity and specificity of using the viral load assay to detect infection were 100% (95% CI: 96.2 to 100%) and 99.9% (95% CI: 99.4 to 100%). The positive and negative predictive values were 99.0% (95% CI: 94.3 to 100%) and 100% (95% CI: 99.6 to 100%). The McNemar's test was 1.000 and Cohen's kappa was 0.994.

CONCLUSIONS

The comparable performance suggests that viral load assays can be used as an infant diagnostic assay. Infants with either low levels of viraemia or high cycle threshold values should be repeat tested to ensure the result is truly positive prior to treatment initiation, regardless of assay used. Viral load assays could replace traditional early infant diagnosis testing, substantially streamlining molecular laboratory services for children and lowering costs, with the additional advantage of providing baseline viral load results for antiretroviral treatment management.

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.

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

Background

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

Objective

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

Methods

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

Results

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

Conclusion

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

Field evaluation of HIV point-of-care testing for early infant diagnosis in Cape Town, South Africa

Background

Early infant HIV diagnosis (EID) coverage and uptake remains challenging. Point-of-care (POC) testing may improve access and turn-around-times, but, while several POC technologies are in development there are few data on their implementation in the field.

Methods

We conducted an implementation study of the Alere q Detect POC system for EID at two public sector health facilities in Cape Town. HIV-exposed neonates undergoing routine EID testing at a large maternity hospital and a primary care clinic received both laboratory-based HIV PCR testing per local protocols and a POC test. We analysed the performance of POC versus laboratory testing, and conducted semi-structured interviews with providers to assess acceptability and implementation issues.

Results

Overall 478 specimens were taken: 311 tests were performed at the obstetric hospital (median child age, 1 days) and 167 six-week tests in primary care (median child age, 42 days). 9.0% of all tests resulted in an error with no differences by site; most errors resolved with retesting. POC was more sensitive (100%; lower 95% CI, 39.8%) and specific (100%, lower 95% CI, 98%) among older children tested in primary care compared with birth testing in hospital (90.0%, 95% CI, 55.5–99.8% and 100.0%, lower 95% CI, 98.4%, respectively). Negative predictive value was high (>99%) at both sites. In interviews, providers felt the device was simple to use and facilitated decision-making in the management of infants. However, many wanted clarity on the cause of errors on the POC device to help guide repeat testing.

Conclusions

POC EID testing performs well in field implementation in health care facilities and appears highly acceptable to health care providers.

The value of confirmatory testing in early infant HIV diagnosis programmes in South Africa: A cost-effectiveness analysis

BACKGROUND

The specificity of nucleic acid amplification tests (NAATs) used for early infant diagnosis (EID) of HIV infection is <100%, leading some HIV-uninfected infants to be incorrectly identified as HIV-infected. The World Health Organization recommends that infants undergo a second NAAT to confirm any positive test result, but implementation is limited. Our objective was to determine the impact and cost-effectiveness of confirmatory HIV testing for EID programmes in South Africa.

METHOD AND FINDINGS

Using the Cost-effectiveness of Preventing AIDS Complications (CEPAC)-Pediatric model, we simulated EID testing at age 6 weeks for HIV-exposed infants without and with confirmatory testing. We assumed a NAAT cost of US$25, NAAT specificity of 99.6%, NAAT sensitivity of 100% for infants infected in pregnancy or at least 4 weeks prior to testing, and a mother-to-child transmission (MTCT) rate at 12 months of 4.9%; we simulated guideline-concordant rates of testing uptake, result return, and antiretroviral therapy (ART) initiation (100%). After diagnosis, infants were linked to and retained in care for 10 years (false-positive) or lifelong (true-positive). All parameters were varied widely in sensitivity analyses. Outcomes included number of infants with false-positive diagnoses linked to ART per 1,000 ART initiations, life expectancy (LE, in years) and per-person lifetime HIV-related healthcare costs. Both without and with confirmatory testing, LE was 26.2 years for HIV-infected infants and 61.4 years for all HIV-exposed infants; clinical outcomes for truly infected infants did not differ by strategy. Without confirmatory testing, 128/1,000 ART initiations were false-positive diagnoses; with confirmatory testing, 1/1,000 ART initiations were false-positive diagnoses. Because confirmatory testing averted costly HIV care and ART in truly HIV-uninfected infants, it was cost-saving: total cost US$1,790/infant tested, compared to US$1,830/infant tested without confirmatory testing. Confirmatory testing remained cost-saving unless NAAT cost exceeded US$400 or the HIV-uninfected status of infants incorrectly identified as infected was ascertained and ART stopped within 3 months of starting. Limitations include uncertainty in the data used in the model, which we examined with sensitivity and uncertainty analyses. We also excluded clinical harms to HIV-uninfected infants incorrectly treated with ART after false-positive diagnosis (e.g., medication toxicities); including these outcomes would further increase the value of confirmatory testing.

CONCLUSIONS

Without confirmatory testing, in settings with MTCT rates similar to that of South Africa, more than 10% of infants who initiate ART may reflect false-positive diagnoses. Confirmatory testing prevents inappropriate HIV diagnosis, is cost-saving, and should be adopted in all EID programmes.

Mother-to-child transmission of HIV in Kenya: A cross-sectional analysis of the national database over nine years

Objective

To describe factors associated with mother-to-child HIV transmission (MTCT) in Kenya and identify opportunities to increase testing/care coverage.

Design

Cross-sectional analysis of national early infant diagnosis (EID) database.

Methods

365,841 Kenyan infants were tested for HIV from January 2007-July 2015 and results, demographics, and treatment information were entered into a national database. HIV risk factors were assessed using multivariable logistic regression.

Results

11.1% of infants tested HIV positive in 2007–2010 and 6.9% in 2014–2015. Greater odds of infection were observed in females (OR: 1.08; 95% CI:1.05–1.11), older children (18–24 months vs. 6 weeks-2 months: 4.26; 95% CI:3.87–4.69), infants whose mothers received no PMTCT intervention (vs. HAART OR: 1.92; 95% CI:1.79–2.06), infants receiving no prophylaxis (vs. nevirapine for 6 weeks OR: 2.76; 95% CI:2.51–3.05), and infants mixed breastfed (vs. exclusive breastfeeding OR: 1.39; 95% CI:1.30–1.49). In 2014–2015, 9.1% of infants had mothers who were not on treatment during pregnancy, 9.8% were not on prophylaxis, and 7.0% were mixed breastfed. Infants exposed to all three risky practices had a seven-fold higher odds of HIV infection compared to those exposed to recommended practices. The highest yield of HIV-positive infants were found through targeted testing of symptomatic infants in pediatric/outpatient departments (>15%); still, most infected infants were identified through PMTCT programs.

Conclusion

Despite impressive gains in Kenya’s PMTCT program, some HIV-infected infants present late and are not benefitting from PMTCT best practices. Efforts to identify these early and enforce evidence-based practice for PMTCT should be scaled up. Infant testing should be expanded in pediatric/outpatient departments, given high yields in these portals.

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.

Performance of Roche CAP/CTM HIV-1 qualitative test version 2.0 using dried blood spots for early infant diagnosis

In the context of early infant diagnosis (EID) decentralization in sub-Saharan Africa, dried blood spot (DBS) is now widely used for HIV proviral DNA detection in resource-limited settings. A new version of CAP/CTM (version 2) has been introduced, recently by Roche Diagnosis as a new real-time PCR assay to replace previous technologies on qualitative detection of HIV-1 DNA using whole blood and DBS samples. The objective of this study was to evaluate CAP/CTM version 2 compared to CAP/CTM version 1 and Amplicor on DBS. A total of 261 DBS were collected from children aged 4 weeks to 17 months born from HIV-seropositive mothers and tested by the three techniques. CAP/CTM version 2 showed 100% of agreement with Amplicor including 74 positive results and 187 negative results. CAP/CTM version 2 versus CAP/CTM version 1 as well as CAP/CTM version 1 versus Amplicor showed two discordant results giving a sensitivity of 98.6%, specificity of 99.5%, positive predictive value of 98.6% and negative predictive value of 99.5%. The concordance was 99.12% (95% of confidence interval) giving a Kappa coefficient of 0.97 (p<0.001). These findings confirmed the expected good performance of CAP/CTM version 2 for HIV-1 EID.

Performance of an Early Infant Diagnostic Test, AmpliSens DNA-HIV-FRT, Using Dried Blood Spots Collected from Children Born to Human Immunodeficiency Virus-Infected Mothers in Ukraine

An accurate accessible test for early infant diagnosis (EID) is crucial for identifying HIV-infected infants and linking them to treatment. To improve EID services in Ukraine, dried blood spot (DBS) samples obtained from 237 HIV-exposed children (≤18 months of age) in six regions in Ukraine in 2012 to 2013 were tested with the AmpliSens DNA-HIV-FRT assay, the Roche COBAS AmpliPrep/COBAS TaqMan (CAP/CTM) HIV-1 Qual test, and the Abbott RealTime HIV-1 Qualitative assay. In comparison with the paired whole-blood results generated from AmpliSens testing at the oblast HIV reference laboratories in Ukraine, the sensitivity was 0.99 (95% confidence interval [CI], 0.95 to 1.00) for the AmpliSens and Roche CAP/CTM Qual assays and 0.96 (95% CI, 0.90 to 0.98) for the Abbott Qualitative assay. The specificity was 1.00 (95% CI, 0.97 to 1.00) for the AmpliSens and Abbott Qualitative assays and 0.99 (95% CI, 0.96 to 1.00) for the Roche CAP/CTM Qual assay. McNemar analysis indicated that the proportions of positive results for the tests were not significantly different (P > 0.05). Cohen's kappa (0.97 to 0.99) indicated almost perfect agreement among the three tests. These results indicated that the AmpliSens DBS and whole-blood tests performed equally well and were comparable to the two commercially available EID tests. More importantly, the performance characteristics of the AmpliSens DBS test meets the World Health Organization EID test requirements; implementing AmpliSens DBS testing might improve EID services in resource-limited settings.

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

This report summarizes 2 children misdiagnosed with HIV infection in a clinic in rural Zambia and discusses the implications of false-positive HIV DNA tests in HIV-exposed infants, including the potential magnitude of the problem. Recommendations are needed to address the management of children receiving antiretroviral therapy who are suspected of being uninfected.

Field evaluation of Abbott Real Time HIV-1 Qualitative test for early infant diagnosis using dried blood spots samples in comparison to Roche COBAS Ampliprep/COBAS TaqMan HIV-1 Qual test in Kenya

Timely diagnosis and treatment of infants infected with HIV are critical for reducing infant mortality. High-throughput automated diagnostic tests like Roche COBAS AmpliPrep/COBAS TaqMan HIV-1 Qual Test (Roche CAPCTM Qual) and the Abbott Real Time HIV-1 Qualitative (Abbott Qualitative) can be used to rapidly expand early infant diagnosis testing services. In this study, the performance characteristics of the Abbott Qualitative were evaluated using two hundred dried blood spots (DBS) samples (100 HIV-1 positive and 100 HIV-1 negative) collected from infants attending the antenatal facilities in Kisumu, Kenya. The Abbott Qualitative results were compared to the diagnostic testing completed using the Roche CAPCTM Qual in Kenya. The sensitivity and specificity of the Abbott Qualitative were 99.0% (95% CI: 95.0-100.0) and 100.0% (95% CI: 96.0-100.0), respectively, and the overall reproducibility was 98.0% (95% CI: 86.0-100.0). The limits of detection for the Abbott Qualitative and Roche CAPCTM Qual were 56.5 and 6.9copies/mL at 95% CIs (p=0.005), respectively. The study findings demonstrate that the Abbott Qualitative test is a practical option for timely diagnosis of HIV in infants.