Performance of Virological Testing for Early Infant Diagnosis

A Systematic Review

Divya Mallampati, MD, MPH; Nathan Ford, MPH, PhD, FRCPE; Alisse Hanaford, BS; Nandita Sugandhi, MD; Martina Penazzato, MD, PhD

Disclosures

J Acquir Immune Defic Syndr. 2017;75(3):308-314. 

In This Article

Abstract and Introduction

Abstract

Background: Improved access to both maternal antiretroviral therapy and infant prophylaxis may have an impact on the performance of virological assays for diagnosis of HIV infection in infants. This systematic review was performed to assess the diagnostic accuracy of virological testing at birth as well as the performance of virological testing on dried blood spots at 6 weeks among HIV- and antiretroviral (ARV)-exposed infants.

Methods: A systematic review was performed for studies published between January 1, 2009 and January 30, 2015. The search strategy included studies related to HIV, nucleic acid amplification tests, and newborns/infants and queried PubMed, Embase, the Cochrane Library, LILACS as well as several conference proceedings. Two independent reviewers collected studies and extracted data. The final analysis includes summary estimates of the sensitivities and specificities of the virological assays assessed. The GRADE approach was used to assess the overall quality of evidence and Quality Assessment of Diagnostic Accuracy Studies was used to evaluate the risk of bias in the studies.

Results: A total of 2243 records were screened with a final selection of 5 manuscripts. To assess the test characteristics of virological testing at birth, 2 studies were used to calculate a pooled sensitivity of 69.3% (95% confidence interval: 61.1 to 77.4) and a specificity of 99.9% (98.6–100%). The quality of evidence to support the sensitivity of assays at birth was low, whereas the quality of evidence for the specificity of such tests was intermediate-high. In terms of the performance of virological testing on dried blood spots for HIV- and ARV-exposed infants, 3 studies were used to calculate a pooled sensitivity of 99.4% (98.3–100.00%) and specificity of 99.6% (99.1–100.00%). The quality of evidence for both outcomes was low.

Conclusion: The performance of polymerase chain reaction at birth demonstrates low sensitivity and high specificity, reflecting the difficulty of detecting intrapartum infections at birth and transmission dynamics. In addition, there is no evidence to suggest poor performance of virological testing on dried blood spots for ARV-exposed infants. Overall, given the very limited and low-quality evidence, further research is needed to assess the accuracy of polymerase chain reaction at different time points and in the context of more effective prevention of mother-to-child transmission interventions.

Introduction

Despite the expansion of prevention of mother-to-child transmission programs and the reduction in absolute numbers of new infections, only an estimated 50%[1] of HIV-exposed infants are tested within the first 2 months of life. Published literature suggests that approximately 40% of those tested are linked to care and only 30% are subsequently started on antiretroviral therapy (ART).[2] Overall, treatment coverage for children with HIV is much lower than for pregnant women, with other estimates indicating that only 51% of children in need receive ART compared with 74% of pregnant women.[3] More efforts are needed to ensure that infants and children are timely identified and adequately linked to care to rapidly start antiretroviral (ARV) treatment.

The timing of infection influences mortality rates for infants with HIV. In infants who acquire HIV in utero or intrapartum, disease progression is more rapid than those who acquire HIV through breastfeeding.[4] A recent analysis predicted that in the absence of treatment, the net survival at 1 year for infants infected perinatally was 52%, whereas those infected through breastfeeding was 78%.[5] Diagnosing HIV infection and initiating ART in the first few months after infection can reduce mortality by 76%,[6] and the World Health Organization (WHO) recommends starting therapy as soon as infants are diagnosed with HIV.[7]

Current WHO guidelines recommend that HIV-exposed infants receive virological testing between 4 and 6 weeks of age.[8] Ultimately, the timing of testing needs to optimize the performance characteristics of virological assays used while minimizing delays that can result in patient attrition between sample collection and receipt of result. At the recommended 4–6 weeks, virological testing can detect in utero infections and nearly all intrapartum infections.[1]

Given the high rates of mortality, detecting infants who have been infected in utero or intrapartum can have significant benefits. Some data suggest that 80% of infections detectable at 4–6 weeks are also detectable at birth,[9] but these birth tests have limited sensitivity for the detection of HIV at early ages.[10] There is little evidence on the performance of virological testing at birth in the setting of maternal ARV use or postnatal prophylaxis.

While both whole blood and dried blood spots (DBS) can be used as samples for early infant diagnosis, there are significant advantages to using DBS, particularly in resource-limited settings.[1] However, the impact of maternal ARV regimens to prevent mother-to-child transmission on the performance of DBS specimens is unclear. Several studies exist assessing good performance of DBS,[11–15] but these data have not been systematically assessed.

We conducted this systematic review to inform the revision of WHO 2016 Consolidated Guidelines for the Use of Antiretroviral Drugs for Treatment and Prevention of HIV. We assessed the use of DBS in the context of maternal ARV use at 4–6 weeks of life and the performance characteristics of polymerase chain reaction (PCR) test at birth to diagnose HIV.

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