Bringing early infant HIV diagnosis to the clinic

Accurate early infant HIV diagnosis in primary health clinics using a point-of-care nucleic acid test.

Jani IV, Meggi B, Mabunda N, Vubil A, Sitoe NE, Tobaiwa O, Quevedo JI, Lehe JD, Loquiha O, Vojnov L, Peter TF. J Acquir Immune Defic Syndr. 2014 Sep 1;67(1):e1-4. doi: 10.1097/QAI.0000000000000250

Objective: To evaluate the accuracy of a point-of-care (POC) nucleic acid-based test (NAT) for early infant HIV diagnosis (EID) in primary health clinics in Mozambique.

Methods: POC and laboratory NAT EID tests were conducted on matched blood samples collected from 827 HIV-exposed infants younger than 18 months who were enrolled consecutively at 4 periurban primary health clinics and the central hospital in Maputo. Lancet heel draw blood collected by nurses was tested on site for HIV-1/-2 RNA on the Alere HIV NAT POC device and also used to create dried blood spots for later laboratory EID testing on the Roche Cobas Taqman/Ampliprep instrument. Results were used to determine the sensitivity, specificity, and agreement between the POC and laboratory NAT EID tests.

Results: The sensitivity and specificity of POC NAT EID testing were 98.5% (95% confidence interval (CI): 91.7 to 99.9, n = 65) and 99.9% (95% CI: 99.3 to 100, n = 762), respectively, compared with laboratory EID tests. Overall agreement was high (Cohen kappa = 0.981; 95% CI: 0.96 to 1.00). Positive (98.5%; 95% CI: 96.3 to 100) and negative 99.9% (95% CI: 99.7 to 100) test agreement was also high.

Conclusions: Primary health care nurses accurately performed POC NAT EID testing within primary health care clinics. On-site nucleic acid-based EID testing is technically feasible in clinic settings and could be used in efforts to improve access to pediatric HIV antiretroviral treatment.

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Editor’s notes: World Health Organization (WHO) recommends immediate antiretroviral therapy (ART) for all infants and young children. However, only about a third of children living with HIV in resource-limited settings receive ART, primarily because of lack of access to early infant HIV diagnosis.

Currently, early infant diagnosis requires a laboratory infrastructure and trained technicians, which are complex and costly. Therefore early infant diagnosis is often centralized, requiring transport of samples and a long turnaround time of up to several months for HIV test results to be returned. This has a severe impact on retention in care of infants and on timely ART initiation.       

This study compared the diagnostic accuracy of two tests. These included a point-of-care nucleic acid-based HIV test to that of a conventional laboratory-based test for early infant diagnosis. The tests were administered to exposed infants in primary health care clinics in Mozambique. A heel-prick blood sample was used to conduct the point-of-care tests, with results available on the same day. The point-of-care test had very high sensitivity and specificity compared to the laboratory test, with a 99.8% agreement between the two testing platforms. In addition, the point-of-care test was successfully performed on-site, by non-laboratory personnel, clinic nurses.

 Mothers of the infants enrolled in the study had mainly received single-dose nevirapine or WHO Option A regimen, for prevention of vertical transmission. The study did not compare the performance of the point-of-care test in infants at birth or assess its reliability in infants who might be exposed to higher levels of ART. Nevertheless, this study demonstrates the feasibility of using point-of-care testing for early infant HIV diagnosis in decentralised and rural health care settings. While this will require strengthening of health system elements, point-of-care assays are likely to significantly reduce delay in diagnosis and increase access to ART among HIV-positive infants. 

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