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Point-Of-Care p24 Infant Testing for HIV May Increase Patient Identification despite Low Sensitivity
Bindiya Meggi1, Timothy Bollinger2, Nédio Mabunda1
1Instituto Nacional de Saúde, Maputo, Mozambique.
Insights
Point-of-care (POC) HIV testing for infants in Mozambique showed potential for faster results, improving early diagnosis and linkage to antiretroviral treatment (ART). While sensitivity was lower than lab tests, POC EID platforms can enhance patient follow-up in resource-limited settings.
Area of Science:
- Medical Diagnostics
- Infectious Disease Research
- Public Health
Background:
- Delays in early infant diagnosis (EID) of HIV (EID) and subsequent antiretroviral treatment (ART) initiation lead to loss-to-follow-up in resource-limited settings.
- Point-of-care (POC) testing offers a potential solution to expedite diagnosis and treatment initiation.
Purpose of the Study:
- To evaluate the performance of the LYNX p24 Antigen POC test for early infant diagnosis of HIV in Mozambique.
- To compare the effectiveness of POC testing versus laboratory-based testing in ensuring timely diagnosis and linkage to care.
Main Methods:
- 879 HIV-exposed infants (<18 months) were enrolled in three primary healthcare clinics (PHCs) in Mozambique.
- Lancet heel-drawn blood samples were tested on-site using a prototype POC HIV Gag p24 antigen assay.
- POC test results were compared against laboratory-based nucleic acid testing on dried blood spots.
Main Results:
- The LYNX p24 Ag POC test demonstrated a sensitivity of 71.9% and specificity of 99.6%.
- Positive and negative predictive values were 93.2% and 97.9%, respectively, with high overall agreement (Cohen Kappa = 0.80).
- Despite lower sensitivity, the POC test could potentially reach 81% more patients with timely results compared to laboratory testing.
Conclusions:
- The prototype POC p24 assay is feasible for use in PHCs but exhibits suboptimal sensitivity for HIV detection.
- POC EID technologies, even with performance below standard recommendations, can be valuable tools in settings with inefficient EID networks.
- POC testing significantly improves the potential for timely diagnosis and follow-up for HIV-exposed infants.
Abstract:
The long delay in returning test results during early infant diagnosis of HIV (EID) often causes loss-to-follow-up prior to antiretroviral treatment (ART) initiation in resource-limited settings. A point-of-care (POC) test may help overcome these challenges. We evaluated the performance of the LYNX p24 Antigen POC test in Mozambique. 879 HIV-exposed infants under 18 months of age were enrolled consecutively at three primary healthcare clinics (PHC). Lancet heel-drawn blood was tested on-site by nurses using a prototype POC test for HIV Gag p24 antigen detection. Results of POC testing were compared to laboratory-based nucleic acid testing on dried blood spots. A comparison of the effect of sensitivity and timely test results return on successful diagnosis by POC and laboratory-based platforms was also calculated. The sensitivity and specificity of the LYNX p24 Ag test were 71.9%; (95% confidence interval [CI]: 58.5-83.0%) and 99.6% (95% CI: 98.9-99.9%), respectively. The predictive value of positive and negative tests were 93.2% (95% CI: 81.3-98.6%) and 97.9% (95% CI: 96.8-98.8%), respectively. Overall agreement was high (Cohen Kappa = 0.80; 95% CI: 0.71-0.89). Despite its lower sensitivity, the POC test had the potential to provide test results to up to 81% more patients compared to the laboratory-based test. This prototype POC p24 assay was feasible for use in PHCs but demonstrated low sensitivity for HIV detection. POC EID technologies that perform below standard recommendations may still be valuable diagnostic tools in settings with inefficient EID networks.
