An Early Infant HIV Risk Score for Targeted HIV Testing at Birth.

BACKGROUND: Early HIV testing is needed for treatment success in young infants, but universal testing is expensive. In this study, we examined the feasibility of early infant HIV risk scores for targeted polymerase chain reaction (PCR) testing and early HIV diagnosis.

METHODS: A cross-sectional cohort of newborns exposed to HIV was enrolled and PCR tested within 72 hours. We quantified associations between HIV infection and clinical and laboratory maternal-infant parameters by logistic regression models and determined sensitivity and specificity for derived risk scores.

RESULTS: From August 2014 to December 2016, 1759 participants were enrolled. Mothers without antenatal care (5.7% [97 of 1688]) were more likely to deliver newborns who are PCR-positive ( P = .0005). A total of 1 in 5 mothers (217 of 990; 21.9%) had HIV viral load (VL) >1000 copies per µL. A total of 432 of 1655 (26.1%) infants were preterm. Low birth weight was documented in 398 of 1598 (24.55%) and 13 of 31 (40.63%) newborns who are PCR-negative and -positive, respectively ( P = .0329). A total of 204 of 1689 (12.08%) were growth restricted or small for gestational age, and 6 of 37 (16.22%) were PCR-positive. Symptomatic newborns frequently tested positive ( P = .0042). The HIV PCR positivity rate was 2.2% (37 of 1703). Two-risk (combined 3-drug antiretroviral therapy [cART] duration, VL), 3-risk (cART duration, VL, symptomatic newborn), and 4-risk (cART duration, VL, symptomatic, small for gestational age newborn) models for HIV acquisition had predictive probability of 0.28, 0.498, and 0.57, respectively; this could guide targeted birth testing. However, using the 3- and 4-risk scores (probability 0.02 and 0.04), 20% and 24% will be missed compared with universal testing.

CONCLUSIONS: Targeted newborn testing requires access to maternal VL. Even if risk models include parameters such as maternal cART history, birth weight, weeks' gestation, and symptoms, 1 in 5 newborns who are infected will not be targeted. At present, we support universal PCR testing at birth within the South African prevention of mother-to-child transmission of HIV context.