The National Evaluation of Malawi's PMTCT Program (NEMAPP) study: 24-month HIV-exposed infant outcomes from a prospective cohort study

Abstract

Objectives: Data on long-term HIV-free survival in breastfeeding, HIV-exposed infants (HEIs) are limited. The National Evaluation of Malawi's Prevention of Mother-to-Child Transmission (PMTCT) Program (NEMAPP), conducted between 2014 and 2018, evaluated mother-to-child transmission (MTCT) and infant outcomes up to 24 months postpartum.

Methods: We enrolled a nationally representative cohort of HEIs at 54 health facilities across four regional strata in Malawi and used multivariable Cox regression analysis to investigate the risk of adverse outcomes (HIV transmission, infant death and loss to follow-up) to 24 months postpartum. Models, controlling for survey design, were fitted for the total cohort (n = 3462) and for a subcohort that received maternal viral load (VL) monitoring (n = 1282).

Results: By 24 months, in 3462 HEIs, weighted cumulative MTCT was 4.9% [95% confidence interval (CI) 3.7-6.4%], 1.3% (95% CI 0.8-2.2%) of HEIs had died, 26.2% (95% CI 24.0-28.6%) had been lost to follow-up and 67.5% (95% CI 65.0-70.0%) were alive and HIV-free. Primiparity [weighted adjusted hazard ratio (aHR) 1.6; 95% CI 1.1-2.2; parity 2-3: weighted aHR 1.5; 95% CI 1.2-1.9], the mother not disclosing her HIV status to her partner (no disclosure: weighted aHR 1.3; 95% CI 1.1-1.6; no partner: weighted aHR 0.7; 95% CI 0.5-0.9), unknown maternal ART start (weighted aHR 2.0; 95% CI 1.0-3.9) and poor adherence (missed ≥ 2 days of ART in the last month: weighted aHR 1.7; 95% CI 1.2-2.2; not on ART: weighted aHR 1.7; 95% CI 1.0-2.7) were associated with adverse outcomes by 24 months. In the subcohort analysis, risk of HIV transmission or infant death was higher among HEIs whose mothers started ART post-conception (during pregnancy: weighted aHR 3.2; 95% CI 1.3-7.7; postpartum: weighted aHR 12.4; 95% CI 1.5-99.6) or when maternal viral load at enrolment was > 1000 HIV-1 RNA copies/mL (weighted aHR 15.7; 95% CI 7.8-31.3).

Conclusions: Infant positivity and infant mortality at 24 months were low for a breastfeeding population. Starting ART pre-conception had the greatest impact on HIV-free survival in HEIs. Further population-level reduction in MTCT may require additional intervention during breastfeeding for women new to PMTCT programmes. Pre-partum diagnosis and linkage to ART, followed by continuous engagement in care during breastfeeding can further reduce MTCT but are challenging to implement.

Keywords: HIV-exposed infants; HIV-free survival; Malawi; Option B+; disclosure; mother-infant pairs; prevention of mother-to-child transmission; treat all.