National estimates and risk factors associated with early mother-to-child transmission of HIV after implementation of option B+: a cross-sectional analysis

Abstract

Background: Routine data from Malawi's prevention of mother-to-child transmission (MTCT) option B+ programme suggest high uptake of antiretroviral therapy (ART) among pregnant women. Malawi's Ministry of Health led the National Evaluation of Malawi's PMTCT Program to obtain nationally representative data on maternal ART coverage and prevention of MTCT effectiveness. Here, we present the early transmission data for infants aged 4-12 weeks.

Methods: We used a multistage cluster design to recruit a nationally representative sample of HIV-exposed infants and their mothers in Malawi. Between October 16, 2014, and May 17, 2016, we screened for HIV in all mothers attending an under-5 vaccination or outpatient sick-child clinic with infants aged 4-26 weeks at 54 health facilities selected across ten districts and four regional sampling zones. Infants with mothers identified as HIV-infected were enrolled in the cohort. We calculated weighted MTCT rates for only the subset of infants aged 4-12 weeks at screening, thereby capturing MTCT from early pregnancy, to delivery, and early breastfeeding. We collected data on maternal and infant demographics and self-reported use of HIV services, ART, and antenatal clinics. We tested HIV-exposed infants for the virus and assessed associations of certain variables with infant HIV status.

Findings: We confirmed HIV exposure in 3542 (10·4%) of 33 980 mother (guardian)-infant pairs with infants aged 4-26 weeks. Of those, 2530 (2514 mothers and 16 guardians) had infants aged 4-12 weeks at the time of screening (2498 singlets and 32 twins). We excluded 25 infants from the analysis because no information was available about their HIV status. 91·3% (95% CI 85·6-96·9) of mothers were on ART during pregnancy. The MTCT rate was 3·7% (2·3-6·0) overall and ranged from 1·4% (0·4-4·4) in women who initiated ART before pregnancy to 19·9% (13·4-28·6) in women not on ART. In multivariable logistic regression analysis, the odds of early MTCT were higher in mothers starting ART post partum (adjusted odds ratio 16·7, 95% CI 1·6-171·5; p=0·022) and in those not on ART with an unknown HIV status during pregnancy (19·1, 8·5-43·0; p<0·0001) than in mothers on ART before pregnancy. Among HIV-exposed infants, 98·0% (95% CI 96·9-99·1) were reported by the mother to have received infant nevirapine prophylaxis, and only 45·6% (34·8-56·4) were already enrolled in an exposed infant HIV care clinic at the time of study screening.

Interpretation: These data suggest that Malawi's decentralisation of ART services has resulted in higher ART coverage and lower early MTCT. However, the uptake of services for HIV-exposed infants remains suboptimal.

Funding: President's Emergency Plan for AIDS Relief.

Figure 1:. Directed acyclic graph of the hypothesised causal effect of mother’s reported timing of ART initiation on early transmission to infants aged 4–12 weeks

ANC=antenatal clinic. ART=antiretroviral therapy.

Figure 2:. Flow chart of mother-infant pair recruitment

MIP=mother (or guardian)–infant pairs.