Evaluation of the Population-level Impact of PMTCT Option B+ Implemented in Zimbabwe

Sponsor: University of California Berkeley

Location(s): Zimbabwe


Option B+ is an intervention for the prevention of mother-to-child transmission of HIV that is expected to reduce the number of infants who are infected with HIV and help keep their HIV-infected mothers alive, although the current evidence for this is weak. We aim to assess if these expected results are observed in reality, based on data we will collect in Zimbabwe. Our results will help us understand whether Option B+ has the intended impact of reducing the number of HIV transmissions to infants, of keeping infants alive longer, and of maintaining mothers on antiretroviral treatment after they finish breastfeeding. Our study will also determine whether the intervention's additional costs over previous interventions are in line with the benefits.

Although Option B+ is being rolled out in many developing countries for the prevention of mother-to-child HIV transmission (PMTCT), robust evidence of its population-level effectiveness and cost-effectiveness is currently lacking. This is complicated by the fact that the impact of Option B+ may vary according to whether PMTCT and antiretroviral therapy (ART) services are already successfully integrated in health facilities. A population- level effectiveness study would determine the HIV-free survival rate and/or the mother-to-child transmission of HIV (MTCT) rate among the entire community of infants and not just among those whose mothers accessed PMTCT services. Another outstanding issue is the extent to which it will be possible to retain women on lifelong ART, especially those who start ART during pregnancy and who are asymptomatic. Our proposed study will fill these research gaps using representative community-level serosurvey data from Zimbabwe. In 2012 our team conducted a community survey of over 9,000 mother-infant pairs that were born before the implementation of Option A in Zimbabwe;preliminary results revealed that HIV prevalence among mothers was 12.5% and MTCT was 9% among infants aged 9-18 months. Between October 2013 and September 2014, Zimbabwe will roll out Option B+, requiring integration of PMTCT and ART services in all 1,560 facilities. In 2014, we will conduct a post-Option A / pre-Option B+ survey of 10,000 mother-infant pairs using methodology similar to that of our 2012 survey. In 2017 we will survey 13,000 mother-infant pairs and will assess the impact of Option B+ using two strategies.
Aim 1a. Compare outcomes from 2017 versus 2012, permitting a comparison of Option B+ to the standard of care prior to the implementation of Option A.
Aim 1b. compare outcomes from 2017 to those from 2014, permitting a direct assessment of the value- added of Option B+ over Option A.
Notably, HIV-free survival among HIV-exposed infants takes into account both HIV-infection and mortality, which is critical given the high mortality rates experienced by HIV- exposed and HIV-infected infants. By focusing on infants born 9-18 months prior to the surveys we capture transmissions occurring during pregnancy, labor and breastfeeding.
Aim 2. Examine impact heterogeneity by the level of integration of PMTCT and ART services at the facility and other facility characteristics.
Aim 3. The 2017 community-based survey will also include 1,800 mothers of 19-36 months old infants, to assess HIV-infected mothers'retention in ART services after weaning.
Aim 4. In addition to household-level data, we will collect comprehensive facility-level data to assess cost- effectiveness of Option B+.
Our results will have direct relevance for Zimbabwe and other developing countries, as they will inform evidence-based decisions for Ministries of Health that are considering Option B+, irrespective of whether they implemented previous WHO guidelines including Option A.