Lifelong antiretroviral treatment for the prevention of mother-to-child transmission of HIV in routine healthcare in Tanzania, what works?

Sammanfattning: Background: The UNAIDS estimate of the risk of mother-to-child transmission of HIV (MTCT) in Tanzania remains unacceptably high at 11%, despite 84% coverage of lifelong antiretroviral treatment (ART) for the prevention of MTCT (PMTCT). ART is known to reduce MTCT to <2%, however its outcomes in routine healthcare have not been readily evaluated. This PhD thesis aimed to contribute knowledge on the outcomes of use of lifelong ART for PMTCT in routine healthcare in Dar es Salaam, Tanzania, and opportunities for improvement. Methods: Two prospective cohort studies were conducted to evaluate maternal and infant outcomes of lifelong ART for PMTCT. The studies involved 15,586 (study I) and 13,790 (study II) pregnant women who enrolled in routine PMTCT care between 2014 to 2017 and were followed up until 2021. Study outcomes were viral suppression [<400 viral copies/ mL] (study I) and MTCT [infant testing HIV positive by polymerase chain reaction or antibody test at ≥18 months old] (study II), and their determinants. Study III was a 1-year implementation study that evaluated the effect of engaging community leaders to improve male involvement in antenatal care (ANC) and couple HIV testing in six intervention facilities compared to 203 control facilities. Study IV was a cluster randomized implementation study involving 23 intervention and 24 control facilities to evaluate the effect of peer mother services in improving retention in care, viral suppression and MTCT among women on lifelong ART for PMTCT. Results: In study I, we observed 88.2% (95% CI: 87.8% to 88.7%) viral suppression among women on lifelong ART for PMTCT in routine care. Viral suppression improved on longer duration in care from 85.1% at 0-11 months to 90.6% at 36+ months since PMTCT enrolment. The risk of virologic failure was 76% higher in women aged <20 versus 30–39 years old; 28% higher in women starting PMTCT care in third versus first trimester; and 33% higher in women with advanced versus early stage HIV. Conversely, virologic failure was 19% lower among women at ANC clinics with high versus low couple HIV testing coverage. In study II we found a low MTCT risk of 1.8% (95% CI: 1.5% to 2.1%) by 18 months post-partum. The odds of MTCT were 2-3 times higher in women who started PMTCT care late in second/ third versus first trimester and twice as high in women with advanced versus early stage HIV. The odds of MTCT were 69% lower among women who started ART before pregnancy. In study III, the community-leaders intervention improved couple HIV testing from 11.9% to 36.0% (p <0.0001) at the intervention facilities compared to no change at the control facilities. In study IV, the peer-mother intervention, compared to control, resulted in significantly higher one-year ART retention (78.0% versus 73.6%) and higher viral suppression among ART naïve women at baseline (90.8% versus 88.1%). However, no significant difference was observed on MTCT. Conclusion: The findings of this thesis reaffirm the effectiveness of lifelong ART in achieving and sustaining high (>90%) maternal viral suppression and low (<2%) risk of MTCT in routine healthcare. The findings indicate that adolescent mothers, late care seekers and women with advanced HIV remain vulnerable to poor outcomes. The findings also highlight need for and opportunities to strengthen male involvement and peer mother engagement to further improve outcomes of lifelong ART for PMTCT in routine healthcare.