Six years after pregnancy, almost half of women with HIV in Tanzania have dropped out of care

Long-term retention in HIV care is a challenge for vertical transmission prevention in African countries, new data show. Among pregnant women with HIV who enrolled for vertical transmission prevention services in Tanzania, only 78% remained in the programme after the first year. By the sixth year, only 56% were still receiving HIV care.

According to the study by researchers from the Tanzanian non-profit organisation Management and Development for Health, nearly 50% of the women who discontinued in the first year did so after only one visit and never returned. Furthermore, treatment discontinuation was higher among younger women. By the end of the six-year follow-up period, only 36% of those under 20 were still receiving antiretroviral therapy (ART) care, compared to 50%, 60%, and 67% of women aged 20–29, 30–39, and 40 years and older, respectively.

In 2021, there were almost two million Tanzanians living with HIV, with 59% of them being women of reproductive age (15–49 years). Although lifelong ART for women during and after pregnancy has been found to reduce the vertical HIV transmission risk to less than 5% in breastfeeding populations, Tanzania’s vertical transmission rate remains high at 11%.

In Tanzania, all pregnant women diagnosed with HIV are enrolled in vertical transmission prevention services which provide antenatal care, ART and infant testing. Peer mothers provide psychosocial support and remind the women of their clinic appointments and infant testing dates. Two years after birth, upon receipt of final infant HIV test results or earlier if the infant was diagnosed with HIV, women are discharged to general HIV clinics to continue HIV care.

The researchers, therefore, investigated long-term retention and attrition (loss to follow-up, stopping ART or death) in ART care among women with HIV up to six years after enrolment in vertical transmission prevention services in health facilities in the country’s largest city, Dar es Salaam.

A total of 22,631 participants were identified across 226 public and private health facilities. The study included women who were diagnosed with HIV either before or during pregnancy and were enrolled in ART and vertical prevention services between 2015 and 2017. They were followed for a median of three years and for a maximum of six years.

Participants’ mean age at enrolment was 30 years. Slightly over half (52%) were married or cohabiting and most (82%) were enrolled in vertical transmission prevention services late (second or third trimester of pregnancy). About one-third (37%) had been diagnosed with HIV and initiated ART prior to enrolment in the study, while 26% had advanced HIV disease.

Results

A total of 7714 ART discontinuations were observed during 55,732 person-years of follow-up. The vast majority were women who were lost to follow up, although 176 were known to have stopped treatment and 363 women died.

• The overall attrition rate was 13.8 per 100 person-years.
• Over half of the discontinuations (57%) occurred during the first year, which had the highest attrition rate: 27.1 per 100 person-years.
• The largest group of first-year attritions (47%) were women who made only one visit and never returned.
• At the end of the first year of follow-up, 78% of women were retained in care.
• After that, the proportion remaining in care declined to 69%, 63%, 60%, 57% and 56% at two, three, four, five and six years.

There were several predictors of ART attrition:

• Age: Adolescents under 20 had a 63% higher attrition rate (adjusted hazard ratio 1.63) than 30–39 year-old women.
• Gestation age at enrolment: Only 53% of women enrolled for vertical transmission prevention services in their third trimester remained in care, compared to 57% in their second trimester and 62% in their first trimester.
• Repeated pregnancy: Women who had a repeated pregnancy during the follow-up period had a 35% lower attrition rate (aHR 0.65) than those who did not.
• Time on ART: Women who started ART before pregnancy had a 31% lower attrition rate (aHR 0.69, 95% C1: 0.54–0.59) than those who started during pregnancy.
• Advanced HIV: Women who had advanced HIV disease had a 12% lower attrition rate (aHR 0.88, 95% CI: 0.81–0.93) than those without.
• Type of facility: Attrition was 16% lower among women receiving care in higher-level health centres (aHR 0.84) than in lower-level dispensaries.

Vertical transmission in South Africa

The high attrition rate, especially in the first year of enrolment, poses a great challenge in ending vertical transmission. This is supported by a South African study, which found that out of 50,461 infants born between 2018 and 2021 to mothers known to have HIV at the time of delivery, 894 infants (2%) were diagnosed with HIV.

Among these infants, 43% were diagnosed within a week of birth (suggesting transmission during pregnancy), 16% were diagnosed within 1 and 14 weeks of birth (suggesting transmission during delivery or in the early stages of breastfeeding) and 41% were diagnosed after 14 weeks (suggesting transmission through breastfeeding).

The study found a strong link between vertical transmission and recent high maternal viral load, with a seven-fold increase in transmission even with slightly elevated viral load of between 100 and 999 copies/ml, compared to a viral load below 100 copies/ml.

Vertical transmission was also associated with the mother being under 20 years, a low CD4 count, not receiving ART during pregnancy, starting ART late in pregnancy, restarting ART in pregnancy and gaps in ART coverage.

“Mothers who transmit HIV to their infants in the era of universal maternal ART represent a vulnerable population who require improved access to care and enhanced social and adherence support,” say the researchers. To close the gaps they recommend identifying and supporting mothers-at-risk and helping pregnant and postpartum women achieve and maintain viral suppression as a matter of urgency.