Outcomes after loss to follow-up for pregnant and postpartum women living with HIV and their children in Kenya: A prospective cohort study

Many prevention of vertical transmission (PVT) studies assess outcomes within 12 months postpartum and exclude those lost to follow-up (LTFU), potentially biasing outcomes toward those retained in care. Five public facilities in western Kenya. We recruited women living with HIV (WLH) ≥18 years enrolled in antenatal clinic (ANC). WLH retained in care (RW) were recruited during pregnancy and followed with their children through 6 months postpartum; WLH LTFU (LW, last visit >90 days) after ANC enrollment and ≤6 months postpartum were recruited through community tracing. Re-contact at 3 years was attempted for all participants. Primary outcomes were retention and child HIV-free survival. Generalized linear regression was used to estimated risk ratios (RR) for associations with becoming LTFU by 6 months postpartum, adjusting for age, education, facility, travel time to facility, gravidity, income, and new vs. known HIV positive at ANC enrollment. 333 WLH (222 RW, 111 LW) were recruited from 2018-2019. More LW versus RW were newly diagnosed with HIV at ANC enrollment (49.6% vs. 23.9%) and not virally suppressed at study enrollment (40.9% vs. 7.7%). 6-month HIV-free survival was lower for children of LW (87.9%) versus RW (98.7%). At 3 years, 230 WLH were retained in care (including 51 previously LTFU before 6 months), 30 transferred, 70 LTFU, and 3 deceased. 3-year child HIV-free survival was 81.9% (92.0% for children of RW, 58.6% for LW), 3.7% were living with HIV, 3.7% deceased, and 10.8% had unknown HIV/vital status. Being newly diagnosed with HIV at ANC enrollment was the only factor associated with becoming LTFU (aRR 1.21, 95% CI 1.11-1.31). Outcomes among those LTFU were worse than those retained in care, underscoring the importance of retention in PVT services. Some, but not all, LW re-engaged in care by 3 years, suggesting that PVT services must better address the barriers and transitions women experience during pregnancy and postpartum.