Background:
PrEP is scaling up among pregnant and postpartum women in Kenya, yet few longitudinal data exist on PrEP adherence in this population. We evaluated PrEP adherence measured via tenofovir-diphosphate (TFV-DP) concentrations in dried blood spots (DBS) collected from Kenyan women who initiated PrEP during pregnancy and were followed postpartum.
Methods:
We prospectively analyzed data from a subset of participants in the PrIMA Study (NCT03070600) who enrolled during the 2nd trimester, initiated PrEP during pregnancy, and were followed through 9-months postpartum. At follow-up visits (monthly in pregnancy; 6 weeks, 6 months, 9 months postpartum), self-reported PrEP use was assessed and DBS were collected. Among a random subset of participants, DBS quantifying TFV-DP concentrations were tested from all visits with any self-reported PrEP use in the last 30 days. TFV-DP benchmarks were defined by thresholds from directly observed studies (IMPAACT 2009) among women in the 2nd trimester of pregnancy and postpartum.
Results:
Overall, 198 participants met inclusion criteria for this analysis and were randomly selected (28% of all PrEP initiators in PrIMA); each participant contributed a median of 3 visits to the analysis (IQR 2-4). The median gestational age at PrEP initiation was 27 weeks (IQR 22-30), 91% of participants were married, and 19% had a partner known to be living with HIV. Among visits where participants continued with PrEP (n=454), 94% (427/454) reported any PrEP use in the last 30 days. Among DBS from these visits (n=427), 48% had detectable TFV-DP of which 28% had TFV-DP concentrations indicating < 2 doses/week, 64% 2-6 doses/week, and 8% 7 doses/week. Having a partner known to be living with HIV was associated with a 2-fold higher likelihood of any detectable TFV-DP compared to having partners who were HIV-negative or of unknown HIV status (risk ratio [RR]=2.0, 95%CI:1.6-2.7, p < 0.001). Detectable TFV-DP was also more likely during pregnancy compared to postpartum (RR=1.4, 95%CI:1.1-1.7, p=0.002) and among women aged ≥24 years compared to younger women (RR=1.8, 95%CI:1.3-2.6, p < 0.001).
Conclusions:
Similar to studies of antiretroviral therapy among women living with HIV, we found that PrEP adherence was higher during pregnancy than postpartum, though adherence to 7 doses/week was low overall. Interventions should prioritize sustaining adherence in the postpartum period and increasing knowledge of partner HIV status, especially among younger women.