Background
Non-adherence to oral TDF/FTC PrEP reduces efficacy for HIV prevention, including in pregnant and postpartum women (PPW). Urine tenofovir (TFV) testing detects dosing in past 72 hours in people taking oral PrEP, but there are few insights into whether providing PPW with feedback on urine TFV test results can support PrEP adherence. We examined this as the primary outcome of Step 1 of the Stepped Care to Optimize PrEP Effectiveness in PPW trial (NCT05322629).
Methods
We enrolled pregnant women attending primary care antenatal services in Cape Town without HIV who were >15 years old, >20 weeks’ gestation, and initiating or taking PrEP in pregnancy. We block randomized women 1:1 to the intervention (Int; biofeedback counseling based on urine TFV test result) vs. standard of care control (SOC; PrEP counseling without biofeedback; urine collected and TFV testing performed without the participant). PrEP was delivered to all women through standard public health services. The primary outcome was the impact of the urine TFV biofeedback intervention on objective PrEP adherence measured at 6m (based on urine TFV test results in both arms). Primary analyses were via intention to treat and assumed that women who did not attend the 6m study follow-up visit were non-adherent to PrEP. Results are presented at risk ratios (RR) with 95% Confidence Intervals (CI).
Results
Among 750 HIV- women on or initiating PrEP in pregnancy randomised (375 Int; 375 SOC), median age was 26 years (IQR:22-32); median gestational age was 29 weeks (IQR:23-35); 38% were married or cohabiting. Overall, 54% of women attended the 6m primary outcome visit (Int=58%; SOC=51%) of whom 66% self-reported PrEP in the past week (Int=68%, SOC=64%). For the primary outcome, 32% of Int participants had urine TFV+ (n=120 of 372) vs. 25% in SOC (n=91 of 365) (RR=1.29; 95% CI=1.03-1.63; Table). Findings persisted after adjustment for socio-demographic and HIV risk factors and were consistent across subgroups of PPW age, timing of enrollment and follow-up, and HIV risk markers.
Conclusions
In this setting a large proportion of women initiating PrEP in pregnancy do not persist through 6m; however, biofeedback using urine TFV testing was associated with small but significant increases in PrEP adherence. These findings point to the urgent need for long-acting PrEP modalities for PPW, and among women who use oral TDF/FTC, the potential impact of biofeedback interventions to enhance adherence.