Fig 1.
Schedule of enrollment, interventions, and assessments for PrEP SMART study.
ENR = enrollment; M1 = Month 1; CASI = computer assisted self-interview; STI = sexually transmitted infection; TFV-DP = tenofovir diphosphate; DBS = dried blood spots. 1Only participants who are “non-responders” to their primary intervention will be randomized at the Month 3 study visit. 2Drug concentration testing will occur at Month 2 for all participants to determine whether they are “non-responders” to the primary intervention; drug concentration testing will occur at Months 3 and 6 only for participants in the drug-level feedback counseling arm. TFV-DP levels will also be assessed among all participants at Month 9 for primary outcome assessment.
Fig 2.
Flow diagram of study enrollment, randomization, and intervention arms.
1A participant is considered a “non-responder” if they have Month 2 TFV-DP levels <500 fmol/punch or missed PrEP refills at the Month 1 and/or Month 2 study visits. Secondary randomization takes place at the Month 3 study visit.
Table 1.
Study inclusion and exclusion criteria.
Fig 3.
Drug-level feedback counseling messages and corresponding TFV-DP thresholds.
“Sample month” refers to the month when the TFV-DP sample was collected. “Results month” refers to the month when the results were given to the participant (e.g., for blood samples drawn at the Month 2 visit, TFV-DP results were reported to participants during their Month 3 visit. For TFV-DP levels greater than or equal to 500 fmol/punch, participants were shown the green wifi signal as a visual representation of their drug levels and they were told the accompanying counseling message by the counselor. For TFV-DP levels between detectable (>16 fmol/punch) and 499 fmol/punch, participants were shown the yellow wifi signal and were told the accompanying counseling message. Finally, for TFV-DP levels below the limit of quantification, participants were shown the red wifi signal and were told the accompanying counseling message.
Table 2.
Adaptive adherence support strategies.